Intelligent Transportation

Systems (ITS) Design Manual

October 2021
 ITS Design Manual

Table of Contents
1. Introduction ........................................................................................................................1-1
1.1. What are Intelligent Transportation Systems (ITS)? .............................................................1-1
1.2. Purpose and Use ............................................................................................................1-1
1.3. Acronyms and Definitions................................................................................................1-1
1.4. References ....................................................................................................................1-7
1.5. Manual Organization ......................................................................................................1-8
1.6. MnDOT Organization ......................................................................................................1-8
1.7. Minnesota Information Technology Services .................................................................... 1-11
1.8. Written Communication Policy ....................................................................................... 1-11
1.9. Disclaimer ................................................................................................................... 1-11
2. Project Development Process.................................................................................................2-1
2.1. ITS Project Types ............................................................................................................2-1
2.2. Project Delivery Methods ................................................................................................2-1
2.3. Systems Engineering Approach.........................................................................................2-2
2.4. Planning and Pre-Design..................................................................................................2-4
2.5. General Design Guidance ................................................................................................2-5
2.6. Typical Design Review Process .........................................................................................2-8
2.7. Bid and Construction Support ........................................................................................ 2-10
2.8. Operations and Maintenance......................................................................................... 2-10
2.9. Project Timelines.......................................................................................................... 2-10
3. Supporting Infrastructure Design ............................................................................................3-1
3.1. Power Distribution .........................................................................................................3-1
3.2. Communications .......................................................................................................... 3-29
3.3. Conduit....................................................................................................................... 3-38
3.4. Conduit Access............................................................................................................. 3-43
3.5. Equipment and Service Cabinets and Shelters................................................................... 3-44
3.6. Additional Supporting Infrastructure............................................................................... 3-48
3.7. ITS Device Design ......................................................................................................... 3-51
4. Plans, Specifications, and Estimate (PS&E) Design Steps .............................................................4-1
4.1. General.........................................................................................................................4-1

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4.2. Typical Plan Sets and Components ....................................................................................4-4

4.3. MnDOT Standard Specifications for Construction .............................................................. 4-22
4.4. Approved/Qualified Products List ................................................................................... 4-25
4.5. Pay Items .................................................................................................................... 4-25
4.6. Tabulation/Statement of Estimated of Quantities ............................................................. 4-26
4.7. General Design Steps .................................................................................................... 4-26
4.8. Detailed Design Steps ................................................................................................... 4-30

List of Figures
Figure 1-1: RTMC Organization Chart ..........................................................................................1-9
Figure 3-1: MnDOT RTMC Utility Coordination Spreadsheet ...........................................................3-6
Figure 3-2: Typical Power Service - Pole-Mounted Transformer ......................................................3-7
Figure 3-3: Typical Power Service - Pole-Mounted Transformer behind Noise Wall ............................3-8
Figure 3-4: Typical Power Service - Ground-Mounted Transformer within MnDOT R.O.W. ..................3-8
Figure 3-5: Typical Power Service - Ground-Mounted Transformer outside MnDOT R.O.W. with Service
Pedestal within MnDOT R.O.W. .................................................................................................3-9
Figure 3-6: Circuit Types Exhibit ............................................................................................... 3-12
Figure 3-7: Voltage Drop Example ............................................................................................ 3-21
Figure 3-8: Point to Point Topology Schematic ........................................................................... 3-31
Figure 3-9: Daisy Chain Topology Schematic............................................................................... 3-31
Figure 3-10: Multi-Drop Topology Schematic ............................................................................. 3-31
Figure 3-11: Ring Topology Schematic....................................................................................... 3-31
Figure 3-12: Star Topology Schematic ....................................................................................... 3-32
Figure 3-13: Multi-Point Topology Schematic ............................................................................. 3-32
Figure 3-14: Cloud Topology Schematic ..................................................................................... 3-32
Figure 3-15: Network Diagram ................................................................................................. 3-34
Figure 3-16: Common Ethernet Equipment................................................................................ 3-37
Figure 3-17: 334Z Cabinet ....................................................................................................... 3-45
Figure 3-18: Pole Cabinet ........................................................................................................ 3-46
Figure 3-19: Service Cabinet .................................................................................................... 3-47
Figure 3-20: Service Cabinet Type Special .................................................................................. 3-47

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Figure 3-21: Service Cabinet 240/480 with Stepdown Transformer................................................ 3-48

Figure 3-21: NID Pole.............................................................................................................. 3-50
Figure 3-22: NID .................................................................................................................... 3-53
Figure 3-23: Detector Folding Pole Placement and Height............................................................ 3-55
Figure 3-24: Loop Detector Configuration on Entry Ramps ........................................................... 3-59
Figure 3-25: Loop Detector Index Number ................................................................................. 3-60
Figure 3-26: Loop Detector Function Designations ...................................................................... 3-60
Figure 3-27: Video Camera ...................................................................................................... 3-62
Figure 3-28: 50’ Video Camera Folding Pole Swing Path ............................................................... 3-65
Figure 3-29: Dynamic Message Sign.......................................................................................... 3-67
Figure 3-30: DMS Visibility (Not to Scale)................................................................................... 3-71
Figure 3-31: Tolling Antenna Overhead Sign Truss Mounting Detail ............................................... 3-76
Figure 3-32: Tolling Antenna Bridge Mounting Detail .................................................................. 3-76
Figure 3-33: Tolling Antenna Pipe Mounting Detail ..................................................................... 3-77
Figure 3-34: Sample E-ZPass Signing Plan (Added Lane) ............................................................... 3-79
Figure 3-35: Sample E-ZPass Signing Plan (Dropped General-Purpose Lane).................................... 3-80
Figure 3-36: Concrete Median Barrier Design Special 1 Detail ....................................................... 3-81
Figure 3-37: Concrete Median Barrier Transition Detail ............................................................... 3-82
Figure 3-38: Ramp Meter ........................................................................................................ 3-84
Figure 4-1: MnDOT Standard Specifications for Construction........................................................ 4-22
Figure 4-2: Spec Book 1504, Coordination of Contract Documents ................................................ 4-23
Figure 4-3: AASHTOWare Website............................................................................................ 4-26

List of Tables
Table 1-1: Acronyms and Definitions...........................................................................................1-2
Table 3-1: Electrical Wire Characteristics ................................................................................... 3-10
Table 3-2: Typical MnDOT ITS Device Power Requirements .......................................................... 3-16
Table 3-3: Maximum Preferred Amperage for 3% Voltage Drop with 120 Volts Unbalanced Load ...... 3-17
Table 3-4: Maximum Preferred Amperage for 3% Voltage Drop with 120/240 Volts Balanced Load.... 3-18
Table 3-5: Power Over Ethernet Parameters .............................................................................. 3-27
Table 3-6: Comparison of Common Communication Topologies.................................................... 3-33

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Table 3-7: Serial Communications Protocol Characteristics........................................................... 3-35

Table 3-8: Example Conduit Fill Calculations .............................................................................. 3-39
Table 3-9: Typical Conduit Dimension for Rigid Steel Conduit (RSC) ............................................... 3-41
Table 3-10: Typical Conduit Dimension for Schedule 80 PVC and Schedule 80 HDPE (NMC)............... 3-41
Table 3-11: Wavetronix Mounting Height .................................................................................. 3-54
Table 3-12: Detector Technology Strengths and Weaknesses ....................................................... 3-55
Table 3-13: FHWA Vehicle Classification .................................................................................... 3-58
Table 3-14: Detection Components .......................................................................................... 3-58
Table 3-15: Video Camera Components..................................................................................... 3-63
Table 3-16: DMS Components.................................................................................................. 3-68
Table 3-17: DMS Support Type Comparison ............................................................................... 3-73
Table 3-18: HOT Lane Components........................................................................................... 3-74
Table 3-19: Ramp Meter Components....................................................................................... 3-85
Table 4-1: General Design Steps ............................................................................................... 4-27
Table 4-2: Vehicle Detection Design Steps ................................................................................. 4-30
Table 4-3: Video Camera Design Steps ...................................................................................... 4-33
Table 4-4: DMS Design Steps ................................................................................................... 4-37
Table 4-5: HOT Lane Design Steps ............................................................................................ 4-41
Table 4-6: Ramp Meter Design Steps ........................................................................................ 4-43

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1. Introduction
1.1. What are Intelligent Transportation Systems (ITS)?
The United States Department of Transportation (USDOT) Federal Highway Administration (FHWA)
defines Intelligent Transportation Systems, or ITS, as the integration of advanced communications
technologies into the transportation infrastructure and within vehicles to improve transportation safety
and mobility and enhance American productivity. ITS encompasses a broad range of wireless and wire
line communications-based information and electronics technologies.
The Minnesota Department of Transportation (MnDOT) further defines ITS as electronics,
communications, or information processing systems or services used to improve the efficiency and
safety of the surface transportation system. MnDOT utilizes ITS to help deliver on the Department’s
overall vision of creating a multimodal transportation system that maximizes the health of people, the
environment, and the state’s economy. MnDOT strives to implement new technologies and systems into
Minnesota’s transportation system to achieve a safer, more accessible, efficient, and reliable
multimodal transportation system that connects people to destinations and markets throughout the
state, regionally, and around the world. Through ITS infrastructure implementation, MnDOT targets a
goal of providing real-time traffic conditions to the public to provide them with tools to make informed
decisions about their planned routes, prior to and during their trips.

1.2. Purpose and Use

The purpose of the MnDOT ITS Design Manual is to provide individuals familiar with ITS an overview of
the MnDOT project development process and information to assist in the design of ITS infrastructure for
MnDOT. While ITS technologies share many similarities with traffic signal and roadway lighting
elements, they are unique and require their own set of design criteria and have many unique qualities
and considerations. This manual is focused on agency and consultant personnel who are engaged in ITS
design and project management with MnDOT.
This manual is intended to be a living document and may be periodically updated. Users should
periodically check the MnDOT website for updates to this manual. A current version of the ITS Design
Manual can be accessed using the link below.
MnDOT ITS Design Manual: http://www.dot.state.mn.us/its/design.html
MnDOT has published other manuals such as signal design, maintenance, etc. The website below houses
links to other MnDOT manuals.
MnDOT Manuals: http://www.dot.state.mn.us/manuals/

1.3. Acronyms and Definitions

The table below includes a list of ITS acronyms and definitions used throughout this document.

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Table 1-1: Acronyms and Definitions

Term Definition
511 Traveler Information System (TIS) The State of Minnesota’s 511 Traveler Information System
(https://hb.511mn.org) provides real-time travel
information including traffic speeds, video camera
snapshots, DMS messages, road weather information, and
traffic alerts.
Absorbed Gas Mat (AGM) A type of battery that is designed for delivering powerful
bursts of starting amps and running electronics for a long
time.
American Association of State Highway A nonprofit, nonpartisan association representing highway
Transportation Officials (AASHTO) and transportation departments in the United States. It
serves all transportation modes and its goal is to foster the
development, operation, and maintenance of the
integrated national transportation system.
Architecture The organizational structure of a system, identifying its
components, their interfaces, and a concept of execution
among them.
Advanced Transportation Management Systems of detection, communication, and software
System (ATMS) technologies that are aimed to reduce traffic congestion.
American Wire Gauge (AWG) US standard used by MnDOT to measure wire conductor
sizes.
Video Camera A camera that transmits video to a monitor screen that is
used to provide traffic monitoring by the facility operator
along the length of the facility and particularly at points of
entry and tolling locations.
Components Components are the named "pieces" of design and/or
actual entities [sub-systems, hardware units, software
units] of the system/sub-system. In system/sub-system
architectures, components consist of sub-systems [or
other variations], hardware units, software units, and
manual operations.
Concept of Operations (ConOps) A foundation document that frames an overall proposed
system and sets the technical course for a project.
Connected Vehicle (CV) A vehicle that uses devices and networks to communicate
with other vehicles and field devices.
Dedicated Short-Range Communication A type of communication used in Connected Vehicle
(DSRC) technology to communicate between vehicles and
roadside devices.
Department of Transportation (DOT) A government agency, federal, statewide, or local,
dedicated maintaining and developing transportation
systems and infrastructure.
Design Those characteristics of a system or components that are
selected by the developer in response to the
requirements.
Detector Loops Consists of one or more turns of insulated loop wire
installed in a shallow slot sawed in the pavement surface

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Term Definition
or installed in the subgrade that are can be used to
determine traffic characteristic such as: count vehicles,
measure traffic speed, and detect the presence of
vehicles.
Django A content management system created in Python that
creates reports from IRIS and other databases. The system
is used by MnDOT designers for a variety of reasons. A few
examples are to review fiber schematics, search for past
projects in an area, and identify MnDOT staff assigned to a
particular project.
Dynamic Message Sign (DMS) An electronic sign deployed on roadways to inform
travelers of specific warnings including but not limited to
congestion, special events, traffic incidents, and other
emergency alerts. Most DMS can display one or more
predefined messages automatically without user
intervention. MnDOT most often uses the term DMS in ITS
design although some use the term Variable Message Sign
(VMS) and Changeable Message Sign (CMS)
interchangeably. Portable Changeable Message Signs are
trailer mounted signs that are used in work zones and as
an incident management tool. Blank-Out Sign (BOS) are a
specific type of DMS that have the capability to show a
blank message or a fixed message(s).
Express Lanes A lane or set of lanes physically separated or barriered
from the general-purpose lane capacity provided within
major roadway corridors. Express lane access is managed
by limiting the number of entrance and exit points to the
facility. Express lanes may be operated as reversible flow
facilities or bi-directional facilities. These can include High-
Occupancy Toll lanes.
Federal Aviation Administration (FAA) A division of the USDOT that is responsible for the
regulation and oversight of civil aviation within the United
States.
Federal Communications Commission An independent agency of the United States government
(FCC) created by statute to regulate interstate communications
by radio, television, wire, satellite, and cable.
Federal Highway Administration (FHWA) A division of the USDOT that specializes in highway
transportation.
Freeway Incident Response Safety Team The FIRST program, formerly known as Highway Helper
(FIRST) program, is tasked with minimizing congestion and
preventing secondary crashes through the quick response
and removal of incidents. The FIRST program is a key
component of the Twin Cities Metropolitan Area Incident
Management Program.
Georilla Georilla is an internal MnDOT web-map application that is
currently being used by approximately 700 unique visitors

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Term Definition
per month to match-up asset, project, and activity
information to make better data-driven decisions. The
Asset Management Project Office Supports the
development and direction of Georilla.
Global Positioning System (GPS) A satellite-based navigation system that provides
geolocation and time information to a GPS receiver.
Hardware Articles made of material, such as tools, computers,
vehicles, fittings, and their components [mechanical,
electrical, electronic, hydraulic, and pneumatic]. Computer
software and technical documentation are excluded.
High Density Polyethylene (HDPE) A thermoplastic polymer used for many applications. In ITS
design it us used for underground conduit systems.
High-Occupancy Toll (HOT) Lane Managed, limited-access, highway lanes that provide free
access to HOVs, and make excess capacity available to
other vehicles not meeting occupancy requirements at a
market price.
High-Occupancy Vehicle (HOV) A passenger vehicle carrying more than a specified
minimum number of passengers, such as an automobile
carrying more than one or more than two people. HOVs
include carpools and vanpools, as well as buses.
HOV Lane An exclusive traffic lane or facility limited to carrying HOVs
and certain other qualified vehicles.
Institute of Electrical and Electronics A professional organization focused on advancing
Engineers (IEEE) technology, comprised of electrical and electronics
engineers.
Incident Management Managing forms of non-recurring congestion, such as
spills, collisions, immobile vehicles, or any other
impediment to smooth, continuous flow of traffic on
freeways.
Infrastructure Fixed facilities, such as roadway or railroad tracks;
permanent structures.
Intelligent Transportation Systems (ITS) A broad range of diverse technologies which, when
applied to our current transportation system, can help
improve safety, reduce congestion, enhance mobility,
minimize environmental impacts, save energy, and
promote economic productivity. ITS technologies are
varied and include information processing,
communications, control, and electronics. Intelligent
Transportation Systems facilitate providing real-time
information on traffic conditions to travelers on roadways
for which the technologies are deployed on.
Interface The functional and physical characteristics required to
exist at a common boundary - in development, a
relationship among two or more entities [such as
software-software, hardware-hardware, hardware-
software, hardware-user, or software-user].

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Term Definition
Internet Protocol (IP) The method by which data is communicated between
devices on the Internet
Intelligent Roadway Information System MnDOT’s Freeway Management System control software.
(IRIS) IRIS is an open-source ATMS software project developed
by MnDOT.
Legacy System The existing system to which the upgrade or change will
be applied.
Life-Cycle Maintenance Concept of keeping a facility or system useable at least
through its design life by conducting scheduled
maintenance.
Light Emitting Diode (LED) A type of light source illuminated by the movement of
electrons.
Manual on Uniform Traffic Control A document published by the Federal Highway
Devices (MUTCD) Administration setting standards and providing guidance
to ensure uniformity of traffic control devices across the
United States.
Minnesota Manual on Uniform Traffic A document published by MnDOT setting standards and
Control Devices (MN MUTCD) providing guidance to ensure uniformity of traffic control
devices across the state of Minnesota.
National Electrical Code (NEC) A standard for the installation of electrical wiring and
equipment that ensures safety, also known as NFPA 70.
National Electrical Manufacturers A trade organization comprised of electrical equipment
Association (NEMA) and medical imaging manufacturers that make safe,
reliable, and efficient products and systems in seven
markets, including transportation systems.
National Electrical Safety Code (NESC) A standard that outlines methods for the safety of electric
supply and public and private communication utility
systems.
National Transportation Communications A group of standards that provides both protocols and
for ITS Protocol (NTCIP) vocabulary necessary to ensure consistency between ITS
device manufacturers.
Non-Intrusive Detector (NID) A vehicle detector that is not installed into the pavement.
MnDOT currently utilizes side-fire, FMCW microwave
vehicle detection to detect vehicles traveling along
freeway mainlines.
Plans, Specifications, and Estimates A package for a project that includes the plans,
(PS&E) specifications, and cost estimate for the project that is
ready to be bid on by contractors.
Polyvinyl Chloride (PVC) A solid plastic that is often used to make pipes, including
to construct underground conduit.
Radio Frequency (RF) The rate of oscillation or range of rates of electromagnetic
radio waves used in telecommunications.
Ramp Metering The electronically regulated flow of vehicles on highway
entrance ramps and loops to reduce crashes, reduce
congestion, and provide more reliable travel times.

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Term Definition
Regional ITS Architecture A specific regional framework for ensuring institutional
agreement and technical integration for the
implementation of ITS projects in a particular region.
Remote Weather Information A system of sensors, communications, and data collection
System/Roadway Weather Information technologies to measure specific weather conditions
system (RWIS) including atmospheric, pavement and/or water level
conditions.
Roadside Unit (RSU) A device on a roadway that communicates with on-board
units in connected vehicles and sends information back to
a traffic management center.
Small Form-Factor Pluggable (SFP) A compact, hot-pluggable network interface module used
for both telecommunication and data communications
applications.
Source of Power (SOP) Electric utility transformer that provides power to a device
or infrastructure.
Specification A document that describes the essential technical
requirements for items, materials or services including the
procedures for determining whether the requirements
have been met.
Single-Occupancy Vehicle (SOV) A passenger vehicle containing only a single occupant.
System An integrated composite of people, products, and
processes, which provide a capability to satisfy a stated
need or objective.
Systems Engineering An interdisciplinary approach and a means to enable the
realization of successful systems. Systems engineering
requires a broad knowledge, a mindset that keeps the big
picture in mind, a facilitator, and a skilled conductor of a
team.
Traffic Management Center (TMC) A location to collect real-time data on the surrounding
transportation system to monitor conditions, manage the
systems in the field, and provide traveler information.
Traffic Management System (TMS) The development and application of network-wide data
collection and sharing of traffic information system. The
system can integrate data and control systems from
freeways, arterials, and city streets to provide real-time
proactive traffic information and control. Implementation
of the system would facilitate congestion management
over the entire network across multijurisdictional
boundaries. The system could provide incident detection,
transit and emergency vehicle priority, and advance
traveler information.
Uninterruptible Power Supply (UPS) A device that is used as emergency power when there's an
interruption to the standard power.
Volts - Alternating Current (VAC) A measure of circuit power pressure for alternating
current.
Volts - Direct Current (VDC) A measure of circuit power pressure for direct current.

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1.4. References
The ITS Design Manual is intended to be used as a resource for MnDOT agency and consultant personnel
performing ITS project management and design services for the department. This manual incorporates
information from multiple MnDOT resources, and individuals managing ITS projects or performing ITS
design services are encouraged to familiarize themselves with these documents and their contents. A list
of key MnDOT resources have been detailed below along with a web link to access the current version of
the document. Please note that reference material is updated often, and users should periodically check
for new or updated versions of these documents.
The MnDOT Office of Traffic Engineering website includes a wide array of traffic engineering and ITS
topics. The website can be accessed using the link below.
MnDOT Office of Traffic Engineering: http://www.dot.state.mn.us/trafficeng/
The MnDOT Regional Traffic Management Center (RTMC) handles coordination between State Patrol
and MnDOT Maintenance and Freeway Operations. The center’s website is an excellent source for
information on the Freeway Incident Response Safety Team (FIRST), as well as other traffic operations
and traveler information. In addition, the RTMC website includes information on traffic operations and
system design. The website can be accessed using the link below.
MnDOT RTMC: http://www.dot.state.mn.us/rtmc/trafficoperations.html
Information on MnDOT’s activities and policies related on Connected and Automated Vehicles (CAV) can
be found on MnDOT’s CAV-X website. This website contains links to the report published by the
Minnesota governor’s advisory council on CAV, as well as information on the state’s CAV challenge.
MnDOT CAV-X: http://www.dot.state.mn.us/automated/
In addition to the MnDOT resources detailed above, several additional resources were used in the
development of the ITS Design Manual and should be referenced for additional information. Additional
ITS resources have been detailed below.
Additional ITS Resources:
• USDOT A Guide for HOT Lane Development
(https://www.ibtta.org/sites/default/files/A%20Guide%20for%20HOT%20Lane%20Developmen
t%20FHWA.pdf)
• FHWA Systems Engineering Guidebook for ITS
(www.fhwa.dot.gov/cadiv/segb/index.htm)
• Enterprise Warrants for the Installation and Use of Technology Devices for Transportation
Operations and Maintenance (http://enterprise.prog.org/itswarrants/)
• FHWA Traffic Detector Handbook: Third Edition—Volume I
(https://www.fhwa.dot.gov/publications/research/operations/its/06108/06108.pdf)
• Wisconsin Department of Transportation – Intelligent Transportation Systems (ITS) Design and
Operations Guide, October 2009
(https://wisconsindot.gov/dtsdManuals/traffic-ops/manuals-and-standards/its/01/01-01.pdf)
• FHWA Office of Operations - Traffic Control Systems Handbook
(http://ops.fhwa.dot.gov/publications/fhwahop06006/index.htm)

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• MnDOT Evaluation of Non-Intrusive Technologies for Traffic Detection

(http://www.dot.state.mn.us/guidestar/2006_2010/nit_phaseIII/FINAL%20REPORT.pdf)
• Pennsylvania Department of Transportation – Publication 646 – Intelligent Transportation
Systems Design Guide, April 2011
(https://www.dot.state.pa.us/public/pubsforms/publications/pub%20646.pdf)

1.5. Manual Organization

The ITS Design Manual includes four chapters and is generally organized as described below.
• Chapter 1: Introduction – Overview of the manual and its contents, list of ITS acronyms and
definitions, MnDOT organizational structure and contact information, and general document
disclaimer
• Chapter 2: Project Development Process – Overview of the MnDOT ITS project development
process
• Chapter 3: Supporting Infrastructure Design – Design guidance for supporting ITS infrastructure
including power service, communications, conduit, conduit access, and cabinets/shelters
• Chapter 4: Plans, Specifications, and Estimate (PS&E) Design Steps – Typical ITS plans,
specifications, engineer’s estimate, and design guidance for common MnDOT ITS elements

1.6. MnDOT Organization

Address and contact information for MnDOT headquarters has been included below along with a link to
the current version of MnDOT’s organizational chart.
Minnesota Department of Transportation
395 John Ireland Blvd.
St. Paul, MN 55155-1800
Phone: (651) 296-3000
Toll-free: (800) 657-3774
MnDOT Organization Chart:
https://www.dot.state.mn.us/information/orgchart/index.html

1.6.1. Regional Transportation Management Center (Metro District)

The RTMC houses MnDOT Freeway Operations personnel, MnDOT Maintenance staff, and Minnesota
State Patrol officers all working together to quickly detect, respond to, and remove incidents from the
transportation system with the goal of improving safety and enhancing mobility across the state. The
RTMC address and contact information has been included below along with a link to the RTMC website.
MnDOT RTMC (Metro District)
Water's Edge Building
1500 West County Road B2
Roseville, MN 55113
Phone: (651) 234-7001
http://www.dot.state.mn.us/rtmc
An organization chart with current primary contacts related to ITS design is included in Figure 1-1.

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Figure 1-1: RTMC Organization Chart

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1.6.2. Shared Services

MnDOT has issued a memo that documents how shared services are used to complete ITS Design. All ITS
projects are to be completed by the RTMC as a shared service due to the specialty nature of the work
and to ensure consistency in ITS systems across the state. Only minimal impact ITS design projects such
as fiber signal interconnect and sole video camera installation may be completed by the District/Office
and those still required review and approval by the RTMC.

1.6.3. Connected and Automated Vehicles Office

The Connected and Automated Vehicles (CAV-X) Office within MnDOT is dedicated to furthering the
state in the field of CAV. A link to MnDOT’s CAV program website as well as information on Minnesota
Executive Order 19-18, the Governor’s CAV Advisory Council, Minnesota’s CAV Challenge, and some of
the benefits associated with CAV technology has been provided below.
MnDOT CAV Website and Contact Information:
http://www.dot.state.mn.us/automated/index.html

1.6.4. Office of Traffic Engineering

MnDOT’s Office of Traffic Engineering (OTE) establishes statewide guidelines and procedures designed
to consistently implement traffic engineering principles across the state. The address for MnDOT OTE
has been included below along with a link to their website and an organizational chart.
MnDOT OTE
1500 W. County Rd B2
Mailstop 725
Roseville, MN 55113
Phone: (651) 234-7000

MnDOT OTE Website:

http://www.dot.state.mn.us/trafficeng/

MnDOT OTE Organization Chart:

http://www.dot.state.mn.us/information/orgchart/co/ote.pdf

1.6.5. Bridges and Structures

MnDOT’s bridges and structures group provides structural guidance and oversight of the state’s bridges
and structures. The address and contact information for MnDOT’s bridges and structures group has
been included below along with a link to the Bridges and Structures website.
MnDOT Bridges and Structures
Mail Stop 610
3485 Hadley Avenue North
Oakdale, MN 55128
Phone: (651) 366-4500

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MnDOT Bridges and Structures Website:

https://www.dot.state.mn.us/bridge/index.html

1.7. Minnesota Information Technology Services

Minnesota Information Technology Services (MNIT) is the central IT organization for the State of
Minnesota and is responsible for establishing IT strategy, direction, policies, and standards for
enterprise IT leadership and planning. MNIT is responsible for the State’s IT infrastructure, applications,
projects, and services. The address and contact information for MNIT has been included below along
with a link to the MNIT website.
MNIT
658 Cedar St
St. Paul, MN 55155
Phone: (651) 201-1118
MNIT Website:
https://mn.gov/mnit/

1.8. Written Communication Policy

To request this document in an alternative format, please contact the Office of Equity and Diversity at
651-366-4720 or 1-800-657-3774 (Greater Minnesota); 711 or 1-800-627-3529 (Minnesota Relay). You
may also send an e-mail to ADArequest.dot@state.mn.us. (Please request at least one week in advance).

1.9. Disclaimer
This manual is disseminated under the sponsorship of the MnDOT CAV-X Office. Standards change
rapidly in the field of ITS so portions of the manual may become out of date between updates. MnDOT
and Kimley-Horn and Associates, Inc. assume no liability for its contents or use thereof. All MnDOT ITS
plans, specifications, and engineer’s construction estimates should be prepared by or under the direct
supervision of a professional engineer licensed to provide engineering services in the State of
Minnesota.
MnDOT does not endorse products or manufacturers. Trademarks of manufacturers’ names appear
herein only because they are considered essential to the object of this manual. The contents do not
necessarily reflect the official policy of MnDOT.

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2. Project Development Process

2.1. ITS Project Types
2.1.1. Stand-alone ITS Projects
Stand-alone ITS projects are led by the RTMC, who is responsible for all management tasks that would
be handled by the roadway group on a roadway construction project. Significant coordination with other
functional groups will be required as a part of design (survey, design, geotechnical, signals & lighting,
structures, signing, etc.). The designer will also need to obtain required input from other groups for
items including the submittal memo, which may require environmental documentation, right-of-way
acquisition, and many other considerations. The designer will need to coordinate reviews with other
functional groups at various milestones throughout the project and is responsible for the final submittal
to Central Office. Since development of the ITS plans are not tied to a larger project, there is more
flexibility in when the milestone submittals need to happen and in the ITS components that are included
in the final design based on project budget considerations.

2.1.2. ITS as Part of Larger Project

For ITS design as part of a larger project, the designer is responsible for the ITS plans and coordination
with other functional groups as needed. All management tasks are handled by the roadway group, who
will need to coordinate with all the other functional groups. The development of the ITS plans will be
more prescribed in following the overall project schedule, where ITS design is typically not started until
after the 30% design.

2.2. Project Delivery Methods

2.2.1. Design-Bid-Build
Design-Bid-Build is the traditional project delivery method in which MnDOT designs, or retains a
designer to furnish complete design services, and then advertises and awards a separate construction
contract based on the designer’s completed construction documents. In Design-Bid-Build, MnDOT
“owns” the details of design during construction and as a result, is responsible for the cost of any errors
or omissions encountered in construction. ITS design is completed as part of the overall plan set and
follows the traditional review process. RTMC staff are more consistently involved throughout the entire
design development of a Design-Bid-Build project. The ITS design on a Design-Bid-Build project may be
completed either by MnDOT or by a consultant.

2.2.2. Design-Build
Design-Build is a project delivery method in which MnDOT procures both design and construction
services in the same contract from a single, legal entity referred to as the design-builder. The method
typically uses Request for Qualifications (RFQ)/Request for Proposals (RFP) procedures rather than the
Design-Bid-Build invitation for bids procedures. The design-builder controls the details of design and is
responsible for the cost of any errors or omissions encountered in construction. On Design-Build
projects, each functional group design is typically developed and approved as a separate design
package. There may be separate design packages for signing, traffic signals, pavement markings,

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maintenance of traffic, ITS, roadway, drainage, and many others. There may also be multiple ITS design
packages that are constructed at different times according to the overall construction staging. MnDOT
RTMC staff are heavily involved early in the project developing the ITS related components of the RFP
for a Design-Build project. Once the Design-Build project is awarded, the ITS design is completed by a
consultant, so MnDOT provides an oversight role on these projects and conducts more Over-The-
Shoulder (OTS) reviews throughout the design process. The development of design packages on Design-
Build projects is accelerated compared to Design-Bid-Build projects, so OTS reviews are utilized more
than traditional 30%/60%/95%/100% submittal reviews.

2.2.3. Construction Manager/General Contractor

Construction Manager/General Contractor (CMGC) is a project delivery method in which MnDOT
contracts separately with a designer and a construction manager. MnDOT can perform the design or
contract with an engineering firm to provide a facility design. MnDOT selects a construction manager to
perform construction management services and construction works. The significant characteristic of this
delivery method is a contract between MnDOT and a construction manager who will be at risk for the
final cost and time of construction. Unlike Design-Bid-Build, Construction Manager/General Contractor
brings the builder into the design process at a stage where definitive input can have a positive impact on
the project. Construction Manager/General Contractor is particularly valuable for new non-standard
types of designs where it is difficult for MnDOT to develop the technical requirements that would be
necessary for Design-Build procurement without industry input. The development of ITS design on a
CMGC project is more similar to Design-Bid-Build, with a difference being that a construction contractor
will complete constructability reviews in order to provide a better final product.

2.3. Systems Engineering Approach

To use federal funds, the project must be compatible with the Regional ITS Architecture and utilize the
appropriate Systems Engineering Checklist(s) that are described below.

2.3.1. Regional ITS Architecture

The Minnesota Statewide Regional Intelligent Transportation Systems (ITS) Architecture Version 2018 is
an update of the previous version that was developed in 2014. The purpose of this update is to: 1) foster
integration of the deployment of regional ITS systems; 2) facilitate stakeholder coordination in ITS
planning, deployment and operations; 3) reflect the current state of ITS planning and deployment; 4)
provide high-level planning for enhancing the state transportation systems using current and future ITS
technologies; and 5) conform with the National ITS Architecture (the Architecture Reference for
Cooperative and Intelligent Transportation, or ARC-IT, Version 8.2) and the Federal Highway
Administration (FHWA) Final Rule 940 and Federal Transit Administration (FTA) Final Policy on ITS
Architecture and Standards.
The Final Rule and the Final Policy provide policies and procedures for implementing Section 5206(e) of
the Transportation Equity Act for the 21st Century (TEA–21), pertaining to conformance with the
National ITS Architecture and Standards. The Final Rule and the Final Policy ensure that ITS projects
carried out using funds from the Highway Trust Fund, including the Mass Transit Account, conform to
the National ITS Architecture and applicable ITS standards.

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Regional ITS architectures help guide the planning, implementation, and integration of ITS components
and systems. ARC-IT is a tool to guide the development of regional ITS architectures. It is a common
framework that guides agencies in establishing ITS interoperability and helps them choose the most
appropriate strategies for processing transportation information, implementing and integrating ITS
components and systems, and improving operations. The Minnesota Statewide Regional ITS
Architecture is a specific application of the framework specified in ARC-IT, tailored to the needs of the
transportation stakeholders in Minnesota.
The Minnesota Statewide Regional ITS Architecture geographically covers the entire state of Minnesota,
encompassing local, regional and state transportation agencies and transportation stakeholders. It
represents a shared vision of how each agency’s systems work together by sharing information and
resources to enhance transportation safety, efficiency, capacity, mobility, reliability, and security. During
the development of the Minnesota Statewide Regional ITS Architecture, agencies that own and operate
transportation systems collaboratively consider current and future needs to ensure that the current
systems, projects and processes are compatible with future ITS projects in Minnesota. The collaboration
and information sharing among transportation stakeholders helps illustrate integration options and gain
consensus on systematic and cost-effective implementation of ITS technologies and systems.
The Minnesota Statewide Regional ITS Architecture is a living document and will evolve as needs,
technology, stakeholders, and funding streams change.
The Minnesota Statewide Regional ITS Architecture, Version 2018 is available at the following link:
http://www.dot.state.mn.us/its/projects/2016-2020/itsarchitecture.html

2.3.2. Systems Engineering Checklist

The Highway Project Development Process (HPDP) includes the following link that provides guidance on
Intelligent Transportation Systems (ITS) and Systems Engineering (SE) Requirements:
http://www.dot.state.mn.us/its/projects/2016-2020/systemsengineering/hpdp.pdf
The purpose of the guidance is to ensure that 23 CFR Section 940 (Rule 940) is implemented on
applicable Trunk Highway projects. FHWA has established Rule 940 based on FTA policy. The intent of
the FTA Policy and Rule 940 is to foster integration of regional ITS systems, which includes the
integration of the deployment of regional ITS systems.
Where applicable, Rule 940 requires that all ITS systems or components be developed based on a
Systems Engineering (SE) process, and that the scale of the SE process be on a scale commensurate with
the project.
• Implementing the ITS SE Process for Rule 940 compliance is required for all ITS projects funded
(in whole or in part) with the highway trust fund (includes National Highway System (NHS) and
non-NHS facilities).
• In addition, MnDOT requires that the ITS SE Process for Rule 940 compliance is followed on all
State Funded ITS projects in which ITS component(s) will be connected/integrated to another
ITS component, project or system.
The ITS SE Process applies to all ITS Class A-1, A-2, B-1, B-2 and C projects that are defined below:

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• Class A-1: Programmatic ITS Applications for Standard Traffic Signals, Road Weather Information
Systems, Weigh-in-Motion Systems, and Railroad-Highway Grade Crossings
• Class A-2: Programmatic ITS Applications for Dynamic Message Signs, Traffic Detection, Video,
Ramp Metering, Communications, Flood Warning Systems, and Slippery, Visibility, and Curve
Warning Systems.
• Class B-1: Freeway Traffic Management
• Class B-2: Arterial Traffic Management
• Class C: Large Scale/Complex ITS Projects
The guidance describes responsibilities and steps that must be followed by the project manager and
district traffic engineer including checklists and SE process that must be followed for various project
types and submittal process.

2.4. Planning and Pre-Design

2.4.1. Concept of Operations
The Concept of Operations:
• Documents the total environment and use of the system to be developed in a non-technical and
easy to understand manner
• Presents this information from multiple viewpoints
• Provides a bridge from the problem space and stakeholder needs to the system level
requirements

2.4.2. Systems Requirements

System requirements are the foundation for building Intelligent Transportation Systems. They
determine what the system must do and drive the system development. System requirements are used
to determine if the project team built the system correctly. The system requirements development
process identifies the activities needed to produce a set of complete and verifiable requirements.

2.4.3. Planning Guidance and Warrants

ITS warrants were developed by the ENTERPRISE pooled fund study. Details can be found at the
following link:
http://enterprise.prog.org/itswarrants/

2.4.4. Statewide ITS Plan Location Criteria

Last published in 2015, MnDOT produces a Statewide ITS Plan which focuses on planning, funding, policy
issues, investment scenarios, future possibilities, and next steps. Within the plan are location criteria for
ITS devices, including video cameras and sensors. The criteria are dependent on the purpose of the
device, the spacing requirements, and the system requirements. The current version of the MnDOT
Statewide ITS Plan is available here:
https://www.dot.state.mn.us/its/projects/2006-2010/mnitsarchitecture/statewideitsplan.pdf

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2.4.5. Pre-Design ITS Device Placement

Once it has been determined which location criteria from the Statewide ITS Plan are met (see Section
2.4.4), the designer will start laying out preliminary locations for the proposed ITS devices. Included
below are important components for developing the pre-design ITS device locations.
AERIALS
At the initial planning stage for determining placement of proposed ITS devices, the designer should
review aerial imagery to identify possible conflict areas and desired placement locations. These factors
may include sight lines, bridges, and other geographical characteristics.
PRELIMINARY LAYOUT
The designer should create a roll plot with an aerial background and inplace utilities and ITS
infrastructure to start pencil-sketching proposed ITS device locations, possible fiber optic trunk line
routing, possible source of power locations, and any other required elements.
FIELD VISIT
After completing the initial draft of the preliminary layout, the designer should perform a field visit to
collect photos and review proposed ITS device locations. For example, a proposed cabinet may be
shown on a steep slope while there is a flatter area nearby that would work better.

2.5. General Design Guidance

2.5.1. Clear Zone Requirements
The AASHTO Roadside Design Guide defines clear zone as the "total roadside border area, starting at the
edge of the traveled way, available for safe use by errant vehicles. This area may consist of a shoulder, a
recoverable slope, a non-recoverable slope, and/or a clear run-out area." The MnDOT Road Design
Manual states that “The roadside clear zone is the distance from the edge of the travel lane which
should be free of any non-traversable hazard such as steep slopes or fixed objects. The clear zone
distances are targeted towards allowing approximately 80 to 85 percent of all run-off-the-road vehicles
to recover or come to a safe stop.”
The width of a clear zone along the horizontal alignment is dependent on roadside geometry, design
speed, radius of any horizontal curve, and the ADT. As an example, a roadway tangent section with 3000
vehicles per day, a posted speed limit of 55 mph and a 1:4 (V:H) fill section would have a calculated clear
zone of 36 feet, per Table 4-6.04A; MnDOT Road Design Manual.
The MnDOT Road Design Manual states that “The designer should not apply rigid adherence to the
calculated clear zone distance. The designer should not use the clear zone distances as boundaries for
introducing roadside hazards such as bridge piers, non-breakaway sign supports, or trees. These should
be placed as far from the roadway as practical.” ITS devices should be placed outside the clear zone
whenever possible, and in cases that it is not possible or feasible the ITS devices must be placed behind
guardrail.

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MnDOT State Aid requirements may differ from those described above, so if the designer is working on
a State Aid Project they need to review the MnDOT State Aid documentation on clear zone best
practices, available at the link below.
https://www.dot.state.mn.us/stateaid/clear-zone.html

2.5.2. Survey and Boring Request

Whenever survey and soil borings are required, the designer will need to submit formal requests to the
appropriate groups. Soil borings are required for every footing for a proposed overhead sign structure,
and the materials group will complete those requests and provide a report that recommends whether a
special foundation be used or if the standard design is adequate. Additional geotechnical review is also
required in areas where shallow bedrock is anticipated as a part of I-Beam sign design because special
post footings may be required, or the sign location may be moved to avoid the bedrock. Additional
geotechnical review may include a review of historic soil borings in the area, ground penetrating radar,
or additional soil borings. Resources for soil borings in the Metro District are available at the link below.
For all Greater Minnesota districts, the designer should coordinate with that district to determine their
process for requesting soil borings.
http://www.dot.state.mn.us/metro/materials/soils.html
If current surveys are not available, they need to be completed in order for the designer to create cross
sections for overhead and roadside ITS devices and design guardrail and grading for those ITS devices.
The designer will need to coordinate with the district survey group to obtain survey information for the
required locations.

2.5.3. MnDOT Utility Coordination Process

The MnDOT utility coordination process is designed to help reduce the time that designers spend on
utility coordination. By identifying early milestones for utility coordination meetings and follow up,
project managers and designers can avoid time-consuming efforts to resolve utility issues that often
occur later in the process. Many MnDOT staff members contribute to successful utility accommodation
and coordination, and each of them plays an important role. The Utility Accommodation and
Coordination Manual details the roles and responsibilities of MnDOT staff members who are involved
with utility coordination for each step of the utility coordination process. The process encourages early
and ongoing communication with utility owners. MnDOT often collaborates with consulting engineers
on the design of highway transportation projects. As a result, consulting engineers are involved with
many aspects of utility coordination, including project management. Resources for the utility
coordination process are available at the following link:
https://www.dot.state.mn.us/utility/projectdelivery.html
On ITS projects, the full utility coordination process is not typically followed. Most inplace public or
private utilities will not be impacted, and under that scenario the utility listings in the plan set will note
all inplace utilities as “LEAVE AS IS”. The designer will need to submit a design locate through Gopher
State One Call to obtain a list of all utility owners in the project area. If source of power modifications or
new sources of power will be required as part of the ITS design, the designer and the MnDOT RTMC
service coordinator will need to coordinate with the power company designer to determine the final
design.

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2.5.4. Environmental Process

All MnDOT projects are required to complete an Early Notification Memo (ENM). The ENM is used to
provide notification of a project and/or request information that may affect project scoping, layout, or
design. Instructions and links to ENM forms are available on the Highway Project Development Process
(HPDP) website at the following link:
http://www.dot.state.mn.us/planning/hpdp/index.html
As part of the ENM, MnDOT’s Environmental Document Decision Tree must be reviewed to determine
what type of environmental documentation is needed for the project under both state and federal rules.

2.5.5. Functionality
The proposed ITS device(s) should be designed to adequately address the existing problems that have
been identified to be addressed. For example, if a series of video cameras are proposed to be added the
designer needs to ensure that the proposed camera locations do not include or minimize blind spots
(assuming they cannot be avoided), or for a proposed DMS the designer needs to ensure that the DMS is
located optimally to facilitate major traffic diversions due to a crash downstream of the DMS.

2.5.6. Constructability
The designer needs to consider the constructability of ITS devices when determining proposed ITS
device locations. For example, all ITS infrastructure and construction equipment should have a minimum
clearance to overhead power lines per Rural Utility Service standards. The designer needs to consider
common construction methods that contractors use to construct the ITS devices that have been
designed and make sure that the design is realistic and practical.

2.5.7. Maintainability
The designer also needs to consider the maintainability of ITS devices when determining proposed ITS
device locations. The two most important considerations are access and safety, and if possible, the
designer should use standard MnDOT approved components so there is consistency in ITS devices
throughout the entire system. The designer needs to consider whether an ITS device will need to be
accessed via a ladder or a bucket truck, whether a lane closure is needed, if there is adequate shoulder
to pull off to access the site, and any other site-specific characteristics that may affect access or safety.
Another consideration regarding ITS device locations is the ease and complexity of underground utility
locating.

2.5.8. Device Collocation

If multiple different ITS devices (video camera, DMS, NID, etc.) are proposed for a certain area, the
designer should evaluate whether it would make sense to place them at the same site. This could reduce
the number if SOP locations, the number of control cabinets, and the number of folding poles. This could
also simplify maintenance operations such as mowing.

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2.6. Typical Design Review Process

The TMS sample plan is located at the link below and provides general information about the design of
TMS plans.
http://www.dot.state.mn.us/metro/finaldesign/pdf/sampleplan/tms.pdf

2.6.1. Conceptual Design (30% Design)

TMS plans are not typically included as part of a larger roadway project plan set for the 30% submittal
and are more of a high-level layout that determines which devices are required and where they are
located. No conduit runs, pull vaults, or sources of power are designed at this point. The RTMC will
review the conceptual ITS design to ensure that all required devices are included as needed.

2.6.2. Detailed Design (60% Design)

Detailed design typically includes all TMS plans except fiber schematics and DMS cross sections, and the
TMS construction plans should be fully annotated. At 60%, the RTMC will review the plans but no other
functional groups will be involved in the project yet.

2.6.3. Integrator Review & Input

After the 60% review and the 60% RTMC design comments have been addressed, the TMS plans should
be provided to an RTMC integrator for their review and input. An integrator will provide input based on
their field experience, and the designer will incorporate comments from the integrator.

2.6.4. Final Design (95% Design)

The 95% submittal will include the Plans, Special Provisions, and Estimate (PS&E) and will be reviewed
by other functional groups as required. Depending on the scope of the TMS construction plans, the PS&E
should be provided to MnDOT Construction, Traffic, Structures, Safety, Drainage, Utilities, and others as
necessary. The MnDOT traffic and/or construction group will complete the Time & Traffic Special
Provisions. This submittal should be distributed to the other groups a minimum of six weeks prior to
plan turn-in. This allows for the four weeks other groups often required to review and provide
comments and two weeks for changes to be incorporated prior to turn-in. The 95% design must be
treated as if it is being issued for construction, there should not be any significant changes between 95%
and 100% design.

2.6.5. Issued for Construction (100% Design)

The 100% PS&E submittal will go to the RTMC and MnDOT Central Office for final approval, and the
vellum title sheet will be routed for signatures. Any comments from the Central Office must be
incorporated prior to bidding. If other changes are made in addition to or that differ from the Central
Office comments, the revised sheets must be resubmitted along with a copy of the same sheets that
highlights those differences.
The RTMC has a state-wide Public Information Finding (PIF) that addresses State-provided materials on
ITS projects. A memo, signed by Central Office, that refers to this PIF and references the applicable

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sections of the PIF based on the particular State-provided materials that will be utilized on the project is
required prior to of plan turn-in.

2.6.6. Additional Input & Reviews

If there are structures as part of the project or if there are any right-of-way concerns, additional input &
reviews may be required by the relevant functional groups. As soon as the designer has determined that
there are components that will require involvement from other functional groups, the designer should
coordinate with the relevant functional groups early in the design process, so they have adequate time
to provide design input. There is more information on this in Chapter 3 and Chapter 4.
TRAFFIC
If signing or pavement markings are required as part of the project, the traffic group should review the
plans at the 95% and 100% submittals. In Metro District, for every project the traffic group also provides
input on the traffic portion of Time & Traffic within Division S. For all other districts this may vary.
Special Provisions are discussed in Section 4.3.
CONSTRUCTION
The construction group should review the plans at the 95% and 100% submittals for all projects. In
Metro District, for every project, the construction group is also responsible for writing the Time & Traffic
portion of Division S with input from the traffic group. For all other districts this may vary. Special
Provisions are discussed in Section 4.3.
SURVEY
If right-of-way information is not available and needs to be obtained, or if there are any other concerns
that may require surveying, the survey group will need to review the plans. The survey group should
review the plans earlier in their development, preferably at the 95% submittal.
FOUNDATIONS
If soil borings are required for overhead sign structures and the geotechnical report recommends that a
special foundation design is required, the foundation group will need to review the plans. This review
should occur with the 95% submittal.
STRUCTURES
If there are any new bridge-mounted structures, such as a DMS installation, the structures group should
review the plans at the 60%, 95%, and 100% submittals.
METAL FABRICATIONS
If there is any proposed structural steel work on any existing or proposed structures, the metal
fabrications group should review the plans at the 60%, 95%, and 100% submittals.

2.6.7. Coordination with Other Disciplines

When the ITS design is being done as part of a larger project, the designer will need to coordinate with
other disciplines including drainage and utilities. This coordination needs to occur so the proposed ITS
design does not conflict with wetland areas, proposed ponds, drainage structures, and other utilities.

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The designer needs to ensure that early in the design process all disciplines are aware of each other’s
proposed design and that regular coordination happens throughout. Any groups that need to be
coordinated with should also participate in the review process described above.

2.6.8. Coordination with Other Projects

The designer must be aware of other projects that are being designed by others that may affect their
own project, so any items that may require coordination during design or construction are addressed
and incorporated into the plans and Special Provisions. For example, plan notes may specify that certain
components shown on the plan are installed under a different SP number. In the Division S Special
Provisions, Section 1505 COOPERATION BY CONTRACTORS should list all projects that the contractor
needs to be aware of and coordinate with. In some cases, it may make sense for separate projects to be
tied and bid on as one package for one contractor to construct both projects, such as if there is an
overhead signing project that will affect some of the same inplace overhead sign structures that the ITS
project is impacting.

2.7. Bid and Construction Support

2.7.1. As-Built Plans
Information about the GPS As-Built Deliverable is available at the link below that describes all
requirements for each asset class. The TMS tab provides information on all the features that need to be
documented for TMS plans.
http://www.dot.state.mn.us/gisspec/index.html
Section 2011 AS BUILTS in Division S describes the requirements for as-built plans, the contractor is
required to provide GPS as-built information for TMS. TMS as-builts typically require Method (2) and
mark-up drawings. Method (2) requires that all coordinates be sub-meter accurate x and y, where
Method (1) requires that all coordinates be sub-foot accurate x, y, and one-tenth-foot accurate z. Mark-
up drawings require that the contractor submits an “As-Built” plan set that includes mark-ups showing
additions, deletions, and other changes made during construction.”
RTMC design staff take the GPS as-built data and mark-up drawings and perform all CAD updates in
MicroStation. All updated CAD linework is viewable in Georilla and the master file is regularly exported
to MicroStation to be used as existing conditions on new ITS projects. Django tracks when as-built data
is received by the contractor, uploaded into Georilla, and other relevant information.

2.8. Operations and Maintenance

It is important that the ITS design addresses the needs of operations and that the ITS system is
ultimately able to be maintained in a safe and efficient manner.

2.9. Project Timelines

There are multiple timelines that need to be considered throughout all projects, including letting
schedules, construction timeframes, and lead times for materials such as steel or fiber optic cable. When
a project is initially setup in the project scheduling software, a customized turn-in date is assigned. There
are minimum time periods that are required to provide for project letting, so if the project turn-in falls

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behind schedule it could have significant impacts on the project letting and award dates, procurement
of materials, and when construction of the project occurs. Additional information about the bid letting
process is available at: https://www.dot.state.mn.us/bidlet/.

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3. Supporting Infrastructure Design

3.1. Power Distribution
3.1.1. Overview
The purpose of this section is to familiarize the designer with the National Electric Code (NEC), the
National Electric Safety Code (NESC), and current MnDOT standards and design guidelines for power
distribution systems associated with ITS infrastructure. Electric services must be located within MnDOT
right-of-way.
The four basic physical characteristics of electricity, noted below, are voltage, current, resistance, and
power. Voltage is the difference in electrical potential between two points of an electrical circuit,
expressed in volts. Voltage measures the potential energy of an electric field to cause an electric current
in an electrical conductor. Current is the rate of flow of electricity through an electrical conductor and is
measured in amperes, or amps. Resistance, measured in ohms, is the resistance of an electrical
conductor to the flow of electricity. Power is the rate at which work is done or energy is transferred.
Work can be measured using many different units but is most often measured in watts when used in
calculations for ITS infrastructure.
Electrical current can be characterized as alternating current (AC) or direct current (DC). Power supplied
by an electric company is typically AC while power provided by a battery is DC. Power can be converted
from AC to DC using a rectifier and from DC to AC using an inverter. A majority of the ITS cabinets, and
subsequently ITS devices, used by the State are supplied by an AC power source. A smaller number of
State ITS cabinets and ITS devices are supplied by low voltage DC power sources that may include
batteries and a solar array.

3.1.2. Compliance with Electric Codes and Standards

The design of all MnDOT electrical systems, including all power infrastructure for ITS elements, should
adhere to the standards and requirements included in the current version of the NEC and the NESC. The
NEC is typically updated every three years, and the NESC is updated every five years. Prior to beginning
any MnDOT ITS design project, the designer should verify they are using the latest versions of the NEC
and NESC. A variance committee has been established to review special cases where it is not practical to
meet all of the requirements in the NEC and the NESC. The designer should notify the MnDOT project
manager and RTMC of all variances to the NEC and NESC, which must be reviewed and approved by the
committee.
The NEC and NESC include standards for:
• Conductor properties
• Conductor insulation
• Maximum recommended voltage drops
• Maximum conduit fill
• Junction box sizing
For additional information refer to the links below:

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• NEC: https://www.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-
standards/detail?code=70
• NESC: https://standards.ieee.org/products-services/nesc/index.html

3.1.3. Electric Service Providers

Power for ITS infrastructure across the state is provided by many electric service providers, and the
electric service provider for each ITS device location will depend on the electric service provider that
covers the specific area in which that device is located. The link below includes an interactive map of
electric service utility providers within the state of Minnesota.
Minnesota Electric Utility Service Provider Map:
http://minnesota.maps.arcgis.com/apps/webappviewer/index.html?id=95ae13000e0b4d53a793423df1
176514/
In some instances, new ITS devices may be located near or adjacent to the dividing line between two
electric service provider service areas. There are several factors that may impact which of the two
electric service providers is preferred, including service provider reliability, rates, policies, service levels,
and existing service agreements with MnDOT. When multiple service providers are available, the
designer should contact the MnDOT project manager to determine the preferred electric service
provider. In addition to the service provider, the designer should consider a number of different factors
when selecting which of multiple available power sources to utilize including the location of the existing
power source, the difficulty in connecting to each power source, the voltage available from the power
source, the difficulty and timeline for obtaining service from the electrical service provider.

3.1.4. Distribution versus Transmission

Electric service providers deliver electricity to consumers in two separate phases: transmission and
distribution. The transmission phase includes the bulk movement of electrical energy from the power
generation facility to a power substation. Electrical transmission lines typically carry three-phase
alternating current at very high voltages (greater than or equal to 69 kilovolts (KV)). The distribution
phase includes delivery of that electrical energy from the power substation to individual consumers at
lower voltages (less than or equal to 34.5KV). Power for all MnDOT ITS devices is obtained from electric
services that are installed off an overhead or underground electric distribution line.

3.1.5. Power Supply

The designer may consider several different options to provide power to an ITS device. The following
power source options can be utilized:
• Existing Electric Service: When available and evaluated for condition (rust, enclosure’s structural
integrity, space for additional circuit breakers), the designer may obtain power from an existing
MnDOT ITS electric service. All MnDOT Districts, except for Metro District, allow sharing service
meters between functional groups (lighting, signals, ITS), but the designer should still check with
each District on a by-project basis. The designer will be required to verify that the existing
service has sufficient capacity to provide power to the new ITS infrastructure without negatively
impacting the power being supplied to any of the existing infrastructure currently supplied by
the service. The engineer should consider the distance between the proposed ITS infrastructure

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and the existing service to determine if use of the existing service will be more cost effective and
maintainable than the installation of a new electric service located closer to the proposed ITS
infrastructure. Every attempt to obtain power from the electric service provider should occur
during the design process; the use of a MnDOT-owned step-down transformer is not preferred
but may be required in some situations. Power runs over 1000 feet are discouraged and require
prior MnDOT approval.
• New Electric Service: If an existing MnDOT ITS power service is not available, power can be
obtained from a new electric service. The service transformer should be located as close to the
ITS device as possible to minimize the length and size of the electric conductors.
• Alternative Power Source: When power service is unavailable in the immediate vicinity of the
proposed ITS infrastructure and installing a long electric cable run is not feasible, the designer
may consider alternate power sources including solar and, in some cases, wind. Use of an
alternate power source will require installation of batteries to store electricity for use when the
solar or wind equipment is unable to provide sufficient power. The use of an alternate power
sources is strongly discouraged.

3.1.6. Obtaining Power Service

Power for ITS infrastructure is obtained by the power coordinator while coordinating with the RTMC
service coordinator. A standard format spreadsheet is used by the RTMC to document all utility
coordination items, including what the power company is responsible for and what the contractor is
responsible for. See Figure 3-1 for a screenshot of the spreadsheet. A copy of the spreadsheet can be
requested from the RTMC. Once the spreadsheet has been completed for the project, it must be
provided to the MnDOT RTMC service coordinator.
MNDOT TMS ELECTRIC SERVICE COORDINATION PROCESS
The individuals involved in the coordination process and their roles are as follows:
• Power Coordinator – MnDOT, County, City, or consultant designer/engineer completing the TMS
design
• RTMC Service Coordinator – MnDOT RTMC design staff responsible for power
coordination/tracking/records
• RTMC Design Supervisor – MnDOT RTMC design staff or project manager
• RTMC Integration – MnDOT RTMC field personnel
• Power Company Designer – designer/field representative for power company
The MnDOT TMS Electric Service Coordination Process is as follows:
1. Project power coordination is initiated at approximately the 60% plan development milestone.
2. Power Coordinator creates the MnDOT RTMC Utility Coordination Spreadsheet and starts
populating information as it is determined.
3. Power Coordinator determines the electric service provider and follows the service provider’s
standard process for obtaining the Power Company Designer’s information and initiating the
service coordination process with the service provider. Contact the Power Company Designer
and provide them a copy of the 60% plan sheet(s) and fill out any necessary load sheets or other
forms that the service provider requires.

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4. Power Coordinator coordinates a field meet with the Power Company Designer and the RTMC
Service Coordinator and discuss the following:
a. Discuss the project turn-in date, letting date, and start date with the Power Company
Designer. Discuss milestones for when Power Company Designer needs to provide
information (plan for 1-2 months for Power Company Designer to determine and
provide costs, easements, and design information)
b. Discuss the availability of 120/240V electric service. The MnDOT RTMC requires
120/240V power from the service point (pad mounted transformer or service pedestal)
c. Determine proposed usage based on main circuit breaker size (30 Amps, 60 Amps, 100
Amps, etc.)
d. Determine access requirements to meter (gate in fence may be needed for power
company access)
e. Discuss that MnDOT will provide a foundation and metered service cabinet for the
service connection point.
f. Discuss that no stepdown transformers are allowed, unless approved by the RTMC
Service Coordinator and RTMC Design Supervisor.
g. Discuss that MnDOT no longer installs a riser on power company poles. The power
company will install a U-channel on the pole to a service pedestal or pad mounted
transformer within MnDOT right-of-way. The service pedestal must have a red marking
stake installed next to it to ensure its visibility when in long grass or deep snow. MnDOT
infrastructure cannot go outside of MnDOT right-of-way to get to the service point.
h. In situations where an electric service isn’t reasonably close and the power company will
not work within MnDOT right-of-way, the MnDOT contractor will provide a 3” non-
metallic conduit with a pull tape within MnDOT right-of-way for the power company to
pull their power cables through. For longer conduit runs, pull vaults will be installed at
500 foot intervals. This infrastructure then becomes the property of the power company
and is their responsibility to locate.
i. In situations where there is a noise wall between the transformer and the meter, the
designer will need to install an access door into the noise wall so the power company
can access the meter.
i. If an access door cannot be installed in the noise wall, there is adequate space
between the noise wall and MnDOT right-of-way, and there is reasonable access
from outside MnDOT right-of-way, the designer will need to install the metered
service cabinet between the noise wall and MnDOT right-of-way and a service
cabinet type special on the highway side of the noise wall.
5. Power Coordinator obtains meter address, account number, and premise number from the
Power Company Designer.
6. Power Coordinator updates RTMC Utility Coordination Spreadsheet with all information
determined up to this point and provides a copy of it to the RTMC Service Coordinator, RTMC
Design Supervisor, RTMC Integration, Power Company Designer, etc.
7. Designer determines all TMS equipment loads to calculate voltage drop and determine
appropriate conductor sizes.
8. Power Coordinator updates RTMC Utility Coordination Spreadsheet with costs provided by
Power Company Designer.

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9. Power Coordinator provides 100% plans and RTMC Utility Coordination Spreadsheet to Power
Company Designer for final written approval. At this point, all information in the spreadsheet
should be filled out except which contractor was awarded the electrical work.
10. Power Company Designer provides a service contract with costs and scope of work that will be
signed by the RTMC Service Coordinator.
11. After the project has been let and awarded, MnDOT’s construction contractor will need to
contact the power company and provide the project start date so the power company can get
their portion of the work scheduled and coordinated. The construction contractor must pay the
power company in order to get the project onto the power company’s construction schedule.
12. Any electric service work performed by the power company on MnDOT right-of-way will need a
permit. The power company is responsible for acquiring such permit from MnDOT.
13. Send all permits for RTMC service work to the RTMC Service Coordinator for review.
14. The service address, account number, and premise numbers have already been determined and
are included in the Division SZ special provisions for the project. The construction contractor
does not need to submit new applications for service. See the Electrical Service section of
Division SZ for more information.

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Figure 3-1: MnDOT RTMC Utility Coordination Spreadsheet

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3.1.7. Placement of ITS Elements

In addition to the device-specific location criteria identified for each ITS device, the designer also needs
to consider all available options to obtain electric service. When possible, the ITS device should be
located as close to source of power as possible to minimize the length and size of power cables required
to supply that device with power. Power cable runs from the metered service cabinet to the ITS device
that are longer than 400 feet must include a service cabinet type special at the ITS device. Power cable
runs that are shorter than 400 feet but do not have a clear line of sight to the ITS device or safe walking
access should also include a service cabinet type special at the ITS device. If more than one potential
option exists to obtain electric service, the designer should consider the voltage available at each
location as a part of the design process.
The following four figures detail typical service cabinet placement under various power service
installation scenarios.
Figure 3-2: Typical Power Service - Pole-Mounted Transformer

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Figure 3-3: Typical Power Service - Pole-Mounted Transformer behind Noise Wall

Figure 3-4: Typical Power Service - Ground-Mounted Transformer within MnDOT R.O.W.

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Figure 3-5: Typical Power Service - Ground-Mounted Transformer outside MnDOT R.O.W. with Service
Pedestal within MnDOT R.O.W.

Most power companies no longer allow MnDOT equipment on their power poles and many are using
service pedestals. It is important to note that most power companies prefer the meter to be less than 15
feet from the service pedestal or pad mounted transformer.

3.1.8. Design Considerations

There are several principles that need to be understood when determining conductor size and the
required circuit breakers for the circuits included in an ITS design. Below is a description of several
electrical principles followed by an example problem.
WIRE GAUGE
American wire gauge (AWG) is a standardized wire gauge system used in the United States and other
countries, especially for nonferrous, electrically conducting wire. Increasing gauge numbers give
decreasing wire diameters, which is similar to many other non‐metric gauging systems. This seemingly‐
counterintuitive numbering is derived from the fact that the gauge number is related to the number of
drawing operations that must be used to produce a given gauge of wire; very fine 30-gauge wire
requires far more passes through the drawing dies than does a 0-gauge wire. Note that for gauges 5
through about 14, the wire gauge is effectively the number of bare solid wires that, when placed side by
side, span 1 inch. That is, 8-gauge wire is about 1/8 inch in diameter. An AWG of 14 is the minimum size
used by MnDOT for ITS applications.
The following minimum conductor sizes need to be incorporated into the design:
• Service conductor from service pedestal to metered service cabinet: #6 or larger
• Feeder circuit serving standard service cabinet type special: #6 or larger
• Branch circuit serving NID or camera pole cabinet: #14 or larger for circuits less than 400' and #8
or larger for circuits over 400'
• Branch circuit serving 334 series cabinet: #8 or larger
• Branch circuit serving 334 series cabinet that shares the same foundation with the service
cabinet: #10 conductors or larger
• Branch circuit serving 18’ wide Ledstar DMS: #8 or larger
• Branch circuit serving 30’ wide Ledstar DMS: #6 or larger
• Branch circuit serving 40’ wide Ledstar DMS: #2 or larger

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• Branch circuit serving shelter: #2 or larger

The designer must also verify that the breakers specified can accommodate the wire sizes specified.
AMPACITY
Ampacity is defined as the maximum amount of electric current a conductor or device can carry before
sustaining immediate or progressive deterioration. The circuit breaker must not be rated for a larger
current than the ampacity of the conductors used in the circuit. Ampacities are listed in Table 3-1.
Table 3-1: Electrical Wire Characteristics
Wire Size (AWG) Ampacity (Amps) Resistance of
Copper Copper Wire
(Ohm / 1000 Ft)
14 15 2.57
12 20 1.62
10 30 1.02
8 45 0.64
6 65 0.41
4 85 0.26
3 100 0.21
2 115 0.16
1 130 0.13
0 150 0.10
00 175 0.08
000 200 0.06
CIRCUIT TYPES
Below is the definition for service conductors and the two types of circuits:
• Service point – The transformer, or service pedestal (if present)
• Service lateral – The power company supplied conductors from the transformer to the service
pedestal (if present)
• Service conductors - The contractor supplied conductors from the service point to the metered
service cabinet.
• Feeder circuit – All circuit conductors between the service equipment, the source of a separately
derived system, or other power supply source and the final branch-circuit overcurrent device.
• Branch circuit – The circuit conductors between the final overcurrent device protecting the
circuit and the outlet(s).
The power company is responsible for conductors on the power company side of the service point.
MnDOT is responsible for service conductors between the service point and the metered service
cabinet. The power company may provide conductors all the way to the service cabinet meter. In that
case, the service cabinet is the service point and there are no service conductors. It is important that the
utility coordination spreadsheet (see Figure 3-1) is completed because not all power companies provide
power in the same fashion.

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• Some power companies provide service conductors to a service pedestal and the service
pedestal becomes the point of service. Under this scenario MnDOT is responsible to install the
conductors between the service pedestal and service cabinet.
• Other power companies provide service conductors to the service side of the service cabinet. In
this case the point of service is the service cabinet meter.

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Figure 3-6: Circuit Types Exhibit

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In terms of TMS design: The service conductors are the circuits from the service cabinet to the
connection with the power company (service point). The branch circuit(s) are the circuits from a service
cabinet or service cabinet type special to the various ITS devices. The feeder circuit is circuit between
the service cabinet and service cabinet type special. Service conductors are located on the service side
of the service pedestal. Figure 3-6 shows the circuit types.
CURRENT REQUIREMENTS
The total current required for an ITS application for a branch or feeder circuit is the sum of the
following:
• Current requirements for all ITS device(s) (e.g., shelter, DMS, video camera, vehicle detection,
controller cabinet, etc.) on each leg of every branch or feeder circuit
Power cables and the circuit breakers should be sized based on the total current required for all ITS
devices and cabinet components being served. The current required for various ITS devices can be found
in Table 3-2. When determining the total current required, do not factor-in both devices when those
devices perform opposing functions and are not expected to operate simultaneously (e.g., heater and
air-conditioner). The current value used for sizing the conductors and circuit breakers considers
continuous loads and non-continuous loads (see the section on Breaker Sizing). The conductors must
have sufficient ampacity to carry the current rating of the circuit breaker, unless the conductor ampacity
is not a standard circuit breaker size, then the circuit breaker can be the next biggest standard size. The
distinction of continuous and non-continuous loads only applies for determining minimum wire and
circuit breaker sizes and is not considered for calculating voltage drops.
Note that a larger conductor size may be required in order to keep the voltage drop over longer lengths
below the recommended maximums. Current load requirements for individual ITS devices should be
obtained from the Table 3-2 and, if not identified or the devices are from a different
vendor/manufacturer, from the manufacturer/vendor of that specific ITS device.
VOLTAGE DROP
In order to properly size the electrical conductors in a feeder circuit that will supply power to a service
cabinet type special, and subsequently each ITS device connected to the cabinet via branch circuits, the
voltage drop across each feeder circuit and branch circuit should be calculated. It is normally not
necessary to the calculate voltage drop across the service conductors since they are normally only a
short distance and it is the power company’s responsibility to provide the nominal voltage at the service
point. The voltage drop calculation will determine the amount of voltage lost along the conductors.
Calculating the voltage drop across the system is important as it will ensure the voltage is sufficient to
properly operate all ITS devices, to avoid inefficient operations as a result of excessive amounts of
power being dissipated across the electrical system.
The electrical conductors carrying current to the service cabinet have resistance. The resistance of the
conductors depends on the length of the conductors, size (gauge) of the conductors, and conductor
material. When current flows through the conductors, the voltage drops along the length of the
conductor, which results in a lower voltage at the end of the circuit. A similar voltage drop occurs in the
return current of the neutral wire and is additive to the total voltage drop for a 2-wire circuit or
unbalanced 3-wire circuit. If the resistance of the conductor is too high for the amount of current
flowing through it, the voltage lost will be too high.

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When providing power to an ITS device, the NEC recommends that the maximum voltage drop across
the combined feeder and branch circuits not exceed 5% and the maximum individual voltage drop
across the feeder circuit or the branch circuit not exceed 3%. In some instances, MnDOT may elect to
utilize a maximum voltage drop of 5% or greater for the individual feeder circuit and branch circuit. In
these instances, the designer should obtain approval from MnDOT as well as provide detailed design
calculations for the continuous and peak power demand for the ITS application or device.
The voltage drop for a circuit is calculated as follows:

Total Voltage Drop = Voltage Drop on Highest Current Leg + Voltage Drop on Neutral

Voltage Drop = Current Load * Distance Factor *Resistance of Wire

Resistance of Wire – in ohms/1000 feet (from Table 3-1)

Current Load – in amps

Distance Factor = Distance/1000

Distance – is total length of wire (including slack)

For a 120 volt 2-wire circuit:

Current on Leg = Current on Neutral

Voltage Drop on Leg = Voltage Drop on Neutral

For a 120/240 volt 3-wire circuit with a balanced load:

Voltage Drop on Neutral = 0 volts (because there is no current on the neutral)

It is desirable to balance the loads on each leg of a 120/240 volt 3-wire circuit because it is more
efficient since there is no additional voltage drop across the neutral. Having a system with balanced
loads also extends the service life of transformers.
The preferred maximum voltage drop is calculated as follows:

Preferred maximum voltage drop = preferred % drop * volts

Preferred % drop = 3% for branch circuits, 3% for feeder circuits, and 5% total for branch with
highest voltage drop and feeder circuits

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Volts = voltage of circuit (typically 120 volts for 120/240 volt RTMC circuits)

When the voltage drop across an electrical circuit providing power to an ITS application exceeds the
maximum recommended value, the designer may increase the size of the electrical conductors or
increase the voltage of the circuit. When the size of electrical conductors are increased, the overall
electrical resistance of the circuit will decrease, which results in a corresponding drop in the voltage lost
across the circuit. Increasing the voltage at which electrical current is transmitted through the electric
conductors will require use of a step-up transformer placed near the transformer or service drop and a
step-down transformer placed near the ITS device location. MnDOT has a strong preference for
increasing the size of the electrical conductors as opposed to using a step-up and step-down
transformer, which is only used in extenuating circumstances and requires MnDOT approval.
Table 3-3 shows the maximum preferred amp load for a particular wire size and wire length carrying 120
volts and an unbalanced load. Table 3-4 shows the maximum preferred amp load for a particular wire
size and wire length carrying 120/240 volts and a balanced load.

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Table 3-2: Typical MnDOT ITS Device Power Requirements

Component(s) Amp Load for Voltage Drop Calculations ** Notes
CABINET LOADS
334 and 340 Cabinet 2.0
Pole Cabinet with NID 0.5
Pole Cabinet with video camera 1.5
E-ZPass Reader with Beacon 1.0
Shelter 2-P 35.0 includes 5 amp GFCI outlet
DMS *
F8C1-20 / R8C1-20 5.0 32 x 112 pixel configuration
F8C2-20 / R8C2-20 10.0 64 x 112 pixel configuration
W18C3-20 2-P 18.0 96 x 240 pixel configuration
W18C4-20 2-P 21.0 128 x 240 pixel configuration
W24C3-20 2-P 22.0 96 x 336 pixel configuration
F14C1-20 / R14C1-20 10.0 32 x 208 pixel configuration
F14C2-20 / R14C2-20 16.5 64 x 208 pixel configuration
F14C3-20 / R14C3-20 2-P 13.5 96 x 208 pixel configuration
F18C1-20 / R18C1-20 11 32 x 256 pixel configuration
F18C2-20 / R18C2-20 2-P 11.0 64 x 256 pixel configuration
F18C3-20 / R18C3-20 2-P 15.5 96 x 256 pixel configuration
W30C3-20 2-P 29.0 96 x 432 pixel configuration
W30C4-20 2-P 35.0 128 x 432 pixel configuration
W40C3-20 2-P 40.0 96 x 592 pixel configuration
W40C4-20 2-P 50.0 128 x 592 pixel configuration
* - DMS feature description based on Ledstar model number
Model number - ABBCD-EE
A - W - walk-in access, F - front access, or R - rear access
BB - width in feet
C - color
D - # of rows of text
EE - pixel pitch (in millimeters)
** - 2-P ##.# is two-pole with ##.# amps per leg

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Table 3-3: Maximum Preferred Amperage for 3% Voltage Drop with 120 Volts Unbalanced Load 1
50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800
Wire Size (AWG) Ft Ft Ft Ft Ft Ft Ft Ft Ft Ft Ft Ft Ft Ft Ft Ft
14 14.0 7.0 4.7 3.5 2.8 2.3 2.0 1.8 1.6 1.4 1.3 1.2 1.1 1.0 0.9 0.9
12 20.0 11.1 7.4 5.6 4.4 3.7 3.2 2.8 2.5 2.2 2.0 1.9 1.7 1.6 1.5 1.4
10 30.0 17.6 11.8 8.8 7.1 5.9 5.0 4.4 3.9 3.5 3.2 2.9 2.7 2.5 2.4 2.2
8 45.0 28.1 18.8 14.1 11.3 9.4 8.0 7.0 6.3 5.6 5.1 4.7 4.3 4.0 3.8 3.5
6 65.0 43.9 29.3 22.0 17.6 14.6 12.5 11.0 9.8 8.8 8.0 7.3 6.8 6.3 5.9 5.5
4 85.0 69.2 46.2 34.6 27.7 23.1 19.8 17.3 15.4 13.8 12.6 11.5 10.7 9.9 9.2 8.7
3 100.0 85.7 57.1 42.9 34.3 28.6 24.5 21.4 19.0 17.1 15.6 14.3 13.2 12.2 11.4 10.7
2 115.0 112.5 75.0 56.3 45.0 37.5 32.1 28.1 25.0 22.5 20.5 18.8 17.3 16.1 15.0 14.1
1 130.0 130.0 92.3 69.2 55.4 46.2 39.6 34.6 30.8 27.7 25.2 23.1 21.3 19.8 18.5 17.3
0 150.0 150.0 120.0 90.0 72.0 60.0 51.4 45.0 40.0 36.0 32.7 30.0 27.7 25.7 24.0 22.5
00 175.0 175.0 150.0 112.5 90.0 75.0 64.3 56.3 50.0 45.0 40.9 37.5 34.6 32.1 30.0 28.1
000 200.0 200.0 200.0 150.0 120.0 100.0 85.7 75.0 66.7 60.0 54.5 50.0 46.2 42.9 40.0 37.5

850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500 1550 1600
Wire Size (AWG) Ft Ft Ft Ft Ft Ft Ft Ft Ft Ft Ft Ft Ft Ft Ft Ft
14 0.8 0.8 0.7 0.7 0.7 0.6 0.6 0.6 0.6 0.5 0.5 0.5 0.5 0.5 0.5 0.4
12 1.3 1.2 1.2 1.1 1.1 1.0 1.0 0.9 0.9 0.9 0.8 0.8 0.8 0.7 0.7 0.7
10 2.1 2.0 1.9 1.8 1.7 1.6 1.5 1.5 1.4 1.4 1.3 1.3 1.2 1.2 1.1 1.1
8 3.3 3.1 3.0 2.8 2.7 2.6 2.4 2.3 2.3 2.2 2.1 2.0 1.9 1.9 1.8 1.8
6 5.2 4.9 4.6 4.4 4.2 4.0 3.8 3.7 3.5 3.4 3.3 3.1 3.0 2.9 2.8 2.7
4 8.1 7.7 7.3 6.9 6.6 6.3 6.0 5.8 5.5 5.3 5.1 4.9 4.8 4.6 4.5 4.3
3 10.1 9.5 9.0 8.6 8.2 7.8 7.5 7.1 6.9 6.6 6.3 6.1 5.9 5.7 5.5 5.4
2 13.2 12.5 11.8 11.3 10.7 10.2 9.8 9.4 9.0 8.7 8.3 8.0 7.8 7.5 7.3 7.0
1 16.3 15.4 14.6 13.8 13.2 12.6 12.0 11.5 11.1 10.7 10.3 9.9 9.5 9.2 8.9 8.7
0 21.2 20.0 18.9 18.0 17.1 16.4 15.7 15.0 14.4 13.8 13.3 12.9 12.4 12.0 11.6 11.3
00 26.5 25.0 23.7 22.5 21.4 20.5 19.6 18.8 18.0 17.3 16.7 16.1 15.5 15.0 14.5 14.1
000 35.3 33.3 31.6 30.0 28.6 27.3 26.1 25.0 24.0 23.1 22.2 21.4 20.7 20.0 19.4 18.8

1
Values in tables are based on copper conductors with wire characteristics listed in Table 3-1.

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Table 3-4: Maximum Preferred Amperage for 3% Voltage Drop with 120/240 Volts Balanced Load1
50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800
Wire Size (AWG) Ft Ft Ft Ft Ft Ft Ft Ft Ft Ft Ft Ft Ft Ft Ft Ft
14 15.0 14.0 9.3 7.0 5.6 4.7 4.0 3.5 3.1 2.8 2.5 2.3 2.2 2.0 1.9 1.8
12 20.0 20.0 14.8 11.1 8.9 7.4 6.3 5.6 4.9 4.4 4.0 3.7 3.4 3.2 3.0 2.8
10 30.0 30.0 23.5 17.6 14.1 11.8 10.1 8.8 7.8 7.1 6.4 5.9 5.4 5.0 4.7 4.4
8 45.0 45.0 37.5 28.1 22.5 18.8 16.1 14.1 12.5 11.3 10.2 9.4 8.7 8.0 7.5 7.0
6 65.0 65.0 58.5 43.9 35.1 29.3 25.1 22.0 19.5 17.6 16.0 14.6 13.5 12.5 11.7 11.0
4 85.0 85.0 85.0 69.2 55.4 46.2 39.6 34.6 30.8 27.7 25.2 23.1 21.3 19.8 18.5 17.3
3 100.0 100.0 100.0 85.7 68.6 57.1 49.0 42.9 38.1 34.3 31.2 28.6 26.4 24.5 22.9 21.4
2 115.0 115.0 115.0 112.5 90.0 75.0 64.3 56.3 50.0 45.0 40.9 37.5 34.6 32.1 30.0 28.1
1 130.0 130.0 130.0 130.0 110.8 92.3 79.1 69.2 61.5 55.4 50.3 46.2 42.6 39.6 36.9 34.6
0 150.0 150.0 150.0 150.0 144.0 120.0 102.9 90.0 80.0 72.0 65.5 60.0 55.4 51.4 48.0 45.0
00 175.0 175.0 175.0 175.0 175.0 150.0 128.6 112.5 100.0 90.0 81.8 75.0 69.2 64.3 60.0 56.3
000 200.0 200.0 200.0 200.0 200.0 200.0 171.4 150.0 133.3 120.0 109.1 100.0 92.3 85.7 80.0 75.0

850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500 1550 1600
Wire Size (AWG) Ft Ft Ft Ft Ft Ft Ft Ft Ft Ft Ft Ft Ft Ft Ft Ft
14 1.6 1.6 1.5 1.4 1.3 1.3 1.2 1.2 1.1 1.1 1.0 1.0 1.0 0.9 0.9 0.9
12 2.6 2.5 2.3 2.2 2.1 2.0 1.9 1.9 1.8 1.7 1.6 1.6 1.5 1.5 1.4 1.4
10 4.2 3.9 3.7 3.5 3.4 3.2 3.1 2.9 2.8 2.7 2.6 2.5 2.4 2.4 2.3 2.2
8 6.6 6.3 5.9 5.6 5.4 5.1 4.9 4.7 4.5 4.3 4.2 4.0 3.9 3.8 3.6 3.5
6 10.3 9.8 9.2 8.8 8.4 8.0 7.6 7.3 7.0 6.8 6.5 6.3 6.1 5.9 5.7 5.5
4 16.3 15.4 14.6 13.8 13.2 12.6 12.0 11.5 11.1 10.7 10.3 9.9 9.5 9.2 8.9 8.7
3 20.2 19.0 18.0 17.1 16.3 15.6 14.9 14.3 13.7 13.2 12.7 12.2 11.8 11.4 11.1 10.7
2 26.5 25.0 23.7 22.5 21.4 20.5 19.6 18.8 18.0 17.3 16.7 16.1 15.5 15.0 14.5 14.1
1 32.6 30.8 29.1 27.7 26.4 25.2 24.1 23.1 22.2 21.3 20.5 19.8 19.1 18.5 17.9 17.3
0 42.4 40.0 37.9 36.0 34.3 32.7 31.3 30.0 28.8 27.7 26.7 25.7 24.8 24.0 23.2 22.5
00 52.9 50.0 47.4 45.0 42.9 40.9 39.1 37.5 36.0 34.6 33.3 32.1 31.0 30.0 29.0 28.1
000 70.6 66.7 63.2 60.0 57.1 54.5 52.2 50.0 48.0 46.2 44.4 42.9 41.4 40.0 38.7 37.5

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BREAKER SIZING
Per the NEC, all electrical circuits require overcurrent protection. Circuit breakers help protect against
excess current as the result of an overload or short-circuit. When the power reaches a certain level, the
circuit breaker is designed to automatically interrupt the flow of power to prevent fires, damage to
wiring or electronics, and personal electrocution. In order to function properly, the circuit breaker must
be sized appropriately. To be sized appropriately, the circuit breaker should be designed to handle a
minimum of 125% of the maximum continuous load and 100% of the non-continuous load. Continuous
loads are loads that are expected to last three or more hours while non-continuous loads are those
lasting less than three hours.
Circuit breakers typically used in service cabinets by MnDOT for ITS applications are noted below:
• 334 series cabinet: 30 amp single pole
• NID and/or camera with pole cabinet: 15 amp single pole
• Gate arm: 15 amp double pole
• 18’ wide Ledstar DMS: 30 amp double pole
• 30’ wide Ledstar DMS: 60 amp double pole
• 40’ wide Ledstar DMS: 100 amp double pole
Main circuit breakers typically used in service cabinets:
• Standard service cabinet: 60 amp double pole main
• Service cabinet serving a shelter, a 40’ DMS, or two 30’ DMS: 100 amp double pole main
EXAMPLE CALCULATIONS
Several factors need to be considered when locating an ITS device including the source of power
location and resulting conductor and conduit sizes required to serve the ITS devices at their required
locations. If the cables become too large it is often desirable to obtain a source of power located closer
to the site. Design of the power system required for an individual ITS location will generally follow the
design steps and calculations outlined below.
1) Identify an available power source and determine its suitability to provide power to the
proposed ITS site. Factors that impact suitability of the power source is whether it is located on
MnDOT right-of-way and if the required voltage is able to be provided. The power source may
be an existing electric service or require the installation of a new electric service.
2) The following needs to be determined for the feeder and branch circuits:
• Current load required for each device
• Combined current load of each circuit
• Minimum conductor and circuit breaker size for the current load
• Any increase in conductor size required to address excessive voltage drop
Example (see Figure 3-7): If there is a service cabinet (metered) located just on MnDOT property
that provides power to a service cabinet type special (non-metered) located 400 feet away
where branch circuits serve a 334MP Control Cabinet (located 250’ from service cabinet type
special) and DMS (Ledstar model W30C4-20 located 200’ from service cabinet type special), the
following circuits need to be considered as a part of the design:

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• Feeder circuit #1 is a 120/240 volt circuit that serves a main 2-pole circuit breaker in the
service cabinet type special.
• Branch circuits from service cabinet type special are as follows:
• Branch circuit #2 (DMS) is a 120/240 volt branch circuit that serves the DMS
with a 2-pole circuit breaker located in the service cabinet type special
• Branch circuit #3 (334MP Control Cabinet) is a 120 volt branch circuit that serves
the 334MP Control Cabinet with a 1-pole circuit breaker located in the service
cabinet type special
3) Determine the total current load required for the feeder circuit and each branch circuit including
the cabinet, all internal equipment, and all ITS devices connected to the cabinet. Typical MnDOT
ITS device current loads are included in Table 3-2.
Using Table 3-2 the following are the current load required for the branch circuits:
• Branch circuit #2 (DMS - Ledstar model W30C4-20): 35 amps on each leg
• Branch circuit #3 (334 MP Control Cabinet): 2 amps (including all internal components)
Calculate the current required for an unbalanced 3-wire circuit (based on this example):
• Feeder circuit #1 current load on highest current leg = current on branch circuit #2 +
current on branch circuit #3
• Feeder circuit #1 current load on highest current leg = 35 amps + 2 amps = 37
amps
• Feeder circuit #1 current load on other leg = current on branch circuit #2
• Feeder circuit #1 current load on other leg = 35 amps (the 2 amps from branch
circuit #3 only is applied to 1 leg since branch circuit #3 is a 120 volt 2-wire
circuit
• Feeder circuit #1 current load on the neutral = current load on highest current leg –
current load on other leg
• Feeder circuit #1 current load on neutral = 37 amps - 35 amps = 2 amps
For items not included in Table 3-2, the current load needs to be determined by contacting the
manufacturer, reviewing product cut sheets, or taking actual measurements.
4) Calculate the voltage drop across the electrical conductors. If the voltage drop exceeds
recommended values, the size of the electrical conductors should be increased.

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Figure 3-7: Voltage Drop Example

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Calculating the voltage drop and size the conductors to not exceed the maximum preferred
voltage drop for the feeder and branch circuits as follows:
Branch circuit #2 (DMS):
Assume a #6 AWG wire initially (see Wire Gauge for minimum conductor size).
Voltage drop on highest current leg = 35 * [(210)/1000] * 0.41
Current load = 35 amps from step 3
Distance factor = Distance/1000
Distance = 200 feet so use 210 feet to account for slack
Resistance of wire = 0.41 from Table 3-1 using value for #6 AWG
Voltage drop on highest current leg = 3.01 volts
Voltage drop on neutral = 0 volts
Total voltage drop = 3.01 volts + 0 volts
Total Voltage drop = 3.01 volts
Does the voltage drop exceed the preferred maximum voltage drop?
Preferred maximum voltage drop = .03 * 120
Preferred % drop = 3% since this circuit is a branch circuit
Voltage of circuit = 120/240 volts for this DMS
Maximum preferred voltage drop = 3.60 volts
Since 3.0 is less than the maximum preferred voltage drop of 3.6, the #6 AWG wire size
is adequate.
Branch circuit #3 (334 MP Control Cabinet):
Assume a #8 AWG wire initially (see Wire Gauge for minimum conductor size).
Voltage drop on highest current leg = 2 * [(265)/1000] * 0.64
Current load = 2 amps from step 3
Distance factor = Distance/1000
Distance = 250 feet so use 265 feet to account for slack
Resistance of wire = 0.64 from Table 3-1 using value for #8 AWG
Voltage drop on highest current leg = 0.34 volts
Voltage drop on neutral = 0.34 volts
Total voltage drop = 0.34 volts + 0.34 volts = 0.68 volts
Total Voltage drop = 0.68 volts
Does the voltage drop exceed the preferred maximum voltage drop?

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Preferred maximum voltage drop = .03 * 120

Preferred % drop = 3% since this circuit is a branch circuit
Voltage of circuit = 120 volts for 334 MP Control Cabinet
Maximum preferred voltage drop = 3.60 volts
Since 0.68 is less than the maximum preferred voltage drop of 3.6, the #8 AWG wire is
adequate.
Feeder Circuit #1 (feeder between service cabinet and service cabinet type special):
Assume a #6 AWG wire initially (see Wire Gauge for minimum conductor size).
Voltage drop on highest current leg = 37 * [(420)/1000] * 0.41
Current load = 37 amps from step 3
Distance factor = Distance/1000
Distance = 400 feet so use 420 feet to account for slack
Resistance of wire = 0.41 from Table 3-1 using value for #6 AWG
Voltage drop on highest current leg = 6.37 volts
Voltage drop on neutral = 2 * [(420)/1000] * 0.41
Current load = 2 amps from step 3
Distance factor = Distance/1000
Distance = 400 feet so use 420 feet to account for slack
Resistance of wire = 0.41 from Table 3-1 using value for #6 AWG
Voltage drop on neutral = 0.34 volts
Total voltage drop = 6.37 volts + 0.34 volts = 6.71 volts
Total Voltage drop = 6.71 volts
Does the voltage drop exceed the preferred maximum voltage drop?
Preferred maximum voltage drop = .03 * 120
Preferred % drop = 3% since this circuit is a feeder circuit
Voltage of circuit = 120 volts
Maximum preferred voltage drop = 3.60 volts
Increase the wire size to #2 AWG.
Voltage drop on highest current leg = 37 * [(420)/1000] * 0.16
All items remain the same except:
Resistance of wire = 0.16 from Table 3-1 using value for #4 AWG
Voltage drop on highest current leg = 2.49 volts

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Voltage drop on neutral = 2 * [(420)/1000] * 0.16

Voltage drop on neutral = 0.13 volts
Total voltage drop = 2.49 volts + 0.13 volts = 2.62 volts
Total Voltage drop = 2.62 volts
Does the voltage drop exceed the preferred maximum voltage drop?
Since 2.62 volts is less than the maximum preferred voltage drops of 3.60, the #2 AWG
wire is adequate.
Does the total voltage drop on Feeder Circuit #1 and Branch Circuit #2 exceed 5%?
2.62 volts + 3.01 volts = 5.63 volts
Since 5.63 volts < 0.05 * 120 volts = 6 volts the total voltage drop is okay.
Does the total voltage drop on Feeder Circuit #1 and Branch Circuit #3 exceed 5%?
2.62 volts + 0.68 volts = 3.30 volts
Since 3.30 volts < 0.05 * 120 volts = 6 volts the total voltage drop is okay.
The tables below present the current load and voltage drop calculated above for each of the
circuits.
Circuit Current Load (Amps) Voltage Drop (Volts)
Feeder Circuit #1 37.0 2.62
Branch Circuit #2 (DMS) 35.0 3.01
Total 5.63

Circuit Current Load (Amps) Voltage Drop (Volts)

Feeder Circuit #1 37.0 2.62
Branch Circuit #2 (DMS) 2.0 0.68
Total 3.30

5) Determine the circuit breaker sizes for each circuit.

Select circuit breakers based on Breaker Sizing subsection:
Feeder Circuit #1 = 60 amp double pole since it is serving a standard service cabinet type
special.
Branch circuit #2 (DMS) = 60 amp double pole since it is serving a 30’ wide DMS
Branch circuit #3 (334 MP Control Cabinet) = 30 amp single pole since it is serving a 334
series cabinet
Current loads on each circuit from step 3 above:
Feeder circuit #1 = 37 amps

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Branch circuit #2 (DMS) = 35 amps

Branch circuit #3 (334 MP Control Cabinet) = 2 amps
Verify the current load on each circuit is less than the breaker rating:
Feeder circuit #1 - 37 amps * 125% = 46.3 amps < 60 amps
Branch circuit #2 (DMS) - 35 amps * 125% = 43.8 amps < 60 amps
Branch circuit #3 (334 MP Control Cabinet) - 2 amps * 125% = 2.5 amps < 30 amps
The current loads are multiplied by 125% because these particular loads are continuous
loads.
Since all current loads are less than the circuit breaker sizes selected, the circuit breakers
selected are acceptable.
6) Confirm the electrical conductors selected for each circuit in step 4 have a higher ampacity
rating than the circuit breakers selected in Step 5.
Wire sizes from step 4:
Feeder circuit #1 = #2 AWG wire
Branch circuit #2 (DMS) = #6 AWG wire
Branch circuit #3 (334 MP Control Cabinet) = #8 AWG wire
Review Table 3-1 to obtain ampacity rating for the conductors used:
Feeder circuit #1 = 115 amps
Branch circuit #2 (DMS) = 65 amps
Branch circuit #3 (334 MP Control Cabinet) = 45 amps
Verify the ampacity is more than the breaker rating:
Feeder circuit #1 - 115 amps > 60 amps
Branch circuit #2 (DMS) - 65 amps > 60 amps
Branch circuit #3 (334 MP Control Cabinet) - 45 amps > 30 amps
Since the ampacity on all three circuits is greater than the breaker rating, the wire sizes selected
are adequate.
If the ampacity is less than the circuit breaker rating, then the breaker rating needs to be
reduced and/or the wire size needs to be increased.
The designer needs to verify the lugs of the circuit breaker used fit the size of the conductors
being terminated at the lugs.
The calculations above show the manual voltage drop calculation process. Table 3-3 and Table
3-4 can also be used to determine the wire size for a particular conductor length and size for a
circuit carrying 120 volts with an unbalanced load and 120/240 volts with a balanced load,
respectively.

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SURGE PROTECTION
Lightning strikes are the most common cause of power surges to the ITS field system. The resulting
voltage surges can propagate long distances along the cable to the connected devices. In order to
protect the related ITS deployment, appropriate surge protection measures must be provided for the ITS
devices. These measures can be broken down into four components:
• Lightning rods at the top of or near the support structure
• Grounding system, usually consisting of one or more grounding rods
• Surge suppression hardware in the control cabinet
• Grounding conductor bonding the three above components
The provision of lightning rods is preferred for deployments involving great heights, such as video
cameras and radio antenna at the top of tall poles that “stand out” among the surrounding landscape
and vegetation. The use of lightning rods is usually omitted for deployments involving relatively low
heights and where taller structures are present nearby.
In general, surge suppressors provide protection from energy (electric) surges by diverting and draining
the excess (surge) energy to surrounding soil. It is therefore pertinent to combine the use of surge
suppressors with a properly designed grounding conductor and grounding system. DMS, pole cabinets,
and 334 series cabinets have digital surge suppressor units built in to protect against spikes.
The provision of one or more lightning rods over the ITS device, in conjunction with a grounding
conductor(s), can often help to divert the lightning discharges away from the field device assembly.
Lightning abatement measures such as this are only effective if the lightning rod, related terminations,
and the grounding conductors are sufficiently robust to conduct and to survive lightning discharges.
Telecommunications cables and sensor cables from nearby locations, just like the utility power cable,
are subject to the same possibility of lightning strikes. The requirement for appropriate surge protection
measures must therefore be extended to all cables brought into the cabinet of all ITS deployments.
A proper grounding arrangement must be provided at the support structure and at the controller
cabinet for the system. Where the controller cabinet is installed at or close to the base of the support
structure, both the support structure and the cabinet may be bonded to the same grounding system.
It is important that the related grounding system is able to disperse the electric charge from the
lightning strike quickly to the surrounding earth mass. This requirement is translated in the performance
requirement on the grounding system to have “grounding resistance of 25 ohms or less.”
MnDOT uses two 5/8-inch, 15-foot, one-piece solid copper rods for grounding. When multiple rods are
needed to achieve the required maximum ground resistance (25 ohms), space the ground rods at 6’
apart from each other or per NEC recommendations, whichever is greater.
Grounding rods, systems, and testing procedures are specified in the NEC. The designer should assess
the site environmental conditions to determine if the grounding system identified in the 408
specifications is sufficient for the device location. Some devices require more robust grounding
requirements, such as video cameras located at the tops of hills and mounted to high structures.
ITS systems usually include sensitive electronics located in an outdoor environment and mounted on
metal poles. A lightning storm can cause the equipment to fail if it is not properly protected. Every

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control cabinet should have a quality, properly rated, solid state surge suppression device located where
the power conductors terminate in the cabinet. In addition to the grounding required by the NEC at the
service cabinet, the control cabinet should also have a grounding conductor going from its equipment
ground bus to a ground rod. The ground rod may be the one used by the service cabinet or a different
one if the cabinets are not co-located. If the system includes tall mounting poles and is not connected by
metal conduit, the pole installation should also include a ground rod. Per the NEC, it is essential that all
metal cabinets, poles, housings, conduits, etc. be connected into a properly bonded and grounded
system. All communications and video field cables should have surge suppression at both ends where
they enter a cabinet. Unfortunately, experience has shown that systems that are not properly grounded
or protected from surges will not last long in the outdoor roadside environment.
High quality surge suppression is very important and typically costs $350-$400 per cabinet (good
grounding is critical). Without surge suppression there can be a loss of equipment.
POWER OVER ETHERNET
Power over Ethernet (PoE) is an alternate method used to power a device or infrastructure using direct
current over twisted-pair copper Ethernet cabling. PoE allows a single cable to transmit both data and
power, eliminating the need for two separate cables. The Institute of Electrical and Electronics Engineers
(IEEE) has developed a series of standards that define different types of PoE technology. Table 3-5
includes a list of different PoE standards and the maximum power than can be provided over the
Ethernet cable.
Table 3-5: Power Over Ethernet Parameters
Maximum Power Maximum Transmission
IEEE Standard PoE Designation
(watts) Distance (feet) 2
802.3af
PoE 15.4 250
802.3af Type 1
802.3at Type 2 PoE+ 30 250
802.3bt Type 3 PoE++ 60 250
802.3bt Type 4 PoE++ (High Power) 100 250

Cat 5E twisted-pair copper cable used by MnDOT supports PoE. In order to utilize PoE, the switch port
that the twisted-pair copper cable is connected to must also be capable of supporting PoE. Many
wireless radios utilize PoE, as do a few different ITS devices including video cameras and vehicles
detection. Pan-tilt-zoom (PTZ) cameras need PoE++ while static cameras use PoE+.

3.1.9. Alternative Energy Options

SOLAR
In remote rural areas, obtaining power from an electric service provider can be very expensive if there
are no electrical facilities or infrastructure in the immediate area. For low-power ITS applications, and
even a few higher-power applications, solar power may be an option. Solar power may be considered
when obtaining power from a nearby electric service provider is not practical or is cost prohibitive. Solar

2 Per the IEEE standard, the maximum transmission distance is 328 feet; however, MnDOT utilizes a maximum
transmission distance of 250 feet for all PoE devices.

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power can be versatile and is environmentally friendly, but several criteria should be evaluated when
considering it as an option. When designing any ITS application that will utilize solar power, the design
should be reviewed by an electrical engineer to ensure the system is sized appropriately. As an alternate
to developing an individual design for the specific location, an off-the-shelf system may also be an
option depending on the desired ITS application.
When designing an ITS device or system that will utilize solar power, several important factors should be
considered. These factors include calculating the total power required by the system at any time of day,
during any weather conditions, and during any month of the year; the frequency or percent of time that
the system will be operational; the length of time the system must operate in the absence of any
sunlight; and any terrain or vegetation that might impact operations today or in the future. Generally,
when designing a solar power system for an ITS deployment, it is a good practice to overdesign the
system to help counteract any unexpected weather conditions that might impact power generation.
Another important consideration is the life-cycle replacement costs required to procure and install
replacement batteries on average every three years.
During the winter months in Minnesota, the total hours of sunlight per day are limited, and there are
often extended periods without sunlight that last multiple days. In these situations, the lack of available
sunlight can severely impact the amount of power generated by solar cells and stored by the local
batteries. These problems can be further exacerbated when snow and ice accumulate on the solar
panels, further limiting their exposure to direct sunlight. Because of these limitations, solar is generally
only used on a limited basis for low-power ITS applications (flashing beacons, blank-out signs, and some
traffic detectors). Solar panels are more efficient at lower temperatures, but batteries typically lose
capacity as the temperature drops. Off-the-shelf solar power systems are available for many low-
powered ITS applications, which can save time and money in the design and installation process.
Certain ITS applications, including video cameras, may in limited situations be powered with solar but
may have reduced up-time during the winter months and will require a lot more maintenance than a
typical AC-powered system. The designer needs to design the solar array and battery system based on
the design loads and anticipated weather conditions. ITS applications that utilize solar power should
include remote monitoring capabilities to allow MnDOT to remotely check the status of the solar cells
and batteries without having to wait until the system fails to perform a field visit.
WIND
Wind generated power is another option that can be used to provide power to an ITS device. Wind
power should only be used when all other options for obtaining power have been exhausted, including
obtaining power from an electric service provider or from solar. Due to the unpredictability and
inconsistency of wind generated power, MnDOT does not consider it a reliable power source.
Similar to solar generated power, ITS applications that utilize wind power require batteries to store the
power generated by the wind turbine for future use. Extended periods of no or little wind may result in
a significant or complete draw down of available power stored in the batteries. During the winter
months, colder temperatures can reduce overall battery capacity, which will further reduce the power
available to operate the ITS device. Because of these limitations, wind power is generally only used as a
last resort and should not be the primary power source for an ITS device. Wind power may, however, be
used to complement another power source, such as solar, to provide a second, redundant source of
power generation. Wind power generation typically requires infrastructure that has numerous moving

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parts. These moving parts require continuous maintenance, which increases the cost and staff time
required to keep the system fully operational, especially when combined with battery maintenance
and/or life-cycle replacement.
When designing a wind power system for an ITS deployment, it is good practice to overdesign the
system to help counteract the impacts of a drawdown of power during extended periods of no or little
wind. Wind turbines typically generate more power the higher they are mounted, which can create
additional maintenance challenges. Off-the-shelf systems for wind power generation are available and,
with MnDOT approval, may be considered when providing wind generated power to an ITS device.
BATTERIES
ITS applications that utilize solar and/or wind turbines to generate power will require an array of
batteries connected to the power generation system in order to capture and store power for future use.
The total number of batteries required for an individual ITS application will vary depending on the
power required to operate the ITS application, the number and type of batteries utilized, the duration of
time the ITS application will need to remain fully functional under 100% battery power, the ambient
temperature and battery correction factor, the age of the battery, and the depth and duration of battery
discharge cycles. MnDOT typically utilizes 100A-hour lead acid batteries for power storage. When
selecting and designing an ITS application that will require battery power storage, the designer should
consider long term battery maintenance costs and life cycle replacement. The estimated life of a typical
100A-hour battery will vary but, on average, MnDOT has observed an average lifespan of three years.
Trailers use 6V batteries in a 12V array and static equipment uses 12V batteries in a 24V array.
BACKUP POWER
ITS applications and network communications equipment that support critical MnDOT functions or life
safety services may require that a backup power system be included in the design. There are a few
different technologies and systems used by MnDOT to provide backup power including diesel and
propane generators and uninterruptable power supplies (UPS). Selecting the type of backup power
system will vary depending on the type of ITS application and/or network communications being
powered. Sizing the backup power system will utilize many of the same design parameters outlined in
the prior section for sizing a battery system. The designer needs to be aware that certain proposed ITS
applications or network equipment will require backup power, they should consult with the MnDOT
project manager.

3.2. Communications
Communication protocols for ITS are being developed under the National Transportation
Communications for ITS Protocol (NTCIP) standards development effort. These are open (non-
proprietary), industry-based standards that make it possible for ITS devices from multiple vendors to
exchange information — both with each other and with a central system — through a common
communications interface. There are many NTCIP standards, each relating to one or more ITS
applications.

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3.2.1. Types
SERIAL
Many older ITS devices, and some new ITS devices, utilize serial communications. Serial communications
can be either uni- or bi-directional and transmit one communication bit at a time. Some ITS devices
utilize serial communications but can be connected via an Ethernet cable when a serial to Ethernet
converter is used. Detector cards used by MnDOT in some traffic signal and ITS cabinets utilize serial
communications. Additionally, the Wavetronix vehicle detector used by MnDOT utilizes a serial to
Ethernet converter. ITS devices that utilize serial communications typically use communication cables
that include a number of different types of connectors including RS-232, RS-422, and RS-485.
TRANSMISSION CONTROL PROTOCOL (TCP)/INTERNET PROTOCOL (IP)
All new ITS devices installed by MnDOT are connected to the statewide communications network using
TCP/IP communications. TCP/IP or Transmission Control Protocol/Internet Protocol is a series of
communications protocols used to connect devices on a network. TCP/IP governs how the data is
exchanged. It also includes information on how that data is to be broken up into smaller packets and
how that data should be addressed, transmitted, and routed through the network to its destination.
Each ITS device on the network is then assigned a specific IP address.

3.2.2. Network Topology

Network topology is the general relationship between devices and how data flows throughout the
network.
PHYSICAL
The physical network layer, often referred to as Layer 1, includes physical network hardware (hub,
repeater, media converter, etc.) and communications cables that have no knowledge of the data bytes
or frames being transmitted. Data in a Layer 1 network is transmitted to all hardware ports and across
all communications cables.
LOGISTICAL
Beyond the physical network layer, more advanced networks utilize Layer 2 and Layer 3 technology.
Layer 2, often referred to as the data link layer, provides direct data transfer between two devices
within a network. Layer 2 communications utilize Media Access Control (MAC). Layer 3, often referred to
as the network layer, includes the addition of network routing. MnDOT uses a private Layer 3 network
within the 10.0.0.0 – 10.255.255.255 IP address range.
The following sections are isolated instances of common topologies; however, topologies are typically
combined to develop the actual network. The pros, cons, and typical application by MnDOT of each
topology reviewed is provided in Table 3-6.
Point to Point
Point to point is the simplest topology and is simply two points connected with a direct connection (see
Figure 3-8). Point to point is of limited use in larger installations as it is non-redundant and only connects
two points.

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Figure 3-8: Point to Point Topology Schematic

Daisy Chain
Daisy chain is a type of topology that involves chaining of point to point networks to connect additional
devices. In a daisy chained network, all devices except the end devices pass communications along to
the next device until the information gets to the intended recipient (see Figure 3-9). Daisy chains are
non-redundant and fairly simple.
Figure 3-9: Daisy Chain Topology Schematic

Multi-Drop
Multi-drop is similar to a daisy chain that MnDOT used in twisted pair communications, except that all
devices communicate on a common line (see Figure 3-10). Multi-drop systems require a method to
address collisions as multiple devices are attempting to “talk” at the same time. Multi-drop has been
used on MnDOT ITS systems but is not being used going forward in favor of topologies that support
Ethernet – TCP/IP communications.
Figure 3-10: Multi-Drop Topology Schematic

Ring
Ring topology is similar to a daisy chain except the ends are connected back either through a loop back
or both ends being connected to a router (see Figure 3-11). Rings are redundant; when a device or link is
disabled working devices are kept online. When a ring is “broken,” it becomes two daisy chains. A ring is
only redundant for a single failure. A second failure isolates devices between the breaks.
Figure 3-11: Ring Topology Schematic

Star
A star topology consists of one central device being connected to multiple other devices by a direct
connection (see Figure 3-12). A star is non-redundant; however, when an outage occurs, only devices on
that leg of a star are affected. For MnDOT systems, only one or two devices are placed on a leg of the
star so that the impact is limited if an outage occurs. A star requires less cable as only one line is
required for outlying devices.
MnDOT most often applies a star topology for clusters of nearby devices. The center device may be
placed in a ring and other individual devices are connected to that device. This limits risk since the entire

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ring is not impacted if an outage occurs. However, this physical layout of a star does not work well with
the physical layout of a linear highway ITS system.
Figure 3-12: Star Topology Schematic

Multi-Point/Mesh
A multi-point topology consists of devices that have multiple connections to many other devices (see
Figure 3-13). Multi-point topology is common in newer wireless devices to allow redundancy if a device
becomes unavailable. This is also how the RTMCnet backbone is configured with routers being
connected to multiple other routers. Multi-point is the most redundant topology as each connection has
multiple redundant paths; however, it requires multiple connections to each device and is impractical
for field devices on fiber optic communications in an ITS system.
Figure 3-13: Multi-Point Topology Schematic

Cloud
Using the “cloud” is not a topology in the same sense as the others discussed, but for the ITS designer it
can be thought of in a similar manner. Using the cloud through either a wired or wireless internet
service provider allows communication back to the ATMS or another device through the internet (see
Figure 3-14). Cloud based connections allow for a connection where there is no existing owned
infrastructure; however, it does place reliance on a third party to maintain the connection. In addition,
there are recurring costs for the connection in the form of a monthly service fee. Many connections are
also limited in available bandwidth. It works well for small clusters of isolated devices, or as a temporary
connection.
Figure 3-14: Cloud Topology Schematic

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Table 3-6: Comparison of Common Communication Topologies

Topology Pros Cons MnDOT Example Uses
Point to Point Simple No redundancy, only 2 Point to point wireless
devices connected
Daisy Chain Simple No redundancy can have Rarely used due to lack of
bandwidth issues redundancy
Multi-Drop Allows for devices to be Lower bandwidth, not Optelecom serial modems
off line without disabling compatible with Ethernet (no longer used for new
the network installations)
Ring Redundant as one device Rings are limited in size Most MnDOT field
going off line allows due to spanning tree network is deployed using
communication in the issues in the deployment rings
other direction MnDOT uses
Star Fairly simple No redundancy, but Deployed at interchanges
impacts of an outage are and other clusters of
limited devices
Multi-point Highly redundant Requires lots of ports and RTMCnet Backbone
independent connections
Cloud Accommodates lack of Lower bandwidth than Used to bring small
owned communications typical fiber connection, isolated networks or
infrastructure monthly fee, reliant on devices back to the ATMS.
ISP Also useful for temporary
communications.
Figure 3-15 shows a network drawing of a common MnDOT network configuration. The network
drawings can be obtained using Django. The network in the figure shows both ring and star typologies
being utilized.

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Figure 3-15: Network Diagram

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3.2.3. Technologies
COPPER
Although MnDOT does not typically install new copper communications for long range, twisted pair
copper is still used by MnDOT to communicate with some legacy devices in the field. MnDOT also uses
CAT 6 copper Ethernet cables to communicate over very short distances, such as between cabinets on a
common foundation to a video camera at the top of a fold-down pole. In the past, MnDOT has used six-
pair 19 gauge and 12-pair 19 gauge twisted pair copper communications. New twisted pair copper
communications are typically only installed at locations where existing copper communications are
currently being used and upgrading to newer communications technologies or communications medium
is impractical and/or cost prohibitive. There are a number of different copper communications protocols
including RS-232, RS-422, and RS-485 or VDSL. Characteristics of these communications protocols are
noted in Table 3-7.
Table 3-7: Serial Communications Protocol Characteristics
Maximum Maximum
Comm. Susceptibility
Protocol Cabling Transmission Transmission
Mode to Noise
Distance Rate
RS-232 Single- Full High 50 feet 19.2Kbps
ended Duplex @ 9.6K bps @ 50 feet
RS-422 Single- Full/Half Low 4,000 feet 10Mbps
ended, Duplex @ 9.6K bps @ 50 feet
Multi-
drop
RS-485 Multi- Full/Half Low 4,000 feet 10Mbps
Drop Duplex @ 9.6K bps @ 50 feet

FIBER
All new trunk fiber optic communications installed by MnDOT are single-mode fiber optic cables. In the
past, MnDOT has used multi-mode fiber optic cable. There are several locations in the field where
MnDOT is still using legacy multi-mode fiber optic communications. All MnDOT fiber optic cable
assemblies for fiber optic cable shall comply with USDA RUS CFR 1755.900 (Specification for Filled Fiber
Optic Cables) (https://www.govinfo.gov/content/pkg/FR-1994-07-05/pdf/FR-1994-07-05.pdf). The
designer should refer to the MnDOT Approved Products List for approved fiber optic cable.
ETHERNET
IEEE 802 Ethernet is a standard communications protocol, or set of rules, used for connecting devices in
a Local Area Network (LAN). Many ITS devices and infrastructure used in traffic signal and freeway
management systems utilize Ethernet communications. These devices and equipment often include
Ethernet ports and are connected using Ethernet cables. Ethernet ports allows a direct connection to a
device or piece of equipment without the need for a protocol converter (i.e., serial to Ethernet). It is
important to note that many legacy ITS devices and equipment used by MnDOT, as well as some new
devices, still require the use of some sort of converter. Most new MnDOT ITS designs utilize Ethernet
communications over a ring style network topology, while routers within MnDOT shelters utilize a mesh

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style network topology. The maximum allowable transmission distance for Ethernet cables is 300 feet.
The designer should ensure all network equipment used is field-hardened when not installed in a
climate-controlled environment. MnDOT shelters are climate-controlled environments (see Section 3.5
for more information on shelters).
WIRELESS – SERIAL AND IP
Unlicensed Spread-Spectrum Radio
Spread-spectrum radio wireless communications are commonly used for ITS applications because they
are often cost effective when compared with wired communications. Radios using spread-spectrum
wireless communications do not require Federal Communications Commission (FCC) paperwork and/or
licensing to deploy, which allows them to be easily and quickly installed.
With spread-spectrum wireless communications, the designer must perform a site survey to examine
the line of sight between each radio pair. If the site survey is done in the winter, conditions are liable to
change in the spring when foliage returns to trees. The designer should be careful to consider things
that are likely to change in the future, like annual growth of trees and/or places where new buildings or
infrastructure could be built in the line of site between radios. One additional consideration for spread-
spectrum wireless communications is Radio Frequency Interference (RFI). As the number of wireless
devices exponentially increases over time, the area in which the wireless devices are installed may be
competing with various other sources of ‘noise’ that will diminish the communication capabilities.
Licensed Wireless Radio
In some scenarios, the RFI in an area may be so severe that licensed wireless radio communications are
required in lieu of standard spread-spectrum radios. Licensed wireless communications are generally
reserved for use on backhaul links, over long-distance, or on communications links that require a large
amount of bandwidth. The advantage of a licensed wireless radio is that for the particular frequency (or
frequencies) used, the spectrum must be licensed for a limited use in the area in which the device will
be operating. This prevents other wireless radios from operating on the same frequency and limits the
amount of RFI. Licensed wireless communications are part of an evolving field with multiple competing
technologies. ITS devices currently used by MnDOT that qualify as licensed wireless radios include
Dedicated Short Range Communications (DSRC) and tolling antennas. If either of these devices are
proposed on a project, the designer will need to follow the FCC Part 90 filing process (47 CFR Part 90 –
Land Mobile Radio Service).
CELLULAR
In many places, especially in rural areas, point-to-point wireless communications infrastructure may not
be feasible. In these situations, cellular communications may be utilized to provide connectivity to ITS
devices without having to deploy an extensive communications network. Current cellular technology
relies mostly on Evolution-Data Optimized (EVDO), High Speed Packet Access (HSPA), Evolved High
Speed Packet Access (HSPA+), and Long-Term Evolution (LTE) technologies to deliver download speeds
of up to 50 Megabits per second (Mbps) and upload speeds up to 20 Mbps. Cellular coverage may not
be available in some areas of Minnesota and will vary by cellular carrier. Another possible limitation to
cellular communications is data usage caps set in place by carriers, which can limit applications that can
use cellular communications technology (e.g., video streaming, large data drops, etc.).

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NTCIP 1218
NTCIP 1218 is a new communication protocol that specifies the logical interface between a roadside unit
(RSU) and the controlling management stations. NTCIP 1218 defines information that may be exchanged
across this interface. NTCIP 1218 first identifies the relevant RSU users and their needs, defines
requirements that enable information exchanges that supports those needs, and finally defines the data
objects and meta-data, including the relative structure of that data, necessary to meet these
requirements. This communication protocol will be used for vehicles to connect to the RSU and includes
cellular vehicle-to-everything (C-V2X).

3.2.4. Industrial Field Equipment

AMBIENT TEMPERATURE
The operating ambient temperature range shall be from -34oC (-30oF) to +74oC (+165oF). The storage
temperature range shall be from -45oC (-50oF) to +85oC (+185oF). The rate of change in ambient
temperature shall not exceed 17oC (30oF) per hour, during which the relative humidity shall not exceed
95 percent.
ETHERNET SWITCHES
Ethernet switches are used in wired networks to connect devices located on that network. MnDOT uses
field hardened Ethernet switches in ITS and traffic signal cabinets to connect one or more IP addressable
devices located inside or connected to the cabinet. A field hardened Ethernet switch is designed to
withstand the extreme weather conditions often found in unconditioned environments, similar to that
of an ITS or traffic signal cabinet. Ethernet switches are a State-provided item. Figure 3-16 shows
common ethernet equipment that is used in MnDOT control cabinets. The number of SFP points in the
FO ethernet transport depends on the number of pigtails being terminated in the cabinet (e.g. whether
the daisy-chaining method is being used).
Figure 3-16: Common Ethernet Equipment

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WEB RELAYS
Web relays are increasingly being utilized by MnDOT as part of newer ITS deployments. The purpose of a
web relay is to provide a remotely accessible web interface that can be used to remotely reboot or
power cycle the ITS device. In certain scenarios, rebooting an ITS device that is malfunctioning or that is
locked-up may restore functionality to the device. By remotely resolving the issue, MnDOT is able to
reduce maintenance costs and the staff time required for site visits and field maintenance. Web relays
are standard in rural areas given the initial investment in the relay device is often minimal when
compared with the potential costs associated with multiple field visits required to maintain the device.

3.2.5. Communications Design Considerations

Generally, the key design considerations for Center-to-Field (C2F) communications system for an ITS
deployment are:
• Determine the required communications characteristics, mainly the required bandwidth (in
Kbps or Mbps)
• Investigate what telecommunication options are available at/near the planned deployment
site(s)
• Coordinate with the District to ensure that their requirements are being met
• If using public infrastructure, confirm with telecommunication service providers that the
required communications service is available at the deployment location
• Compare the related costs, benefits, and security aspects of different communications methods
and select the communication method for the site
• Incorporate the chosen communication method into the overall design
• Communications routed through the public World Wide Web must be approved by the RTMC

3.3. Conduit
3.3.1. Types
MnDOT utilizes a number of different conduit types and sizes for ITS related applications. The type and
size of conduit is dependent on the specific location and case for which the conduit will be installed. The
following list includes different types of conduit used by MnDOT:
• Rigid Steel Conduit (RSC) – MnDOT Specification 3801
• Intermediate Metal Conduit – MnDOT Specification 3802
• Non-metallic Conduit (NMC) – MnDOT Specification 3803
• High-Density Polyethylene (HDPE) Conduit
• Poly Vinyl Chloride (PVC) Conduit
• Liquid Tight Flexible Non-Metallic Conduit – MnDOT Specification 3804
• PVC Coated Hot Dipped Galvanized Rigid Steel Conduit – MnDOT Specification 3805
For most underground applications, Schedule 40 NMC satisfies the specifications. For above ground (i.e.
exposed) or under roadway applications, MnDOT utilizes Schedule 80 NMC as the standard. MnDOT also
uses RSC for above ground applications. MnDOT uses PVC Coated Hot Dipped Galvanized Rigid Steel
Conduit when attaching the conduit to a bridge structure. The designer should review the individual
specifications and dimensions for each conduit type to make sure it meets the requirements of the

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particular application and the cables that will be installed inside it. The designer should include a locate
conductor in the conduit whenever an empty non-metallic conduit will be used for future purposes so
that it can be easily located. For conduit under railroad, the designer should use Schedule 80 or as
specified by the railroad authority.

3.3.2. Conduit Fill Ratio

Per the NEC, for conduits with three or more conductors, the total cross-sectional area of all enclosed
wires must be less than 40% of the actual cross-sectional area of the conduit. Therefore, the maximum
conduit fill ratio for all MnDOT power and communications conduit should not exceed 40% of the cross-
sectional area of the conduit. An example conduit fill calculation spreadsheet is included in Table 3-8
that determines the minimum conduit diameter by type (RSC or NMC) based on the total number of
wires/cables of each type to be included in a conduit. The maximum fill requirements are primarily
driven by NEC standards and the need to provide a means of dissipating the heat produced by power
cables inside a conduit. Refer to Table 3-9 for conduit dimensions. Calculations included in Table 3-8 are
based on the conduit dimensions provided in Table 3-9.
Table 3-8: Example Conduit Fill Calculations
Total # of Type of Wire/Cable Wire/Cable Total Cross-
Wires/Cables Wire/Cable Diameter Cross-Sectional Sectional Area
(inches) Area (sq. in.) (sq. in.)

16 2/C No. 14 0.36 0.10174 1.6278

3/C No. 8 0.67 0.35239
3/C No. 20 0.30 0.07065
3/C No. 12 0.46 0.16611
1 3/C No. 14 0.40 0.12560 0.1256
4/C No. 14 0.45 0.15896
4/C No. 18 0.33 0.08549
5/C No. 12 0.59 0.27339
5/C No. 14 0.48 0.18095
2 6/C No. 14 0.53 0.22051 0.4410
12/C No. 12 0.79 0.48992
12/C No. 14 0.71 0.39572
6PR No. 19 0.55 0.23746
FO cable 0.91 0.65037
Micro fiber 0.26 0.05309
Cat 6 0.27 0.05725
No. 3/0 0.67 0.35239
No. 2/0 0.59 0.27326
No. 1/0 0.55 0.23746
No. 1 0.51 0.20418
No. 2 0.43 0.14515
No. 4 0.35 0.09616

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Total # of Type of Wire/Cable Wire/Cable Total Cross-

Wires/Cables Wire/Cable Diameter Cross-Sectional Sectional Area
(inches) Area (sq. in.) (sq. in.)

No. 6 0.30 0.07065

No. 6 Bare 0.16 0.02010
No. 8 0.28 0.06154
No. 10 0.20 0.03140
Total 2.1944

Minimum RSC conduit size = 3.0” diameter

Minimum NMC conduit size = 3.0” diameter
STANDARD CABLES
Table 3-8 above includes the dimensions for various cables used by MnDOT for ITS device installations.
The standard types of the communications and power cables used for MnDOT ITS devices are noted
below:
• DMS: Micro Fiber Optic Pigtail Cable (6MM) and power cables (size varies)
• Video camera: Armored Fiber Optic Pigtail Cable (6SM) and power cables (size varies)
• NID: Armored Fiber Optic Pigtail Cable (6SM) and power cables (size varies)
• Ramp Meter: 6/C No. 14
• Loop Detector: 2/C No. 14
• E-ZPass Toll Reader: Coax Cable LMR 600
Over the past several years, MnDOT has experienced numerous instances of water freezing and
expanding inside a conduit that has resulted in damaged conduit and crushed fiber optic cables. The
designer should consult MnDOT for input on the desired fiber installation method to reduce the
likelihood of this occurring.
Power and fiber cables should be installed in separate conduits except in extreme or unique
circumstances. In these circumstances and with MnDOT approval, power and fiber cables may be
combined. No conductors besides power company conductors are allowed on the power company side
of the service equipment.

3.3.3. Dimensions
Table 3-9 and Table 3-10 shows the dimensions of different types of conduit used by MnDOT for ITS
related applications. For new underground construction, schedule 80 PVC or HDPE should be used.
Although 4-inch conduit can be used, MnDOT typically uses a maximum conduit size of 3 inches. If 3-inch
conduit is not large enough for the power or communications cables, additional 3-inch conduits may be
utilized. The standard conduit size used for power cables is 2-inch NMC. When fiber optic cable will be
used and installed by blowing the fiber through the conduit, MnDOT uses 1.5-inch NMC as the standard,
although 1.25-inch NMC may sometimes be used. For aboveground conduit connecting underground
conduit to a pole cabinet, schedule 80 PVC or RSC should be used.

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Table 3-9: Typical Conduit Dimension for Rigid Steel Conduit (RSC)
Inside
Trade Size Total Area 40% Area
Diameter
(In.) (sq. in.) (sq. in.)
(in.)
1/2 0.632 0.314 0.125
3/4 0.836 0.549 0.219
1 1.063 0.887 0.355
1-1/2 1.624 2.070 0.828
2 2.083 3.406 1.362
2-1/2 2.489 4.863 1.945
3 3.090 7.495 2.998
4 4.050 12.876 5.150
5 5.073 20.202 8.081
Table 3-10: Typical Conduit Dimension for Schedule 80 PVC and Schedule 80 HDPE (NMC)
Inside
Trade Size Total Area 40% Area
Diameter
(In.) (sq. in.) (sq. in.)
(in.)
1/2 0.526 0.217 0.087
3/4 0.722 0.409 0.164
1 0.936 0.688 0.275
1-1/2 1.476 1.710 0.684
2 1.913 2.873 1.149
2-1/2 2.290 4.117 1.647
3 2.864 6.439 2.576
4 3.786 11.252 4.501
5 4.768 17.846 7.138

3.3.4. Bridge Conduit

Whenever possible, MnDOT’s preference is to avoid installing power or communications conduit on
bridge structures. This preference is due to the additional coordination and design challenges incurred
when attaching conduit to a bridge structure. There are situations where attaching a conduit to a bridge
structure cannot be avoided. In these situations, the following detail should be referenced:
Hanger Bracket Detail:
http://www.dot.state.mn.us/rtmc/pdfdgn_design/cab/CONDUIT%20HANGER%20BRACKET_dt1.pdf
The designer needs to consider the appropriate number of expansion and deflection fittings required to
accommodate the expansion and contraction rates of both the conduit and bridge. An adequate number
of hanger brackets must be included to ensure maximum allowable conduit deflection rates are not
exceeded.

3.3.5. Boring
The designer should identify on the plans all locations where boring will be required to place the
conduit, including below roadways, ponds, slope paving, and storm sewer. All bores under roadways

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must be at a 60” minimum depth, and this depth may need to be increased to not interfere with existing
infrastructure such as storm sewer pipes or gas mains. The bore depth should be called out on the plan
sheets if this will be required at a particular location.

3.3.6. Innerduct
Innerduct is not typically used by MnDOT for ITS applications, although MnDOT does use innerduct
when installing fiber optic cables within inplace rigid steel conduits such as under railroads or on/within
bridges.

3.3.7. Pull Tape

Pull tape should be specified in the plans whenever it is to be included with the conduit installation. Pull
tape should also be included with the conduit installation when MnDOT is to install the communications
cable after contractor installation of the conduit or when the electric service provider will install the
power conductors after contractor installation of the conduit. Pull tape should be called out in the plan
as flat nylon, as rope tends to cut into non-metallic conduit.

3.3.8. Warning Tape

Warning tape shall be included with all conduit installations containing fiber optic cables, with the
exception of bored conduits, as described in Division SZ. Warning tape should be 3.15 inches (80mm)
wide, stretchable, orange in color, and bear a permanent legend that states “CAUTION: MnDOT CABLE
BELOW”.

3.3.9. Warning Markers

Installation of buried fiber optic trunk lines require that buried cable signs with an orange plastic sheath
are included in the design along the conduit route to adequately delineate the conduit path. The
designer should include the buried cable sign placement detail linked below in the plans.
Buried Cable Sign Placement Detail: http://www.dot.state.mn.us/rtmc/pdfdgn_design/fiber/New-2020-
05-19/BURIED%20CABLE%20SIGNING_dt1.pdf
Vault Protector Marker Posts (State-provided) also need to be installed at all fiber optic splice vaults and
fiber optic pull vaults at splicing locations. The Vault Protector Marker Post is shown in the “Fiber Optic
Splice Vault Installation Detail” and the “Fiber Optic Pull Vault at Splicing Locations Installation Detail.”

3.3.10. Future Needs

When designing conduit for ITS applications, the designer should consider the need to install additional
power or communications cables in the future. If future power or communications cables will likely be
needed, additional space should be provided in the conduit to accommodate these additional cables
without exceeding the maximum conduit fill ratio. If the future cables to be installed exceed the
maximum fill capacity of the conduit, a larger size conduit should be used.

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3.4. Conduit Access

3.4.1. Pull Vaults
Pull vaults are the current standard used by MnDOT and perform several important functions:
• Provide drainage for the conduit system to prevent freezing water from damaging the conduit
and/or cables
• Provide a location for bending the conduit run without damaging the cables
• Provide a junction for conduits coming from different directions
• Facilitate pulling cables over long distances
• Provide access to the system for maintenance
MnDOT has utilized a number of different types of handhole standards over the years for ITS
applications, so much of MnDOT’s existing ITS infrastructure still includes handholes. As previously
noted, pull vaults are the current MnDOT standard for all new ITS applications. The standard pull vault
installation detail is shown at the link below (each pull vault installation shall include a pull vault
extension).
Pull Vault Installation Detail: http://www.dot.state.mn.us/rtmc/pdfdgn_design/cab/NEW-2020-05-
19/PULL%20VAULT%20INSTALL_dt1.pdf
MnDOT’s standard is to splice fiber optic cables within a splice vault, but on a case-by-case basis splicing
may be approved within a pull vault. If fiber splicing is requested and approved by the RTMC to take
place in a pull vault, the standard pull vault installation detail is shown in the link below. If there is only
one fiber pigtail that needs to connect to the trunk fiber, the designer may use a pull vault with a splice
enclosure as permitted by the RTMC. If more than one fiber pigtail is needed, the designer must use a
splice vault.
Fiber Optic Pull Vault at Splicing Locations Installation Detail:
http://www.dot.state.mn.us/rtmc/pdfdgn_design/fiber/New-2020-05-
19/PULL%20VAULT%20WITH%20SPLICING_dt1.pdf
For non-fiber optic cable runs, the maximum pull vault spacing used by MnDOT is 350 feet. The designer
may use their judgment for final spacing determination. For instance, if there is a 400-foot conduit run
from the controller cabinet and a ramp meter, an intermediate pull vault could be omitted. For fiber
optic cable runs, the maximum pull vault spacing used by MnDOT is 600 feet. For lengths of fiber optic
cable over 600 feet, the cable must be blown instead of pulled. The maximum pull vault spacing used by
MnDOT for blown fiber is approximately 6,000 feet. When locating conduit runs and pull vaults, the
designer should consider the total number of conduits entering and exiting the pull vault. Whenever
possible, the designer should make sure that no more than six conduits enter/exit an individual pull
vault as it becomes increasingly challenging to maintain and reduces the likelihood the pull vault could
be used to connect a new conduit as part of a future project. Additionally, pull vaults that include fiber
splicing require a drain from the pull vault to prevent damage to the fiber and permit maintenance that
is included in the Standard Splicing Pull Vault Installation Detail discussed above. Pull vaults should not
be located in wet areas (i.e., ditch bottoms).

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3.4.2. Splice Vaults

Splice vaults are typically installed at junction points along a fiber trunk line or where ITS infrastructure
must be connected to the trunk line to route communications back to a central location. In rural areas
where there are fewer junction points and ITS devices, there is reduced need for splice vaults. In these
areas, splice vaults should be placed a maximum of approximately 6,000 feet apart. Splice vaults should
not be located in wet areas (i.e., ditch bottoms).
If there is only one fiber pigtail that needs to connect to the trunk fiber, the designer may use a pull
vault with a splice enclosure as permitted by the RTMC. If more than one fiber pigtail is needed, the
designer must use a splice vault. The standard splice vault installation detail is shown at the link below.
Standard Splice Vault Installation Detail: http://www.dot.state.mn.us/rtmc/pdfdgn_design/fiber/New-
2020-05-19/FO%20SPLICE%20VAULT%20INSTALLATION_dt1.pdf

3.5. Equipment and Service Cabinets and Shelters

3.5.1. Selection and Construction
CABINETS
MnDOT uses several different cabinet types for various applications, including the 334MP cabinet, 334Z
cabinet, 340 cabinet, pole cabinet, service cabinet, service cabinet type special, and service cabinet
240/480 with stepdown transformer. The typical applications each cabinet type is used for and the
components for each cabinet type are listed below:
• 334Z is the typical cabinet used for ramp metering and loop detectors and includes:
• 19” rack
• Type 170 controller
• Fiber optic patch panel
• Main breaker inside of cabinet (no circuit breaker enclosure, just the breaker)
• Outlet strip
• Flasher modules
• AC power surge protection
• Thermostatically controlled ventilation
• Sheath grounding units (for locating system)
• Detector card rack
• Loop detection terminal blocks wired to detector card rack
• Neoprene cabinet gasket

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Figure 3-17: 334Z Cabinet

• 334MP is the cabinet typically used for DMS control, fiber patching, and any other use where
metering or detection is not needed. These cabinets typically include:
• 19” rack
• Fiber optic patch panel
• Main breaker inside of cabinet (no circuit breaker enclosure, just the breaker)
• Outlet strip
• AC power surge protection
• Thermostatically controlled ventilation
• Sheath grounding units (for locating system)
• Neoprene cabinet gasket
• 334MP-DET is an MP cabinet upgraded with equipment necessary for vehicle detection. It is the
same as an MP with the addition of the detector card rack and terminal blocks wired to the
detector card rack.

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• 340 cabinet is a double wide cabinet with a fully functional 334Z on one side and 334MP on the
other.
• Pole cabinet is a cabinet with a short 19” rack designed for mounting on poles. A pole cabinet is
typically used on video camera or NID poles for fiber termination, transmission equipment, and
power for video camera equipment. These cabinets can be found on MNDOT’s APL.
Figure 3-18: Pole Cabinet

• Service cabinet (metered) is standard service cabinet used at ITS deployments. The service
cabinet is designed for 200A, 120/240 volt, three wire, single phase power. It also includes a
meter socket. It is constructed with 30 panel knock outs for breakers and comes with the
following breakers (unless otherwise specified):
• 1 – 60A 2-pole main breaker
• 1 – 30A 1-pole breaker
• 4 – 15A 1-pole breakers
There are times when different breakers are required for a particular ITS deployment. It is the
designer’s responsibility to identify any changes on the plans from the standard breaker
configuration that is normally provided per MnDOT’s APL specification.

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Figure 3-19: Service Cabinet

• Service cabinet type special (non-metered) – is identical to a service cabinet (metered) with the
exception of not including a meter socket. It is the designer’s responsibility to identify any
changes on the plans from the standard breaker configuration that is normally provided per
MnDOT’s APL specification.
Figure 3-20: Service Cabinet Type Special

• The service cabinet 240/480 with stepdown transformer may be used outside of Metro District if
that District prefers to share one meter and source of power for lighting and TMS.

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Figure 3-21: Service Cabinet 240/480 with Stepdown Transformer

CLIMATE-CONTROLLED SHELTERS
MnDOT uses climate-controlled shelters at critical backbone communications locations and junction
points. These shelters often include critical communications hardware that is not field hardened and
thus must be installed in a climate-controlled environment. These shelters may include a backup power
source or generator as a result of the critical communications infrastructure they support. The two sizes
of shelter that MnDOT currently uses are 10’x12’ and 12’x18’, with the size of shelter chosen for a given
location depending on how many system connections need to be made. Generally, more space is
needed in an urban area such as at a system interchange.
ENVIRONMENTAL HARDENING
Most MnDOT equipment and service cabinets are not climate-controlled and are often susceptible to
extreme temperature and weather conditions. As a result, all equipment installed in the cabinets must
be field hardened to withstand these temperature and weather extremes. Examples of field equipment
that must be hardened to perform during these extremes include Ethernet switches, surge suppressors,
and communications converters.

3.6. Additional Supporting Infrastructure

Proposed ITS devices often require that additional infrastructure be installed to support the ITS device.
This infrastructure may include the design for various structural components required to mount or
support the device, poles, foundations, attenuators, barriers, and/or guardrail installations. The
following subsections provide additional details for the design of supporting infrastructure associated
with ITS applications.

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3.6.1. Posts and Poles

When a proposed DMS will be installed on a sign bridge, the design may include either a new sign bridge
or the modification of an existing sign bridge. If modifying an existing sign bridge, a structural analysis
and design will be required, and the designer will need to coordinate with the MnDOT signing and
bridge groups to incorporate all necessary structural components. If installing a new sign bridge, the
designer will need to coordinate with MnDOT Signing and consult the MnDOT Standard Plan Sheets 700
Series for design of the sign bridge.
For all structural steel components, the designer must take fabrication lead times into consideration.
Typical structural steel lead times vary but may exceed 26 weeks. If a project is on an accelerated
schedule, the designer should consider whether MnDOT should furnish the structural steel components
independently and provide them to the contractor for installation.
The designer will also need to consider whether a Federal Aviation Administration (FAA) airspace review
(FAA Form 7460-1 Notice of Proposed Construction or Alteration) filing will need to be completed for
proposed ITS structures. The requirements for filing with the FAA for proposed structures vary based on
a number of factors including height, proximity to an airport, location, and frequencies emitted from the
structure. The FAA provides a Notice Criteria Tool that may be utilized by the designer to receive a
preliminary determination from the FAA as to whether an FAA airspace review is required for the
proposed structure. See the following link:
https://oeaaa.faa.gov/oeaaa/external/gisTools/gisAction.jsp?action=showNoNoticeRequiredToolForm
The airspace review submittal to the FAA should be filed with adequate lead time prior to the final
submittal date. It is desirable to obtain preliminary determinations from the FAA as soon as device
locations are determined. The designer is required to have an account set up with the FAA airspace
review website in order to file with the FAA and is also required to input relevant client/sponsor contact
information into the airspace review database. One can register as a new user and manage air space
review cases through the FAA website at the following link:
https://oeaaa.faa.gov/oeaaa/external/userMgmt/permissionAction.jsp?action=showLoginForm
Depending on the specific situation, it may also be warranted for a separate FAA airspace review to be
filed for construction equipment that will be utilized to install the proposed permanent structure.

3.6.2. Foundations
Most new ITS device installations will require a foundation to be installed for the pole or sign structure
that the ITS device will be mounted on. The designer will need to consider whether a standard MnDOT
foundation design will be adequate for the particular ITS application or if a special design is required.
For a new DMS sign bridge, there are two standard footing design types, a spread footing and a shaft
footing. When the DMS and sign bridge installation is part of a roadway reconstruction project, a spread
footing is typically used. If the DMS and sign bridge installation is over an existing roadway, a shaft
footing is typically used. All new sign bridges will require that a soil boring be performed at each
foundation location to determine whether the standard design is adequate. Poles required for NID and
video cameras typically utilize a standard foundation and do not require a soil boring. In areas with
unique or poor-quality soil conditions, a special foundation design may be required.

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During construction it is important that the required compaction levels be achieved as required by
MnDOT Standards Specifications for Construction and any Special Provisions.
Figure 3-22: NID Pole

3.6.3. Guardrails
When a new sign bridge is required for a DMS installation, guardrail will be required to protect the
structure from one or both directions. In rural areas, a plate beam guardrail installation may be used
and is typically covered by Standard MnDOT Plan Sheets. In urban areas, a special installation with
concrete barrier and impact attenuator are required along with a paved maintenance pull-off on the
outside shoulder. If there is a vegetated median, the plate beam guardrail installation is used. In
locations where a median barrier is present, the sign bridge is typically mounted on the structural
barrier foundation. When a special installation is required, ITS cabinets and pull vaults are placed
directly behind the concrete barrier. In rural areas, ITS cabinets should be placed outside of the clear
zone or protected by a guardrail installation.

3.6.4. Pull Off Areas and Grading

There are a variety of situations where roadway design and related quantities need to be provided in the
plans. A few examples include:

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• Filling in an area to provide an elevated location for a cabinet pad so it does not end up in a wet
area
• Creating a level work area so a ladder can be safely used by workers to service the ITS devices
• Pull-off area that is level and located farther away from the active traffic lanes to provide a safer
area to park work vehicles including bucket trucks
• A four-foot wide perimeter of Type 9 Mulch around splice vaults, poles, cabinets, and shelters
should be considered in areas that do not have established lawn (mowed approximately
weekly).
• Erosion control measures need to be considered when work is adjacent to rivers, wetlands, and
other environmentally sensitive areas. Depending on the level of impacts, the plans may require
a SWPPP and erosion control details.
The designer needs to include the appropriate pay items and quantities in the plans to allow for these
features to be constructed when required.

3.7. ITS Device Design

3.7.1. Vehicle Detection
INTRODUCTION AND USAGE
Vehicle detection is a critical component of an effective traffic management program. MnDOT uses real-
time and historic data from vehicle detection devices for a number of different traffic applications. The
two primary uses of real-time vehicle detection data by MnDOT are traffic responsive ramp meter
operations and the calculation of travel times. Ramp meters running traffic responsive operations utilize
density data from the mainline and ramp to control the rate of vehicles released by the ramp meter.
Higher downstream mainline volumes will result in a decreased vehicle release rate and, conversely,
lower downstream ramp volumes will result in higher vehicle release rates. When ramp meter volumes
become high enough to create a queue that extends to the adjacent arterial, the ramp meter is
programmed to increase its release rate.
A number of ITS systems used by MnDOT, including MnDOT’s IRIS ATMS software, rely on real-time
traffic data from vehicle detection devices. These systems process vehicle data and use it to display
vehicle speeds and congestion areas along instrumented roadway segments. Speed data from multiple
detection sites can be aggregated to calculate travel times along a particular corridor. These travel times
can then be displayed on DMS or on the Minnesota 511 Travel Information website and mobile
application. Third-party probe-based vehicle speed data can also be used to calculate travel times, but
this data is typically delayed by one to two minutes on average and thus not as reliable as real-time
speed data from vehicle detection devices.
Vehicle speed data can be used by MnDOT personnel to help locate incidents or potential problem
areas. Over time, vehicle detection data can be used to develop and track performance metrics and
overall transportation system performance. MnDOT also uses vehicle detection to assist with tolling
enforcement. MnDOT’s Truck Rollover Warning System (TROWS) uses individual vehicle speed and
classification information, in conjunction with other data inputs, to alert drivers that they are traveling
too fast for an upcoming curve. MnDOT’s truck parking information management system utilizes vehicle
detection to provide truck parking space availability at various parking facilities.

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MnDOT also archives volume and speed data from vehicle detection devices. This historic data can be
used to complete traffic studies and reports and is used in the planning processes for future roadway
improvements. This data is also used for transportation research, transportation data and analytics
(TDA), and traffic modeling.
DETECTION TYPES
MnDOT utilizes several different types of vehicle detection technologies as part of currently deployed
traffic detection systems and/or new detection deployments, including:
• Intrusive detection (in-roadway)
• Inductive loops
• Magnetometers
• Non-intrusive detection (above or on side of roadway)
• Microwave radar
• Ultrasonic
Table 3-12 includes a description of the strengths, weaknesses, and capability of several detection types.
Inductive Loop Detection
One of the more common types of vehicle detection currently used by MnDOT is inductive loop
detection. An inductive loop is an insulated wire, comprised of four wire turns per loop, imbedded in the
roadway surface. The inductive loop is installed via sawcut or an NMC installed in/under the pavement
that is connected to a loop amplifier card located in a nearby ITS cabinet. The wire loop carries a small
oscillating DC electrical current operating at a specific frequency. When a vehicle passes over or stops
above the loop, the conductive metal from the vehicle creates a reduction in the overall inductance of
the loop. The decrease in inductance results in a corresponding decrease in electrical impedance and
increase in electric current in the wire loop. The change in electric current, or percent change when
using older inductive loop technology, actuates the loop amplifier card output relay. The traffic
controller monitors the output relay 60 times per second to sense passage or presence of a vehicle. The
total number of milliseconds it is occupied is then used to derive vehicle speed.
Magnetometer Detection
Another type of vehicle detection used by MnDOT is magnetometer-based vehicle detection.
Magnetometer-based vehicle detection detects the presence and/or movement of ferrous metal
included in a vehicle by measuring changes in the earth’s magnetic field in one or more directions (x-, y-,
and z-axis) produced by that vehicle. Magnetometers can be connected to an electronics unit in an ITS
cabinet via wired or wireless communications. MnDOT uses magnetometer-based vehicle detection for
the truck parking system. Vehicles that utilize aluminum or other non-ferrous materials may not be
detected by a magnetometer.
Microwave Radar Detection
The other predominant type of vehicle detection used by MnDOT is microwave vehicle detection. A
microwave vehicle detector transmits microwave energy across an area of roadway and when a vehicle
travels through that detection beam, a portion of the transmitted microwaves are reflected off the
vehicle and back to the detector. The detector receives the reflected microwaves and detects the
presence of a vehicle. Two commonly used types of microwave radar detection are continuous wave

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(CW) radar and frequency modulated continuous wave (FMCW) radar. CW radar detectors transmit a
continuous beam of microwaves at a constant frequency and FMCW radar detectors transmit
microwaves at a constantly changing frequency.
MnDOT currently utilizes side-fire FMCW microwave vehicle detection to detect vehicles traveling along
freeway mainlines. These detectors utilize dual radar beams that are transmitted from the same
detector. The dual radars act as a virtual detection zone and can detect when the vehicle enters the
detection zone (penetrates the first beam) and when the vehicle leaves the zone (penetrates the second
beam). By comparing the time between entry and exit, along with the length of the detection zone, the
detector is able to determine an accurate measure of vehicle speed and classification. The detector is
also able to determine the vehicle’s direction depending on which of the two beams is penetrated first.
Figure 3-23: NID

MnDOT currently has a contract to use Wavetronix detection. The minimum, recommended, and
maximum detector mounting heights are listed in Table 3-11 below. MnDOT typically mounts the
detector between the recommended and maximum height. The mounting height for the detector is
based on height above the pavement surface at the nearest edge of the first detection lane. If the
ground is not level with the pavement surface, the height of the pole will be different than the detector
mounting height. The designer must obtain a cross section to determine the proposed detection pole
location. Figure 3-23 below illustrates an example cross section for determining pole placement and
height.

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Table 3-11: Wavetronix Mounting Height

Offset from first Recommended Minimum Mounting Maximum Mounting
Detection Lane (ft) Mounting Height (ft) Height (ft) Height (ft)
6 12 9 19
7 12 9 19
8 12 9 20
9 12 9 21
10 12 9 22
11 12 9 23
12 13 10 24
13 13 11 25
14 14 11 26
15 15 12 26
16 15 12 27
17 16 13 28
18 17 14 29
19 17 14 30
20 18 15 30
21 19 15 31
22 20 16 31
23 22 16 32
24 24 16 33
25 26 17 33
26 26 17 34
27 27 18 35
28 27 18 35
29 27 18 36
30 29 19 37
31 29 19 37
32 29 19 38
33 30 19 39
34 30 19 39
35 30 20 40
36 30 20 41
37 31 20 41
38 31 21 42
39 33 21 43
40 33 22 43
41 34 22 44
42 34 22 44
43 35 22 45
44 35 23 46
45 36 23 46
46 36 23 47
47 36 24 48
48 38 24 48

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Offset from first Recommended Minimum Mounting Maximum Mounting

Detection Lane (ft) Mounting Height (ft) Height (ft) Height (ft)
49 38 24 49
50-200 39 25 Must be < offset

Figure 3-24: Detector Folding Pole Placement and Height

Table 3-12: Detector Technology Strengths and Weaknesses

Technology Strengths Weaknesses Capability
Inductive loop • Flexible design that • Installation requires • Inductive loops are
satisfies a variety of pavement cut if capable of
applications doing a retrofit detecting volume,
• Mature, well project presence,
understood • Installation may occupancy, speed,
technology decrease pavement headway, and gap
• Large experience life • Some high
base • Installation and frequency inductive
• Provides basic maintenance loops are capable of
traffic parameters require a lane detecting vehicle
• Insensitive to closure classification
inclement weather • Wire loops are
such as snow, rain, subject to traffic
and fog

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Technology Strengths Weaknesses Capability

• Provides best and temperature
accuracy for count stresses
data • One loop is needed
• Common standard per lane, which will
for obtaining require multiple
accurate occupancy loops at locations
measurements with more than one
• Low cost for single lane in each
detection area direction
• Detection accuracy
may decrease when
design requires
detecting many
vehicle classes
Wireless (in- • Less susceptible • Battery powered • Magnetometer-
pavement) than loops to and thus will based detection is
magnetometer stresses caused by eventually run out capable of
(used for truck parking traffic of power and detecting volume,
applications) • Insensitive to require presence, speed,
inclement weather replacement headway, and gap
such as snow, rain, • Wireless • Multiple
and fog communications magnetometer
are susceptible to detectors can be
signal blockage used to obtain
• Installation requires vehicle
drilling hole in classification
pavement and
sealing with epoxy
Wired (in-conduit) • Less susceptible • When conduit is • Magnetometer-
magnetometer than loops to installed in based detection is
stresses caused by pavement, it can capable of
traffic decrease overall detecting volume,
• Insensitive to pavement life presence, speed,
inclement weather expectancy headway, and gap
such as snow, rain, • Installation requires • Multiple
and fog boring conduit and magnetometer
sliding through the detectors can be
detector and cable used to obtain
vehicle
classification
Microwave radar • Typically, • Susceptible to • Microwave radar is
insensitive to vehicle occlusion capable of
inclement weather • Higher cost detecting volume,
at the relatively speed, headway,
short ranges gap, and vehicle
encountered in classification (based

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Technology Strengths Weaknesses Capability

traffic management on an average
applications length)
• Direct
measurement of
speed
• Multiple lane
operation available
Passive infrared (only • Multizone passive • Passive sensor may • Infrared sensors are
used by MnDOT in sensors measure have reduced capable of
detectors that speed vehicle sensitivity in detecting volume,
combine multiple heavy rain, snow speed, headway,
detection and dense fog gap, and vehicle
technologies) • Some models are classification (based
not recommended on length)
for presence
detection
Ultrasonic (only used • Multiple lane • Environmental • Ultrasonic sensors
by MnDOT in detectors operation available conditions such as are capable of
that combine multiple • Capable of over- temperature detecting volume,
detection height vehicle change and presence, and
technologies) detection extreme air occupancy
turbulence can
affect performance
• Large pulse
repetition periods
may degrade
occupancy
measurement
Source: FHWA Traffic Detector Handbook
DETECTORS USING MULTIPLE DETECTION TECHNOLOGIES
A number of vehicle detectors utilize multiple different types of detection technology. By combining
multiple different types of detection technology, an individual vehicle detector can take the place of
multiple detectors and can be used to overcome weaknesses of an individual detection technology. The
TDC3 detector from ADEC Technologies is an example of a vehicle detector that uses multiple types of
detection technology. The TDC3 detector utilizes Doppler radar, ultrasonic, and passive infrared
detection technologies to provide a comprehensive set of vehicle data.
VEHICLE CLASSIFICATION
Many of the different types of vehicle detection technologies are capable of measuring vehicle
classification including inductive loops, magnetometers, microwave radar, and passive infrared. The
most common type of vehicle classification is based on vehicle axles. Axle-based classification often
includes both the number of axles per vehicle as well as axle spacing for each vehicle. The FHWA has
defined 13 vehicle classes based on axle configurations, which are identified in Table 3-13. MnDOT
typically utilizes vehicle detection to determine speed, volume, and occupancy, but does not typically

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determine vehicle classification. Although the RTMC seldom uses vehicle classification data, this data
can be provided to other groups that need this data.
Table 3-13: FHWA Vehicle Classification
Class # Axles Vehicle Description Notes
1 2 Motorcycles
2 2 Passenger vehicles Sedans, coupes, and station
wagons
3 2 Other 2-axle, 4-tire single unit vehicles Includes pickups, vans, campers
4 2 or more Buses Includes only traditional buses
5 2 2-axle, 6-tire, single unit trucks
6 3 3-axle single unit trucks
7 4 or more 4-axle single unit trucks
8 3,4 4 or fewer axle single-trailer trucks Semi with trailer
9 5 5-axle single-trailer trucks
10 6 or more 6 or more axle single-trailer trucks
11 4,5 5 or fewer axle multi-trailer trucks
12 6 6-axle multi-trailer trucks
13 7 or more 7 or more axle twin trailer semi-trucks
COMPONENTS
Typical components required for a vehicle detector are identified in Table 3-14 along with the
corresponding section of this design manual that should be referenced for additional design information
related to that component.
Table 3-14: Detection Components

Component Manual Locations

Loop Detector This section
NID This section
NID Pole This section
Control Cabinet Section 3.5
Power Section 3.1
Communications Section 3.2
GENERAL DESIGN CONSIDERATIONS
When selecting the type of detection and detection location that will be utilized for a project, several
factors should be considered. A list of general design considerations is included below.
1) Does the detector meet the “needs” outlined in the project Concept of Operations, Regional
Operations Plan, and/or MnDOT statewide ITS architecture?
2) Can the detector accurately detect all desired vehicle data required for the project (i.e., vehicle
volume, speed, occupancy, and/or classification)?
3) Does the detector satisfy the precision, spacing, and accessibility requirements for the project?
4) Is the detector able to function during all times of the year, all times of the day, and all weather
conditions?

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5) Does the detector minimize the amount of new infrastructure needed and allow for devices to
be collocated where possible?
6) When in-pavement detection will be used, is the pavement condition of sufficient quality to
support operation of the detection for its maximum life expectancy?
7) Has the proposed detector infrastructure been evaluated for conflicts with other existing or
proposed infrastructure such as bridges, signs, or drainage elements?
8) Has the detector site been chosen so that it will minimize maintenance costs and safety
concerns (e.g., is there sufficient space to park a bucket truck without the need for a full lane
closure and significant traffic control)?
9) The index numbers of existing detectors can be found on the All Detector Report
(http://data.dot.state.mn.us/datatools/)
10) The numbering system comes from a database from the RTMC operations group. Number from
right to left. N1, N2, etc. and the letter represents the direction of traffic flow (e.g. N means
northbound).
11) Loop detector sizes for mainline lane detection are typically 6 feet by 6 feet for a 12-foot lane
and are centered in the lane. Loop detectors located on ramps are 6-feet long, but the width
varies. The width of these loops is the ramp roadway width, not including any shoulder, minus 6
feet (i.e. 2 * 3 feet from the edge of pavement to each side of the ramp). Figure 3-24 shows how
the widths of the loops are determined.
Figure 3-25: Loop Detector Configuration on Entry Ramps

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Figure 3-26: Loop Detector Index Number

Figure 3-27: Loop Detector Function Designations

Mainline Detection (Microwave Radar)

1) When placing a detector, avoid placing detection in areas with a significant amount of weaving
and where traffic is slowing for merging vehicles as this can lead to erroneous counts.

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2) Mainline detectors in the Metro District are typically located every half-mile.
3) When placing a detector, consider the location of future infrastructure (e.g., future lanes,
shoulders, etc.).
4) Is the detector mounted at a height that falls within the manufacturer’s recommended range?
a. MnDOT typically mounts the detector between the recommended and maximum
height.
5) Is the detector capable of detecting all traffic lanes and is the detector far enough away (12 foot
minimum distance is required) from the closest lane but no more than 200 feet from the
farthest lane so that it can accurately detect all traffic lanes? The designer should identify the
distance from the NID to each traffic lane on the plans.
6) Is the detector mounted high enough to prevent occlusion of vehicles when adjacent to larger
vehicles?
7) Is there a high median barrier that might cause occlusion or adversely impact the detector’s
ability to function properly?
8) Is there guardrail present that might cause reflection or adversely impact the detector’s ability
to function properly?
9) Is the detector far enough away from a bridge or sign structure to prevent any negative impacts
of the bridge or sign structure? The minimum clearance is 40 feet.
10) Do the existing and/or proposed grades slope up or down such that they would prevent the
detector from accurately measuring vehicles in the farthest travel lanes?
11) If a new pole is required for the detector, is the pole located beyond the clear zone or protected
by a suitable safety barrier?
12) Is another detector located on the opposite side of the roadway and, if so, is there sufficient
offset in placement to avoid interference with one another? The minimum offset is 70 feet.
13) If buses will be utilizing the shoulder, the detector should be located such that it is capable of
detecting traffic on the shoulder.
Ramp Detection (Inductive Loops)
1) When installing a loop detector in existing pavement, check the pavement condition and avoid
areas where the pavement is damaged.
2) When installing a loop detector in new concrete pavement, the loop detector should be placed a
minimum of 3 feet from dowel baskets at pavement joints. Do not place the loop detector
above a culvert, where there would likely be supplemental pavement reinforcement.
3) When a porkchop is present at the upstream end of the ramp, the location of the queue
detection loop(s) may need to be adjusted to capture both traffic movements or two loops may
be needed.
4) When locating a passage loop detector, place the loop at least 25’ beyond the ramp meter.
5) When a HOV bypass lane is provided, a passage loop detector should also be provided for the
HOV bypass lane in addition to the passage loop detector beyond the ramp meter.
6) Naming of loops is very important, consult with the MnDOT RTMC operations group for loop
naming.
VEHICLE DETECTION DESIGN PROCESS
General design steps for all ITS devices are listed in Section 4.7 and detailed design steps for vehicle
detection are listed in Section 4.8.1.

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3.7.2. Video Cameras

INTRODUCTION AND USAGE
Video cameras are one of the primary tools used by MnDOT to remotely monitor real-time traffic
conditions across the State’s transportation system and make informed traffic management decisions.
MnDOT traffic operations and maintenance personnel located at the RTMC or other State facilities can
use this video to identify congestion, incidents, and/or other potential issues and implement traffic
management strategies designed to reduce their impacts and improve safety and mobility. Most MnDOT
video cameras have pan-tilt-zoom (PTZ) capabilities that allow an operator to remotely position the
camera to obtain the best possible visual of the area of concern. The State Patrol are also located in the
RTMC and use video to enhance incident response. This video provides the situational awareness
needed to deploy the appropriate emergency response and clearance vehicles to the scene. Video
allows MnDOT to cooperatively work with incident response personnel to quickly resolve the issue and
restore normal traffic operations along the corridor. MnDOT and the State Patrol utilize video cameras
to:
• Monitor real-time traffic conditions
• Manage traffic and congestion
• Locate and/or verify traffic incidents and disabled vehicles
• Improve incident management and response
• Verify messages posted on Dynamic Message Signs (DMS)
• Observe and/or verify local weather conditions and hazards
• Dispatch safety, operations, or maintenance personnel
• Monitor work zone operations and temporary traffic control
Figure 3-28: Video Camera

MnDOT also shares snapshots and video from these camera video feeds with the public through the
Minnesota 511 Traveler Information System. Travelers can utilize these video snapshots and video to

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obtain current traffic conditions and identify potential congestion or incidents along their planned travel
route.
COMPONENTS
Typical video camera components are identified in Table 3-15 along with the section of this design
manual to reference for additional information on that component. Video camera warrants are
discussed in Section 2.4.3.
Table 3-15: Video Camera Components
Component Manual Location
Video Camera This Section
Mounting Hardware This Section
Pole Cabinet Section 3.5
Power Section 3.1
Communications Section 3.2
VIDEO CAMERA
MnDOT has deployed several different types and styles of video cameras over the years and not all
cameras rely on the same technology, features, and functionality. The type of video camera is largely
dependent on when it was deployed, its intended use, and the constraints of the location in which it was
installed. The following includes a brief overview of the types and styles of video cameras currently used
by MnDOT. MnDOT utilizes digital cameras where the digital video encoder hardware and/or software
CODECS are integrated directly into the video camera unit and no additional hardware is required in the
field cabinet. MnDOT’s standard for all new video cameras in use is high-definition (HD); however, there
are still many standard-definition (SD) cameras deployed across the State. MnDOT is in the process of
upgrading all SD cameras to HD, but the process will take time. As SD cameras fail, they will be replaced
with HD cameras. The camera housing is made up of the environmental enclosure and PTZ unit, heaters,
wipers, etc. MnDOT typically uses barrel style cameras. Barrel cameras were traditionally used in fixed
locations but have seen many advancements in recent years and now provide PTZ capabilities and are
used extensively by MnDOT. Dome cameras previously were used but due to icing challenges and a blind
spot with the domes due to the mounting, they are typically not used by MnDOT. There are some other
cameras used by MnDOT for specific applications such as truck parking and gate arm monitoring.
Video cameras can be fixed or controlled. Fixed video cameras are stationary and cannot be remotely
repositioned. Repositioning a fixed video camera requires physically repositioning the camera in the
field. These cameras are often deployed for security purposes, focus on a particular area of interest, and
typically provide zoom-in/zoom-out and focus functionality.
Controlled video cameras, often referred to as PTZ cameras, allow users to remotely reposition the
camera to view a particular area of interest. Freeway video cameras deployed by MnDOT are PTZ
cameras.
FIELD OF VIEW
Current video camera technology allows for camera spacing of up to 2 miles and a field of view of 1-2
miles in each direction if the camera mounting, topography, road configuration, and weather are ideal.
The location for video cameras is dependent on the terrain, number of horizontal and vertical curves,

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desire to monitor weaving areas, identification of high-incident locations, and the need to view ramps
and arterial streets. Each prospective site must be investigated to establish the camera range and field-
of-view that will be obtained as a function of mounting height and lens selection.
PERFORMANCE BANDWIDTH
It is an issue if there is not a high bandwidth connection to the camera. For example, in some remote
rural areas the camera may be using a wireless link with much less bandwidth than a fiber optic
connection. In cases of limited bandwidth, there are trade-offs related to camera resolution, refresh
rate, and compression losses. The communication system needs to be designed to effectively allow
access to the video and minimize bottleneck links. Performance also affects camera control. In a low
bandwidth situation, there is a delay between issuing the camera movement command and when the
camera moves, which makes it difficult to point the camera where desired in real-time. In these
situations, it is helpful if the camera control includes the ability to use presets so that the operator can
easily point the camera in the desired direction.
VIDEO CAMERA MOUNTING OPTIONS
For fixed location video camera systems, video cameras are permanently mounted either on existing
structures along the freeway or on specially installed camera poles.
FOLDING POLE
MnDOT video cameras are typically mounted on a 50-foot high video camera folding pole. See below for
the typical video camera folding pole detail. NID folding poles, which have varying heights, are also used
to mount video cameras. Additional and current details can be found on the approved/qualified product
list (APL/QPL) at http://www.dot.state.mn.us/products/. Folding poles allow for installation and
maintenance without the need for bucket trucks, ladders, etc.
Video Camera Pole Installation Detail:
http://www.dot.state.mn.us/rtmc/pdfdgn_design/cam/CCTV%20POLE%20INSTALLATION_dt1.pdf

Figure 3-28 below illustrates the swing path of the 50’ video camera folding pole. The designer must
consider this when determining the locations of poles, cabinets, etc. and their proximity to trees and
other obstacles to ensure that the swing path of the pole is not obstructed.

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Figure 3-29: 50’ Video Camera Folding Pole Swing Path

EXISTING STRUCTURES
If the video camera is to be mounted on an existing structure, coordination with the appropriate MnDOT
functional group is required. For instance, cameras mounted on a bridge require coordination with the
bridge group.
TRAFFIC SIGNAL INSTALLATION
A video camera system may be included at a traffic signal or arterial management system. For these
systems, coordinate with the traffic signal owner to determine the correct quadrant(s) to locate the
camera. These are often installed on a specially designed mounting pole that takes the place of one of
the signal luminaire davit arms.
VIDEO CAMERA DESIGN CONSIDERATIONS
This section includes high-level design considerations and guidance to assist ITS practitioners engaged in
video camera design for MnDOT. The sections below include several questions designers should seek to
answer as they begin the video camera system design process.
Location/Placement Guidelines
• Has the camera location been chosen/designed with consideration to maximizing visibility?

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• Has the pole location been designed with consideration to the swing path of the folding pole?
• Has a site for the camera been chosen that considers the available utilities and the
cost/constraints associated with connection to those utilities?
• Has the site been chosen with consideration to protecting the camera structure and ensuring
that it will last without undue maintenance necessary to the structure and the surrounding site?
• Has a site been chosen that makes the best use of the operational needs of a video camera
system (e.g., incident management)?
• Has a site been chosen that satisfies safety requirements for personnel performing maintenance
on the system?
• Has the site been selected so that it will minimize maintenance costs (e.g., there is sufficient
shoulder to park a bucket truck without the need for a full lane closure to perform maintenance
activities)?
• Is the structure the video camera is mounted on located beyond the clear zone or protected by
a suitable safety barrier?
• Has the site been chosen considering safety and conditions so that access will be available year-
round, in all weather conditions, and at all times of the day?
• Has the availability of communications infrastructure been evaluated? If a wireless link must be
used, tradeoffs will need to be made regarding camera resolution, refresh rate, and
compression losses.
Video Camera Type
• What application is the video camera being used for? Different cameras are used for more
specific applications such as truck parking and gate monitoring.
Camera Mount
• Will the camera be mounted on a standard folding pole, existing structure, or traffic signal pole?
If mounted on an existing structure or traffic signal pole, coordination with other functional
groups will be required.
Control Cabinet
• The new standard is to include a pole cabinet on all video camera and NID poles for future
proofing purposes, as CAV-X applications may eventually utilize them.
Procurement
• Which components are State-provided, and which are to be provided by the contractor? MnDOT
has a multi-year contract for the procurement of video cameras. Video cameras, 334 style
control cabinets, and communication cables (between the Ethernet switch and video camera),
as well as Ethernet switches, are typically furnished and installed by the State. Service cabinets,
pole cabinets, video camera and NID poles, conduit, pull vaults, and power cables are furnished
and installed by the contractor.
VIDEO CAMERA DESIGN PROCESS
General design steps for all ITS devices are listed in Section 4.7 and detailed design steps for video
cameras are listed in Section 4.8.2.

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3.7.3. Dynamic Message Signs

INTRODUCTION AND USAGE
A Dynamic Message Sign (DMS) is an electronic sign mounted adjacent to or above the roadway that is
capable of displaying multiple messages to passing motorists. Depending on its location and use, a DMS
may also be referred to as a Variable Message Sign (VMS), Changeable Message Sign (CMS), or Blank-
Out Sign (BOS). DMS messages can be changed locally but are typically managed remotely from a central
location or traffic management center (TMC). DMS have many different applications including:
• Incident management and route diversion
• Warning of adverse weather conditions
• Special event applications associated with traffic control or conditions
• Control at crossing situations
• Lane, ramp, and roadway control
• Priced or other types of managed lanes
• Travel times
• Warning situations
• Traffic regulations
• Speed control
• Destination guidance
• AMBER alerts
Figure 3-30: Dynamic Message Sign

DMS messages are typically focused on safety or transportation conditions and are comprised of three
primary components: a problem statement, a location, and a recommended action. The problem

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statement informs the motorist of a particular event or incident, the location provides general
information on the location of that event or incident, and the recommended action informs the motorist
of the action they should take. The MN MUTCD includes several additional requirements for developing
and displaying messages on a DMS.
COMPONENTS
Typical DMS components are identified in Table 3-16 along with the section of this design manual to
reference for additional information on that component.
Table 3-16: DMS Components
Component Manual Location
Dynamic Message Sign This Section
Sign Structure This Section
Control Cabinet Section 3.5
Power Section 3.1
Communications Section 3.2
DMS DESIGN CONSIDERATIONS
This section includes high-level design considerations and guidance to assist ITS practitioners engaged in
DMS design for MnDOT. The sections below include several questions designers should seek to answer
as they begin the DMS design process.
Longitudinal Placement
• Is the DMS located in the Metro District, an urban area outside of the Metro District, or a rural
area?
• Is the DMS visible and unobscured?
• Is the DMS located sufficiently upstream of any potential diversion routes?
• Is the DMS located a sufficient distance upstream or downstream of any existing guide signs?
Lateral Placement
• Is the DMS structure located outside of the clear zone or protected by a suitable safety barrier?
• Has the lateral offset of the DMS been accounted for when calculating the length of the Reading
and Decision Zone?
CAV Considerations
• Will nearby CAV roadside units (RSUs) require direct data feeds from the DMS?
• Will nearby CAV RSUs benefit from shared infrastructure required as part of the DMS
installation?
Sign Characteristics
• All new DMS are to be full matrix, full-color, and have a 20 mm pixel pitch. Prior DMS
characteristics varied based on the DMS application. It is important to note that DMS standards
may change, and designers should verify current DMS characteristics and design requirements
used by MnDOT before beginning design.
• Which DMS size is required for the application? Typical DMS sizes include 8 feet by 18 feet, 8
feet by 32 feet, and 8 feet by 42 feet. The most commonly used sizes are 8 feet by 18 feet and 8

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feet by 32 feet, but other sizes may be used in special circumstances or when dictated by
existing or proposed conditions.
Viewing Angle
• Has a sign viewing angle been chosen that complements the roadway alignment and the DMS
structure?
Sign Access
• Are there any traffic, environmental, or safety factors that warrant a specific type of sign access?
Different access types include walk-in, rear access, and front access. Walk-in DMS are preferred
for all overhead DMS as these style signs are easier to maintain and reduce the impact on traffic
operations. Front access was previously used for E-ZPass price display insets on static E-ZPass
sign panels, but these have now been replaced with full 8 foot by 18 foot DMSs.
• If walk-in DMS is used, is a left door or right door needed? This is dependent on site-specific
considerations and must be determined before DMS can be procured.
• If the DMS is ground-mounted, is there an Occupational Safety and Health Administration
(OSHA)-compliant area for the placement of a ladder for maintenance operations?
Structure
• Is the DMS overhead (roadway bridge or standard truss (full sign bridge or cantilever design) or
ground mounted?
• Have visibility, road speed/volume, right-of-way, maintenance, and cost been considered when
selecting the type of sign structure?
• Is there sufficient vertical clearance for the sign and the sign structure? The minimum low steel
clearance value is currently 16 feet 4 inches although MnDOT uses 17 feet 4 inches to the lowest
hanging device.
Procurement
• Which components are State-provided, and which are to be provided by the contractor? MnDOT
has a multi-year contract for the procurement of DMS and 334 Style Control Cabinets. DMS and
control cabinets are typically furnished by the State and installed by the contractor. Service
cabinets, conduit, pull vaults, communication cables, and power cables are typically furnished,
installed, and terminated by the contractor.
Control Cabinet
• Is the control cabinet located within a reasonable distance of the sign?
• Is the sign face visible from the control cabinet location?
LOCATION AND DESIGN
The ideal location for a permanent DMS on a controlled access roadway is in advance of an interchange
or access point in order to inform drivers in advance and provide them with sufficient time to take some
action in response to the message being displayed on the sign. A DMS should not compete with existing
roadway guide signs. At times, relocation of static signs may be required to install a DMS at a critical
location. In general, DMS should be located:
• Upstream of major decision points (e.g., exit ramps, freeway-to-freeway interchanges, or
intersection of major routes that will allow drivers to take an alternate route)

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• Upstream of bottlenecks, high-accident areas, and/or major special event facilities (e.g.,
stadiums, convention centers)
• Where regional information related to weather conditions such as snow, ice, fog, wind, or dust
is critical
The ease with which a sign can be detected in the environment (conspicuity) and the ease with which
the message can be read (legibility) will enhance the effectiveness of motorists' visibility of the DMS and
its message. In addition, the way the message is displayed must be considered (e.g., if the message is
too luminous, it can be easily detected but difficult to read because of glare). Factors that affect the
legibility of light-emitting DMS include the character height; font style; character width (spacing and size
of pixels); spacing of characters, words, and lines; size of sign borders; and contrast ratio.
The designer needs to consider the site characteristics of the area in which the DMS will be located.
Factors that should be considered include:
• The operating speed of traffic on the roadway
• The presence and design characteristics of any vertical curves that may impact sight distance
• The presence of horizontal curves and/or obstructions such as trees, bridge abutments, or
construction vehicles that constrain sight distance to the DMS around the curve
• The location of the DMS relative to the position of the sun (for daytime conditions)
• The location of any static guide signs in the vicinity
• Presence of wetlands
• Whether unusual site-specific weather conditions apply that could degrade sign visibility
Other design considerations include sign size (which affects message length and support structure
requirements), maintenance access (e.g., walk-in housings, front access), technology, viewing angle and
distance, and character size.
The maximum length of a message that will be displayed on the sign is primarily dictated by the amount
of information a driver can reliably read and comprehend during the period they are within the legibility
distance of the DMS. The maximum length of a DMS message is also controlled by the characteristics of
the sign. These include the type of sign (typically LED), the number of lines available, and the number of
characters on each line. Each of these characteristics will affect the distance at which a sign can be read
and, consequently, how much information can be presented on it. Guidance on MnDOT DMS messages
is documented in “2012 CMS Manual of Practice,” although it should be the responsibility of the TMC
manager/supervisor to assess the DMS characteristics and determine the maximum length of message
to display.
LONGITUDINAL PLACEMENT
As noted earlier, the primary considerations related to longitudinal placement of a DMS are to minimize
obstructions of and by the DMS, provide maximum visibility of the DMS message, and allow the driver
ample time in which to read, process, and react to the message. When the DMS is located near at-grade
intersections, the designer needs to ensure that the DMS does not negatively affect intersection sight
distances. Once the DMS visibility distance has been determined, the designer will need to check for
existing guide signs in the area to ensure that they will not obstruct the visibility of the DMS. DMS and
guide signs should be spaced far enough apart to allow the driver time to read and process the

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information on each sign. Typically, DMS should be located a minimum of 800 feet from an upstream or
downstream guide sign.
The approach area to a DMS can be divided into three zones as shown in Figure 3-30.
• Detection Zone
• Reading and Decision Zone
• Out-of-Vision Zone
Figure 3-31: DMS Visibility (Not to Scale)

Visibility Distance

Legibility Distance

Detection Reading and Decision Out-of-Vision

A B C D

Detection Distance = AB
Visiblity Distance = AD
Legibility Distance = BD
Reading and Decision Distance = BC
Out of Vision Distance = CD

Sign

Detection Zone
At typical (70 mph) highway speeds, the DMS should be visible to the approaching driver from between
1,000 to 2,000 feet away. The visibility distance should also be increased if the DMS is placed at an offset
from the travel lanes.
Reading and Decision Zone
As a general rule, the message panels on a highway-deployed DMS usually contain room for three lines
of text, each with 12 to 21 characters.
Drivers need approximately one second per word to read and comprehend a message. Traveling at 70
mph, this equates to roughly enough time to read and comprehend a 10-word message. The character
height, cone of vision, and lateral placement must all be considered when determining the placement of
the sign in order to meet sight distance requirements. Typically, the design needs to have drivers
recognize the sign at least 800 feet away, and drivers need to be able to comprehend the message a
minimum of 600 feet away.
Out-of-Vision Zone
Once the driver gets close to the sign, they will not be able to read the message. The out-of-vision zone
distance is determined by the viewing angle of the sign, the structure the sign is attached to, and the
lateral placement of the sign.

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LATERAL PLACEMENT
National standards regarding lateral placement of signs must be followed when locating and designing a
DMS. For overhead mounted DMS, which lane(s) the DMS is placed above depends on the application.
For express lane pricing signs, the DMS should be centered over the express lane, while a general
purpose DMS should be centered over the general-purpose lanes. Roadside DMS must be placed outside
of the clear zone or shielded with a Manual for Assessing Safety Hardware (MASH) compliant
crashworthy barrier if placed within the clear zone. The designer should use the MnDOT Road Design
Manual and the AASHTO Roadside Design Guide to determine the appropriate clear zone at the DMS
location. The DMS structure must be placed far enough behind the guardrail to comply with the
minimum guardrail clearance values. Consideration should also be made for snow being thrown by
plows, so placing the sign structure right behind the guardrail is not ideal.
The offset of the DMS (i.e., horizontal distance to the sign from the travel lanes) will require additional
sight distance to clearly view and react to the sign.
Sign Type Selection
The selection of the sign type, the configuration of the display, and the technology employed all have
direct and indirect impacts on the visibility of the message that will be displayed on the DMS. RTMC
operations staff need to be consulted to confirm the planned use of the sign and associated DMS model
and mounting location.
Matrix Characteristics
DMS display characters and symbols in a matrix format are generally designed in one of the following
three patterns:
• Character matrix (oldest)
• Line matrix (older)
• Full matrix (current)
Full matrix DMS displays are the standard format used for permanent MnDOT applications. In this
format, the entire display consists of a continuous matrix of pixels.
The industry-standard DMS matrix technology is Light-Emitting Diode (LED) signs. LEDs are
semiconductors that emit light when current is applied. Typically, several individual LEDs are "clustered"
together to create each pixel. Color displays use a red-green-blue (RGB) cluster for each pixel. LEDs have
the added benefit of being able to display signs in full color with the appropriate LED type. The reliability
of LEDs is very high.
MnDOT has a multiyear contract for the procurement of full-matrix LED-style DMS.
VIEWING ANGLE
Viewing angles are defined as the area in which the intensity of the LEDs is at 50% of their maximum
brightness when a traveler is viewing the DMS from a straight position. For example, at 15 degrees off-
center, the LED brightness in a standard 30 degree viewing cone would be 50% of the maximum
intensity. The DMS display brightness is adjusted to accommodate different ambient light conditions
(day, night, solar glare).

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Viewing angle is an important design consideration and will depend on the mounting location of the
DMS and the curvature of the roadway. MnDOT does not typically utilize DMS where the viewing angle
is less than 15 degrees (30-degree cone).
The roadside signs are skewed so they are not perpendicular to the road to maximize the legibility of the
sign. The designer needs to align the DMS so it is perpendicular to the driver’s position 500 feet from the
sign. The skew angle will vary depending on the offset from the side of the road. The skew angle
typically varies from 3-12 degrees. All DMSs mounted on standard truss sign bridges are mounted
perpendicular to the road. For DMSs mounted to roadway bridges, the acceptable skew varies from 3-10
degrees. The DMS must be mounted flat to the face of the bridge due to structural design and access
considerations, so if the bridge is skewed more than 10 degrees the DMS cannot be placed on that
bridge.
SIGN ACCESS
DMS generally utilize one of three different types of access: rear, walk-in, and front access. For overhead
or cantilever DMS, MnDOT prefers walk-in style signs in order to avoid the need for traffic control or
lane closures for maintenance and to reduce impacts on traffic operations. When installing a DMS near a
ditch or drainageway, the designer should consider the walk-in style with the door on the side to
provide the closest access to the ground. The designer will also need to consider any clearing and/or
grading required around the sign in order to provide an OSHA-compliant work area for the sign. The
designer should also consider whether there is room for a maintenance vehicle to access the site and
maintain the sign, and in some cases a vehicle pull-off is desired.
OVERHEAD VERSUS ROADSIDE MOUNTING
If there are more than two lanes per direction of traffic or heavy traffic with two lanes per direction, the
overhead mount is preferred since other traffic has less opportunity to obstruct the visibility of the DMS.
For two lane roads (one lane per direction) or for four lane roads with light traffic, a roadside mounted
DMS may be acceptable and is typically less expensive. Table 3-17 provides some pros and cons of the
various support types.
Table 3-17: DMS Support Type Comparison
Support Type Pros Cons Other Considerations
Overhead (mounted • Preferred option • Less visibility than • Can be used on any
on roadway bridge) • Better for visibility mounted on roadway type
• Lower cost than standard truss if • Utilize on high
standard sign truss bridge has a larger volume roadways
skew
Overhead (mounted • Best for visibility • Higher cost than • Alternative if limited
on standard truss) • No skew compared mounted on right-of-way
to roadway bridge roadway bridge • Can be used on any
mount roadway type
Overhead (mounted • Best for limited right- • Higher cost than • Alternative to
on cantilever – 18’ of-way situations roadside roadside if limited
DMS only) where roadside DMS right-of-way
won’t fit • Maximum span
length is 34 feet

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Support Type Pros Cons Other Considerations

Roadside • Lowest cost • Smaller display • Need adequate right-
• Worst for visibility of-way to place
• More susceptible to outside of the clear
damage during snow zone to minimize the
removal activities chance of it being hit
The minimum low steel clearance value is 16 feet 4 inches for roadway bridges per federal guidelines,
and the MnDOT standard for standard sign trusses is 17 feet 4 inches.
DMS DESIGN PROCESS
General design steps for all ITS devices are listed in Section 4.7 and detailed design steps for DMS are
listed in Section 4.8.3.

3.7.4. HOT Lanes

INTRODUCTION AND USAGE
MnDOT operates several toll lane facilities in the Minneapolis-Saint Paul Metropolitan Area, and they all
operate as High Occupancy Toll (HOT) lanes. During set times of day, transit buses, motorcycles, and
vehicles with two or more occupants (includes children of all ages) (HOV 2+) may drive in the designated
E-ZPass Express Lanes for free. Single occupant vehicles that have a E-ZPass account and toll tag must
pay a fee to drive in the E-ZPass Express Lanes during set times of day. During all other times of day, all
motorists may drive in the E-ZPass Express Lanes (with the exception of the reversible lane sections on I-
394). Overhead E-ZPass signs will read “OPEN TO ALL TRAFFIC” when the lanes are open to all motorists.
The fees to drive in the E-ZPass lanes during peak-travel times range between $0.25 and $8. Having
variable pricing helps keep traffic in the E-ZPass lanes flowing between 45 mph and the posted speed
limit during peak-travel times. Pricing is dependent on the speeds in the E-ZPass lane only and does not
consider the general-purpose lanes. The DMS Pricing Sign is updated every three minutes and changes
depending on the current demand and speeds in the E-ZPass lane.
The purpose of these projects is to improve travel times and reduce congestion for users along the
highway, and to provide an uncongested express lane for transit buses, motorcycles, high-occupancy
vehicles (HOV 2+), and single-occupancy vehicles paying an electronic toll. Drivers that use the HOT
lanes will experience improved traffic flow, reduced congestion, and better commute times along the
route.
COMPONENTS
Typical components required for a HOT lane project are shown in Table 3-18 along with a reference to
the section of this manual discussing the component.
Table 3-18: HOT Lane Components
Component Discussion
Toll Reader (RSU) This Section
Tolling Antenna This Section
Enforcement Beacon System This Section
DMS Pricing Sign This Section

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Component Discussion
Overhead Structures This Section
Control Cabinet Section 3.5
Power Section 3.1
Communications Section 3.2
TOLL READER
The toll reader is located in the controller cabinet and requires Ethernet communications. The toll
reader is also referred to as a roadside unit (RSU). This RSU is not the same as the RSU used in
connected vehicle applications. Every location with a toll reader is technically a toll plaza. The E-ZPass
tag information is sent via a signal that is obtained by the tolling antenna and sent to the toll reader that
records the tag ID. The E-ZPass toll collection system detects and processes E-ZPass tags, which are then
provided to IRIS for further processing. IRIS utilizes tag IDs from the toll collection system to track
traveling vehicles to determine the length of the trip and ultimately the price that is charged to the
customer’s prepaid account.
TOLLING ANTENNA PLACEMENT
Tolling antenna placement is largely driven by the placement of the DMS pricing signs and regulatory E-
ZPass signs shown in Figure 3-34 and Figure 3-35. The preferred placement of the tolling antenna is
below the regulatory sign directly after the second DMS pricing sign at the beginning of the lane, but this
may not always be possible due to site-specific constraints. If it cannot be placed below the regulatory
sign, it should be placed below the second DMS pricing sign. After the first tolling antenna location,
additional tolling antenna placement is largely determined by interchange entrance ramp locations
where vehicles may enter the E-ZPass lane. This gives the driver time to decide whether they want to
enter/stay in the HOT lane before reaching the tolling antenna and being charged a fee. The mounting
height and angle (15 degrees) of the tolling antenna are also important for optimal operations. Tolling
antenna overhead sign truss and bridge mounting details are provided in Figure 3-31 and Figure 3-32,
respectively. If the tolling antenna is not placed correctly, the antenna could read toll tags in the
adjacent general-purpose lane. It is also important to note that the tolling antenna is directional, so for a
reversible lane facility, such as the I-394 E-ZPass reversible lane section, there must be separate tolling
antennas mounted for each direction of operation.

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Figure 3-32: Tolling Antenna Overhead Sign Truss Mounting Detail

Figure 3-33: Tolling Antenna Bridge Mounting Detail

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Figure 3-34: Tolling Antenna Pipe Mounting Detail

ENFORCEMENT BEACON SYSTEM PLACEMENT

The enforcement zone should be placed where there is adequate roadway width to be able to have a
wide shoulder adjacent to the HOT lane for a State Patrol officer to park where the officer is able to view
the enforcement beacon and the vehicle committing the violation. The preferred left shoulder width to
provide an enforcement shoulder is 10 feet. It is striped the same as a regular left shoulder, so the only
difference is the additional pavement width. A 10-foot continuous inside shoulder is preferred in both
directions, but if this is not possible the inside shoulder width can be alternated to provide intermittent
enforcement shoulders in each direction. The officer uses the enforcement beacon while parked and
while driving. The enforcement beacon must be placed at the same location as the tolling antenna. The
enforcement device consists of an ADEC TDC3 detector and a beacon that displays different colors based
on whether it successfully read a toll tag via the toll reader. When the ADEC TDC3 detector detects a
vehicle in the HOT lane, it sends a signal to obtain a read from the tolling antenna, which then attempts
to read a toll tag via the toll reader. Depending on whether the toll reader registers a valid read, the toll
reader then sends via a contact closure a signal to the two enforcement light colors. The enforcement
beacon displays a blue light for a valid read and an amber light for an invalid read. Locations for
enforcement need to be considered during the design, and areas of adequate width need to be provided
to:
1. Allow the State Patrol to pull over violators in an area that will not result in the HOT lane being
blocked
2. Provide a pull-off at strategic locations where State Patrol can park and observe vehicles and the
enforcement beacon simultaneously
DMS PRICING SIGN PLACEMENT
DMS pricing sign placement is based on Figure 3-34 and Figure 3-35. There are typically two DMS pricing
signs toward the beginning of the HOT lane. The first DMS pricing sign should be placed between ¼ and
½ mile prior to the start of and at intermediate openings in the HOT lane. For intermediate openings, it
should be placed approximately 2,000 feet after the major entrance ramp. Formal collaboration

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between the RTMC and the signing group is required for HOT lane design since signing is a major
component of the design.
OVERHEAD STRUCTURES (SIGN BRIDGE OR ROADWAY BRIDGE)
DMS pricing signs, tolling antennas, enforcement beacons, and regulatory E-ZPass signs are all mounted
above the HOT lane on sign bridges or roadway bridges. For each device, requirements for the sign
bridge design vary as listed below:
• All sign bridges require sign post nipples to accommodate cables for ITS devices
• Walkways must be included for DMS pricing signs, but they are not included if there is only a
tolling antenna mounted to the structure
For devices to be placed on roadway bridges, the roadway bridge location should be close enough to
adhere to all the placement guidelines in this section.
CONTROL CABINET PLACEMENT
Once the toll reader and DMS pricing sign placement has been determined, the placement of the
controller cabinets can be established. This placement involves many factors, including:
• Distance between the controller cabinet and the tolling antenna
• Safety of the cabinet location
• Grades
• Drainage
• Maintenance accessibility (parking availability for maintenance vehicles)
A 334MP style cabinet is used at tolling antenna and DMS pricing sign locations. The distance between
the controller cabinet and equipment is of concern since the toll reader communication cable has
distance and bending radius constraints. All cabinets for a HOT lane facility utilize an urban concrete
median barrier and maintenance vehicle pull-off design, shown below in Figure 3-36 and Figure 3-37.

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Figure 3-35: Sample E-ZPass Signing Plan (Added Lane)

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Figure 3-36: Sample E-ZPass Signing Plan (Dropped General-Purpose Lane)

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Figure 3-37: Concrete Median Barrier Design Special 1 Detail

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Figure 3-38: Concrete Median Barrier Transition Detail

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HOT LANE DESIGN CONSIDERATIONS

This section includes high-level design considerations and guidance to assist ITS practitioners engaged in
HOT lane design for MnDOT. Below is a list of several questions that designers should seek to answer as
they begin the HOT lane design process. The design of HOT lane facilities requires significant
coordination with the signing and pavement marking groups throughout the design process.
• How many segments will the HOT lane corridor be divided into? This is largely dependent on the
number of and spacing between interchanges. The 8 foot by 18 foot DMS pricing sign that is
typically used can list one or two segments, although if three segments need to be listed a 10
foot by 18 foot DMS will need to be used.
• Will enforcement zones be provided? Downstream enforcement will require intermittently wide
inside shoulders for State Patrol to park and enforcement beacons for State Patrol to determine
whether a violation has occurred. The enforcement device must be placed in close proximity to
the tolling antenna (within 10 feet along the structure).
• What is the interchange spacing? This drives what the toll reader and DMS pricing sign spacing
needs to be.
• At the start of a HOT lane, it is preferred to place the toll reader downstream of the second DMS
pricing sign below the regulatory E-ZPass sign, but they may need to be placed below the second
DMS pricing sign if sign spacing is not adequate.
• Will the HOT lane begin as an added lane or will the general-purpose lane drop and become the
HOT lane? It is preferred to begin the HOT lane as an added lane to reduce confusion and last-
minute lane changes.
• The controller cabinet should be placed as close as possible to the tolling antenna. The current
communications cable for the toll reader (LMR600 ¾-inch coaxial cable) has distance and
bending radius limitations, so the total length of the LMR600 cable should not be longer than
100 feet. Longer lengths must be analyzed and approved by MnDOT.
• The DMS pricing signs should be right-justified with the right edge of the DMS over the lane line
with the general-purpose lane and should not encroach on the general-purpose lane.
• Placement of DMS pricing signs should provide adequate time for drivers to decide if they want
to enter/stay in the HOT lane. See Figure 3-34 and Figure 3-35 for typical HOT lane design.
HOT LANE DESIGN PROCESS
General design steps for all ITS devices are listed in Section 4.7 and detailed design steps for HOT lanes
are listed in Section 4.8.4.

3.7.5. Ramp Meters

INTRODUCTION AND USAGE
Ramp metering is an effective strategy for reducing crashes and congestion on the freeway as well as
providing more reliable travel times. Ramp meters control the rate at which vehicles enter the mainline
such that the downstream capacity is controlled, thereby allowing the freeway to carry the maximum
volume at a uniform speed.
Another benefit of ramp metering is its ability to break up platoons of vehicles that have been released
from a nearby signalized intersection. The mainline, even when operating near capacity, can

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accommodate merging vehicles one or two at a time. However, when platoons (i.e., groups) of vehicles
attempt to force their way into freeway traffic, turbulence and shockwaves are created, causing the
mainline flow to breakdown. Reducing the turbulence in merge zones can also lead to a reduction in
sideswipe and rear-end type accidents that are associated with stop-and-go, erratic traffic flow.
MnDOT has researched the use of ramp meters extensively. This research found that the use of ramp
metering results in increased vehicle throughput, decreased travel times, increased speeds, improved
trip reliability, and fewer crashes on freeways. The capacity of a metered freeway is higher than an
unmetered freeway. The Transportation Policy Plan documents that metered freeways have a higher
capacity than unmetered freeways with 1,950 versus 1,750 vehicles per hour per lane, respectively.
Ramps may be metered as one lane, as two metered lanes, as two metered lanes with an HOV bypass,
and as two metered lanes with a metered HOV bypass. The single lane metering applies only to retrofit
situations where widening of a ramp or loop is not practical, and in some cases to new construction
where the RTMC decided to implement one lane metering. In all other cases, a two-lane metering of the
on-ramps and loops shall be designed.
Figure 3-39: Ramp Meter

When first implemented, MnDOT operated ramp meters by time of day. For the past 30 years, MnDOT
has used adaptive ramp metering. The adaptive ramp metering algorithm is incorporated into their
ATMS (IRIS) along with field devices (ramp meters, ramp detection, and mainline detection) to operate
the ramp metering system. IRIS looks at freeway operations three miles downstream of the ramp meter
or to the closest bottleneck.
COMPONENTS
Typical components required for a ramp meter project are shown in Table 3-19 along with a reference
to the section of this manual discussing the component.

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Table 3-19: Ramp Meter Components

Component Discussion
Ramp Meter Signals and Mounting This Section
Control Cabinet Section 3.5
Power Section 3.1
Communications Section 3.2
RAMP METER SIGNALS AND MOUNTING
Ramp meter pedestal poles are no longer painted and are spun anodized aluminum.
One-Way Ramp Control Signal Detail:
http://www.dot.state.mn.us/rtmc/pdfdgn_design/ramp/ONE%20WAY%20RAMP%20CONTROL%20SIGN
AL_dt1.pdf
RAMP METER DESIGN CONSIDERATIONS
Ramp Meter Signal Placement
Depending on the geometric layout of the ramp, the ramp meter type and ramp meter signal placement
need to be determined. This placement involves many factors, including:
• Are one-way or two-way ramp meter signals needed based on the ramp geometry?
• The placement of the ramp meter signals must consider providing adequate acceleration
distance and queue storage. The designer should work with the RTMC operations group to
determine the optimal design.
Ramp Meter Cabinet Placement
Once the ramp meter type, ramp meter signal placement, and geometric layout of the ramp have been
determined, the placement of the controller cabinet can be established. This placement involves many
factors, including:
• Visibility of the signals from the controller cabinet
• Distance between the controller cabinet and the loop detectors
• Distance between the controller cabinet and the signals on the ramp
• Safety of the cabinet location (do not place the cabinet on the outside of a curve)
• Grades
• Drainage
• Maintenance accessibility (parking availability for maintenance vehicles)
For maintenance considerations, it is preferred that the signals be visible from the controller cabinet,
but this is not always possible. The distance between the cabinet and equipment is also of concern,
since longer distances may require heavier gauge cables typically not used in standard ramp meter
design. Section 3.1.8 discusses cable sizing and voltage drop calculations. Heavier gauge cables can be
used where required, but they increase the number of different cables on a contract and increase
construction costs.

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It should also be noted that only four ramps can be run out of one cabinet for ramp metering. For cases
with more than four ramps, such as a cloverleaf interchange with ramps for all eight movements, at
least two cabinets would be needed if all ramps were to be metered.
The slope of the terrain for cabinet placement must be no steeper than 4:1. Placement of the cabinet on
3:1 slopes or steeper require grading provisions to provide a level area around the cabinet.
Loop Detector Placement
Demand, passage, and queue loop detection required for ramp meter installations are typically
illustrated at precise locations in the ramp meter plans. The plans should provide all loop detection
information including location (station), description (type), and size (in feet). When placing queue loop
detection for ramp meter applications, the designer should work with RTMC operations to determine
the optimal location. MnDOT uses four turns per loop detector; additional details can be found in the
MnDOT Standard Plans.
Detection is a critical component of effective ramp meter operations. Accurate detection on the
mainline and ramps is crucial for effective adaptive ramp metering. Further information on detection
can be found in the detection Section 3.7.1.
Advance Warning Sign Placement
Placement of a traditional advanced warning sign (e.g., “Ramp Metered When Flashing”) depends upon
the functional intent of the warning signs.
• Pre-Entrance Notification: Under pre-entrance notification, the functional intent of the sign is to
warn motorists approaching the ramp that it is currently being metered. The placement of
advance warning signs under this scenario should provide adequate sight distance along the
cross street, allowing the motorist ample time to decide whether to enter the freeway system at
that location, or bypass the ramp meter and travel along alternate routes.
• Post-Entrance Notification: Under post-entrance notification, the functional intent of the sign is
to warn motorists upon entering the ramp that metering is currently being implemented. The
placement of advance warning signs under this scenario should provide adequate sight distance
upon entering the ramp while allowing sufficient distance between the sign and estimated back
of queue.
RAMP METER DESIGN PROCESS
General design steps for all ITS devices are listed in Section 4.7 and detailed design steps for ramp
meters are listed in Section 4.8.5.

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4. Plans, Specifications, and Estimate (PS&E) Design Steps

4.1. General
The objective of this chapter is to present the fundamental procedures and standard practices related to
the design of ITS. The final product of the pre-construction activities in ITS design is the plans and Special
Provisions. Supporting the plans and Special Provisions are the standard design practices, Standard
Plates Manual, the Minnesota Standard Specifications for Highway Construction, other applicable
national and local standards, and any necessary agreements.

4.1.1. Required Sheets

Standard ITS design plans shall contain at least the following sheets:
• Title Sheet
• General Layout Sheets (showing location of plan sheets)
• TMS Components & Standard Plates
• Utility Listings & Construction Notes
• Estimated Quantities
• Construction Plans
• Detail Sheet Tabulation
• Details Sheets (may include one or more of the following)
• Pull Vault Detail
• Fiber Optic Pull Vault, Splice Vault, and Splice Vault Installation
• Typical Foundation Details
• Install Fiber Optic (FO) Patching Shelter
• Cabinet Details
• Signing Layout Details
• Sign Structural Details
• Loop Detector Details
• DMS Grounding Typical
• Video Camera Pole Detail and Pole Installation Detail
• Pole Mounted Fiber Termination Cabinet
• Buried Cable Sign Placement Detail
• Guardrail Installations
• End Treatment Details
• Fiber Distribution Equipment Details and Cable Labeling Details
• Other(s)
• Communications Schematics/Testing
• Standard Plan Sheets
• Signing Plans
• Other(s)
Section 4.7 in this chapter illustrates the steps followed to complete the design process for ITS design.
The ITS sample plan is available from the OTE website at http://www.dot.state.mn.us/its/design.html.

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4.1.2. Sheet Size and Scale

Final ITS plans should be prepared on 11 by 17 inch plan sheets. The original title sheet shall be of
vellum composition. The scale for the construction plans shall be 100 scale. Each sheet of the plan must
be properly identified in the lower right corner (State Project or State Aid Project Number and Sheet XX
of XX).
The licensed professional engineer responsible for or under whose supervision the work is performed
shall sign the title sheet.

4.1.3. CADD Standards

MnDOT and the RTMC have specific CADD standards that should be followed. MnDOT’s Computer Aided
Engineering Services (CAES) Unit develops CADD standards. MnDOT’s website for CADD Resources and
Data Standards is: http://www.dot.state.mn.us/caes/index.html.
MnDOT CADD Standards are documented here: http://www.dot.state.mn.us/caes/files/pdf/mndot-
caddstandardsdocumentation.pdf.
There are a variety of tables, tabulations, and notes that are created and inserted into the plans. These
items are created in Word and Excel and are imported into MicroStation using MS Office Importer rather
than creating them in MicroStation. This process is required by CAES standards and it is important so
that there is consistency with items such as font, text size, line weights, row heights, and column widths.
It is also considerably more efficient to create and edit these documents in Word and Excel.
RTMC specific standards for font number, text size, line types, and levels are shown below:

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4.2. Typical Plan Sets and Components

4.2.1. Title Sheet
The title sheet is required for all ITS plans. It includes information such as the title block, project
location, governing specifications, etc. A sample title sheet is shown below. Primary components of this
sheet are further described later in this subsection. Contact the project manager to obtain project
boundaries.

PLAN DESCRIPTION AND LOCATION

This defines the type of work being performed and the location of the work. The location identified
should list intersections from west to east or south to north.

GOVERNING SPECIFICATIONS AND INDEX OF SHEETS

This defines the governing specifications for the project, the project funding, and the index of sheets
contained within the plan set. Generally, it is located in the upper right-hand corner of the title sheet,
under the Federal Project number or statement “STATE FUNDS”.

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FIELD REVISIONS CERTIFICATION NOTE

This identifies:
• Who the plan set was developed by (or under the direct supervision of)
• That individual’s state of Minnesota registration information.

This block is located under the index of sheets.

Note: On the title sheet, after the state project number, the trunk highway and legislative route number
must be shown in parenthesis (T.H. 156 = ###) where ### is the legislative route number.
SIGNATURE BLOCK
The designer should consult with the project manager to ensure that the appropriate signature block is
used. Chapter 1 of the MnDOT Design Scene includes a flowchart for determining which signatures are

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required. The Design Scene is located at the link below, and a screenshot of the flowchart is included
below.
http://www.dot.state.mn.us/pre-letting/scene/index.html

The image below shows the signatures that are required for a typical State Transportation Improvement
Plan (STIP) project. This block is located below the Plan Preparation Certification note.

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PROJECT NUMBERS AND SHEET NUMBERS

The project numbers and sheet numbers are shown in the lower right-hand corner of the title sheet and
on all other sheets. For revisions to the plan made after project advertisement, an “R” shall be used
after the sheet number. For stand-alone ITS projects all sheets are numbered numerically, but for
projects where the TMS plans are part of a larger plan set the TMS sheets are numbered with the prefix
SZ (e.g. SZ01) and are included at the end of the plan set after all the numerical sections. This is typically
done for all functional group plans outside the construction group, including Traffic Control Plans (TC),
Permanent Pavement Marking Plans (PM), Lighting Plans (SL), Signing Plans (ST), Traffic Management
System Plans (SZ), and Traffic Control Signal System Plans (SS).

A SP in the project number stands for State Project. A SP is necessary for any project on a trunk highway.
A SAP is a State Aid Project number indicating that the local agency is using State Aid funds to finance
their share of the project. If the project has federal funding, the SAP becomes a SP. All state aid numbers
should be listed on all sheets to which they apply.
The general format for a SP number is “CCNN-A”. CC is the county number in alphabetical order (i.e.,
Anoka County is 02). NN is the control section number within the county that is unique to the roadway
in the county. A is the number of the project on that control section (i.e., 269 means that there have
been 268 other projects on this section of roadway prior to this project).
The general format for a SAP number is CCC-NNN-A. CCC is a 3-digit city number and a two-digit number
is a county number. NNN is a number related to the roadway and project type. A is the number of the
project in that city or county of that type.
INDEX MAP
The index map is used to identify the location of the project(s) and/or project work areas. Provide leader
lines from the beginning and end of the project limits to the appropriate points on the map. This is
generally located near the center of the title sheet.

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If appropriate, identify all SAP numbers applicable to the project. Also, label all individual device
locations such as DMS, RWIS, video camera, etc. if it is a device-specific project.

PROJECT LOCATION
The information included in this block is the generalized location (county and city). This is generally
located in the lower right part of the title sheet, left of the signature block, and above the project
number block.

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PLAN REVISIONS BLOCK

This block is included so that future revisions can be documented. This is generally located in lower
center portion of the title sheet. Pencil in the charge identifier number. MnDOT plan processing will edit
this as necessary.

4.2.2. General Layout Sheets

The general layout sheets show the general orientation and location of the construction plan sheets and
major TMS components within the project area.

4.2.3. TMS Components & Standard Plates Sheet

The TMS Components & Standard Plates sheet is required for all ITS plans. It includes information such
as the legend of symbols and applicable standard plates. A sample TMS components sheet is shown
below. Primary components of this sheet are further described later in this subsection.

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LEGEND OF SYMBOLS
These are the standard symbols pertaining to TMS design.

STANDARD PLATES SUMMARY

This identifies the list of Standard Plates that are applicable to this project.

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4.2.4. Utility Listings & Construction Notes Sheet

The Utility Listings & Construction Notes sheet is required for all ITS plans. It includes information such
as the utility listing for each work area, utility notes, and general construction notes. A sample Utility
Listings & Construction Notes sheet is shown below. Primary components of this sheet are further
described later in this subsection.

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UTILITY NOTES
These are the general Utility Notes.

Utility quality level is a professional opinion about the quality and reliability of utility information. There
are four levels of utility quality information, ranging from the most precise and reliable, level A, to the
least precise and reliable, level D. The utility quality level must be determined in accordance with

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guidelines established by the Construction Institute of the American Society of Civil Engineers in
document CI/ASCE 38-02 entitled “Standard Guidelines for the Collection and Depiction of Existing
Subsurface Utility Data.”
According to Minnesota Statutes, section 216D.04, subdivision 1a, all plans for projects with excavation
must depict the utility quality level of the utility information. Unless there is proof that the utility
information in the plan is more accurate, MnDOT assumes that it is Utility Quality Level D. The project
manager must use the following note, filling in the appropriate utility quality level, on the utility
tabulation sheets for projects involving excavation:
The subsurface utility information in this plan is utility quality level ___. This utility quality level was
determined according to the guidelines of CI/ASCE 38- 02, entitled “Standard Guidelines for the
Collection and Depiction of Existing Subsurface Utility Data.”
The Minnesota statute on utilities can be found at the following web site:
https://www.revisor.mn.gov/statutes/cite/216D.04
The plans and/or specifications should call for GPS locating of as-built installed equipment and
underground cables to support future one-call locating requirements, as well as provisions for how the
contractor should mark their dig locations and what level of locating they must agree to when digging.
LIST OF UTILITY OWNERSHIP
This is the list of the utility ownership in the project area. The table includes a note of how the utilities
should be impacted (e.g., LEAVE AS IS).

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GENERAL CONSTRUCTION NOTES

These are the general construction notes.

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4.2.5. Estimated Quantities Sheet

This sheet shows the estimated quantities for the project. The total quantity and the quantity by project
number shall be shown.
The appropriate specification item numbers, item descriptions, and units using the State’s pay item list
shall be included.
Refer to the AASHTOWare Project Item List website
(http://transport.dot.state.mn.us/Reference/refItem.aspx) for a listing of the following:
• Item number and extension
• Long description
• Short description
• Unit name
• Plan unit description
State Aid participation should be clearly identified for each item. The funding split note(s) should be
larger than the rest of the pay item notes as shown below for increased visibility. The pay item notes
should provide additional details that will assist the contractor with bidding on a plan set, such as
describing what a quantity consists of and if any service cabinets include circuit breakers that differ from
what is included in the APL.

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4.2.6. Construction Plans

At a minimum, the construction plan sheet(s) should include the following:
• Roadway geometrics (to scale)
• Background topography (grayscale)
• All graphics depicting ITS components
• Component installation notes
• Cabinet/equipment pad detail and notes
• Source of power notes (when applicable)
• Plan sheet title and revision block (on all sheets)
• A bar scale
• A north arrow
• Highway and/or street names
• Show utilities on the plan sheets on a case-by-case basis
• Blow-up of details, as needed, to clarify the area around video camera poles, NID poles,
cabinets, etc.
• Separate removal/proposed construction sheets in areas with highly congested linework to
clarify intent
• Staged projects than span several construction seasons may require individual staging plan
sheets. MnDOT requires a final plan set that shows a comprehensive view of the completed
TMS.

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4.2.7. Detail Tabulation

The detail tabulation sheet is a table of contents for the details included in the plans.

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4.2.8. Detail Sheets

The detail sheets show the standard details that are applicable to the project. They may include the
following details. Details are available here: http://www.dot.state.mn.us/rtmc/designplansheets.html
• Cabinet, Loop Detectors, Misc.
• Typical 334 Cabinet Installation
• Conduit Hanger Bracket
• Typical DMS 334 Cabinet Installation
• DMS Grounding/Installation
• Fiber Optic Cable Encasement
• Generator Connections
• Loop Detectors
• Pull Vault Installation
• Service & Grounding Installations
• Typical Foundations
• Cameras & NID
• Video Camera Pole Cabinet at Inplace Pole
• Video Camera Pole Installation
• NID Pole Installation
• NID Pole Cabinet

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• Fiber Optic Materials

• Proposed 10’x12’ TMS Shelter
• Proposed 12’x18’ TMS Shelter
• Buried Cable Sign Placement
• Fiber Optic Cable Labeling
• Fiber Optic Splice Vault Installation
• Fiber Optic Pull Vault at Splicing Locations Installation
• Ramp Meters
• Advance Flasher Signal
• Ramp Control Signals (One-Way and Two-Way)
• Ramp Control Signal Cable Termination Guide
• RCS Signing Layouts (With and Without HOV)
• Sign Structural Details
• Guardrail Installations
• End Treatment Details
• Other(s)

4.2.9. Communications Schematics/Testing

The Communications Schematics/Testing sheets include the schematic legend sheet and all
communications schematics that are required.

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4.3. MnDOT Standard Specifications for Construction

The MnDOT Standard Specifications for Construction (Spec Book) (see Figure 4-1) contains standard
specifications to be used and referred to in the design of plans and in the preparation of the Special
Provisions. Designers need to be aware of the specifications contained in the Spec Book that may apply
to their individual project.
The Spec Book is available online at http://www.dot.state.mn.us/pre-letting/spec/index.html. The Spec
Book is an online document that is typically updated every five years. The current version is the 2020
(lettings through 1/27/2022 use 2018). Also available online are the 2018, 2016, 2014, 2005, and 2000
editions.
Figure 4-1: MnDOT Standard Specifications for Construction

4.3.1. Format of the Spec Book

The Spec Book contains three divisions:
• Division I - General Requirements and Covenants
• Division II - Construction Details
• Division III - Materials
A section of Division I that all designers need to be particularly aware of, Section 1504, is shown in
Figure 4-2. That is because the order of precedence amongst contract documents is established in that
section.

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Figure 4-2: Spec Book 1504, Coordination of Contract Documents

4.3.2. Format of MnDOT 2550 (Traffic Management System)

Division II contains MnDOT 2550 (Traffic Management System).
The format of MnDOT 2550 is as follows:
• Description:
• List of acronyms
• Materials:
• General information section
• Specifies various materials, including references to Division III of the Spec Book
• Construction Requirements:
• Specifies the requirements for constructing a TMS
• Method of Measurement:
• Traffic Management Systems are measured by the various system components by the
units of measure required by the contract
• Basis of Payment:
• There is a payment schedule listed in this section that shows the Item No., Item, and
Unit
Division III includes a section entitled “Electrical Systems Materials” that contains various material
specifications for TMS. Many of these material specifications are referred to by MnDOT 2550. The
format of these material specifications is divided into Scope, Requirements, and Inspection and Testing.

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4.3.3. Other Standards

There are other national and local standards which are applicable to ITS plans and specifications. The
following are some of the standards specified in the Spec Book:
• American Association of State Highway and Transportation Officials (AASHTO)
• American Society of Testing and Materials (ASTM)
• Institute of Transportation Engineers (ITE)
• Insulated Cable Engineers Association (ICEA)
• National Electrical Code (NEC)
• National Electrical Manufacturers Association (NEMA)
• National Electrical Safety Code (NESC)
• Rural Utilities Service (RUS)
• Underwriter Laboratories, Inc. (UL)

4.3.4. MnDOT Contract Proposal

CONTENTS
Each MnDOT project has a proposal. The proposal contains items such as:
• Addendums
• Notices to Bidders
• Appendices
• Special Provisions (by division, e.g. Divisions S, Division SS, Division SL, Division ST, Division SZ,
etc.)
• Attachments
• Contract Schedule (Bid Prices)
SPECIAL PROVISIONS
Special Provisions are defined as “Additions and revisions to the Standard and Supplemental
Specifications covering conditions peculiar to an individual project.”
Special Provisions are just that: “SPECIAL” provisions. If an item(s) is adequately addressed or specified
in the Spec Book, Standard Plates, Plan, or other contract documents, then that item(s) should not be
duplicated within the Special Provisions. All pay items that end in the 600s (i.e. ####.6##) will require a
Special Provision.
Division SZ covers Traffic Management Systems. Special Provisions will be formatted into several SZ
sections since there is an individual section for each pay item and several other categories. The Division
SZ base specification includes all boilerplate sections, and the designer needs to delete the sections that
do not apply to the project and, as needed, modify the sections that do apply to the project. The
Division SZ base specification is available on the RTMC design website at the link below:
http://www.dot.state.mn.us/rtmc/designplansheets.html
Division S is the overall Special Provision section that is included for all projects. The following describes
the typical Metro District process for completing Division S, so for all Greater MN districts the designer
should coordinate with the district to determine their requirements. The traffic group provides input on

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the Traffic portion of Time & Traffic within Division S for every project, and the construction group is
responsible for writing the Time & Traffic portion of Division S with input from the traffic group. The
construction group also provides input on contract duration, liquidated damages, and certain quantities
such as the need for truck mounted impact attenuators and construction surveying. The Central Office is
responsible for writing Division S and incorporates input from the traffic and construction groups. There
are a variety of pay items that need to be included in Division S for an ITS project. The Division S sections
required vary depending on the components (i.e. structural steel, concrete, erosion control, etc.)
included in the ITS project.
Other Special Provisions sections are only included if design in other functional areas require their
addition. They are typically completed by the functional group completing that portion of the design. A
list of other Special Provisions sections that may need to be included are:
• Division SB (Bridge)
• Division SL (Lighting)
• Division SS (Signals)
• Division ST (Signing)
ADDENDUM
At times it may become necessary to provide additional information, corrections, additions, or deletions
to the Special Provisions, plans, and/or Spec Book after the project is advertised but before the actual
letting of the project. This information is provided to bidders via an addendum. This addendum is then
sent out to contractors, suppliers, etc. that have purchased the contract documents for the specific
project. This addendum is sent out with enough lead time to allow bidders the opportunity to consider
the addendum as they prepare their bid.
SUPPLEMENTAL AGREEMENTS
It is important that plans and Special Provisions are clear, accurate, and adequately indicate the work
that the contractor is required to perform. However, when that does not happen, or if some item(s) is
inadvertently omitted from the project documents, MnDOT will negotiate a supplemental agreement
with the contractor to rectify the situation. There are occasions when supplemental agreements are
necessary due to field conditions that were not apparent at the time of the project design. It is,
however, in the best interest of everyone to try and keep supplemental agreements to a minimum.

4.4. Approved/Qualified Products List

The MnDOT APL/QPL for Traffic Management Systems/ITS can be found by visiting
http://www.dot.state.mn.us/products/trafficmgtsystems/index.html.

4.5. Pay Items

Information on Pay Items can be obtained from the AASHTOWare Project Item List website:
https://transport.dot.state.mn.us/reference/refItem.aspx.
The website includes a search box to look for individual items (see Figure 4-3). The results will list the
item by:
• Item Number

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• Short Description
• Long Description
• Unit Name
• Plan Unit Description
• Specification Year
The results, or the entire AASHTOWare list, can be export to PDF and CSV formats.
Figure 4-3: AASHTOWare Website

4.6. Tabulation/Statement of Estimated of Quantities

In order to develop a cost estimate for the TMS, the designer needs to develop a "Tabulation/Statement
of Estimated Quantities" for all system component parts. This section is a Tabulation of Estimated
Quantities if the system is part of a larger plan and a Statement of Estimated Quantities if it is a stand-
alone TMS plan. When determining TMS quantities, the designer should determine quantities on a by-
sheet/by-location basis in order for discrepancies to be more easily checked. Certain pay items require
adjustment to increase quantities to appropriately consider factors such as wire slack and changes in
grade on conduit length. When developing the Engineer’s Estimate, even though they are not listed in
the Statement of Estimated Quantities, the designer must include State-provided materials (i.e. back-
sheet item) since they are project costs.

4.7. General Design Steps

This section covers the general design process for all ITS infrastructure, and design guidance for each ITS
component is discussed in detail in their respective sections which are linked below:
• Supporting Infrastructure Design: Section 3
• Power Distribution: Section 3.1
• Communications: Section 3.2

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• Conduit: Section 3.3

• Conduit Access: Section 3.4
• Equipment and Service Cabinets and Shelters: Section 3.5
• Additional Supporting Infrastructure (Posts and Poles, Foundations, Guardrails, Pull Off
Areas and Grading): Section 3.6
• ITS Device Design: Section 3.7
• Vehicle Detection: Section 3.7.1
• Video Cameras: Section 3.7.2
• Dynamic Message Signs: Section 3.7.3
• HOT Lanes: Section 3.7.4
• Ramp Meters: Section 3.7.5
Detailed design steps for the ITS devices are discussed in the following sections of this manual:
• Vehicle Detection: Section 4.8.1
• Video Cameras: Section 4.8.2
• Dynamic Message Signs: Section 4.8.3
• HOT Lanes: Section 4.8.4
• Ramp Meters: Section 4.8.5
Table 4-1: General Design Steps
Design Step Design Consideration
Design Step 1: Determine device- • See the relevant ITS Device Design sections referenced above to
specific details for all proposed ITS determine device-specific details and preliminary locations for all
components, and determine devices.
preliminary device locations
Design Step 2: Get accurate • Obtain all as-built TMS plan sheets, structure inspection reports,
drawings of the proposed ITS design and structural shop drawings for the proposed ITS design
locations locations from Georilla, eDIGS, and as-built books at the MnDOT
RTMC design office.
• Request or obtain base mapping for the proposed ITS design
locations. Files that may be available are existing topographic
survey files, proposed design files, existing utility files, and the
overall TMS base file. Retain coordinates within the CADD file (if
possible).
• MnDOT uses MicroStation and all plans are to be produced using
MicroStation. The use of “Models” within MicroStation will not be
accepted. If there are multiple phases of TMS construction, each
phase of design must be contained in individual files.
Design Step 3: Refine locations of • Review all as-built TMS plan sheets for the proposed ITS design
the proposed ITS devices locations to identify any possible issues, and to gain a better
understanding of existing conditions prior to the site visit.
• See the relevant ITS Device Design sections linked above to refine
locations of the proposed ITS devices. There are various design
considerations that need to be made for each device.

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Design Step Design Consideration

Design Step 4: Conduct a site visit • Plan details of the site visit prior to going into the field. Are two
staff required for safety? Are there site-specific elements that
would affect where you should park (bridges, continuous
guardrail, narrow shoulders, etc.)? Are any specialized tools
required? Do you need access into existing ITS cabinets,
handholes, or pull vaults? Is traffic control or a bucket truck
needed to safely access the site?
• Notify MnDOT in advance of the site visit. For shorter duration
visits with minimal impact to traffic, notify the MnDOT project
manager and RTMC. For longer duration or if traffic disruptions
are required, the 511 Coordinator needs to be contacted.
• Review the site to determine where existing power and a
connection to inplace communications infrastructure is available.
The review of existing conditions is often simpler in rural areas as
opposed to urban areas although there are locations in rural
areas that are very challenging to obtain power or a connection
to inplace communications infrastructure.
• Review all inplace components in the field. Will any existing ITS
infrastructure need to be removed or relocated due to their
condition, possible conflicts with proposed ITS infrastructure,
etc.?
• Review terrain at proposed component location, site drainage,
line of sight, etc.
• Take photos of everything and make sketches to confirm cable
routing and component locations, etc. Create notes that identify
the locations and view of each photo in the field.
Design Step 5: Revise ITS device • Review site visit information and as-built information and revise
locations as needed, determine the ITS device locations. At this point locations are driven primarily by
source of power location, and obtaining reasonable access to power and communications and
identify where the connection to adjustments that are warranted based on findings during the site
existing communications visit.
infrastructure will occur • See the relevant ITS Device Design sections linked above for
various design considerations that need to be made for each
device.
• Finalize locations of ITS devices.
• Request any additional survey, geotechnical data, or other
information needed. Survey is required at locations where there
is not accurate base mapping. Soil borings are required at all
proposed overhead sign structure footing locations.
• When there is excavation, start the MnDOT Utility Coordination
Process. If this design is being included as part of a larger roadway
design project, MnDOT Utilities may handle this process.
Design Step 6: Lay out the proposed • Lay out all proposed ITS devices and supporting infrastructure in
ITS devices and supporting MicroStation. Supporting infrastructure that may be required
infrastructure in MicroStation includes control cabinet, service cabinet, source of power,
communications, pull vaults, and conduit runs.

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• Determine which components are State-provided.
• See the relevant ITS Device Design sections linked above for
typical layouts and design considerations for each device
installation. A general description of what may be required is
listed below:
• Structure for ITS device
• ITS device (there can be multiple ITS devices at each site)
• 334 series cabinet
• Service cabinet (with a meter) located near the source of
power (SOP)
• Service cabinet type special (without a meter) located near
the pole cabinet or 334 series cabinet if there is a long
distance from the service cabinet (with a meter), access
road, or if physical barriers are present
• SOP (coordinated by designer, installed by power company,
power company costs are a project cost) after SOP location
and type is determined
• Some general items to consider when placing cabinets are:
• Place within right-of-way
• Place higher than adjacent pull vaults to keep water from
running into cabinet
• Locate to avoid interference with pedestrians
• Consider snow storage so access can be maintained during
the winter
• If the 334 series cabinet is not near the service cabinet, a
service cabinet type special should be installed near the 334
series cabinet to facilitate more efficient and safe access to
shut off power to devices
• The 334 series cabinet should be located behind a guardrail
or outside the clear zone
• Consider access to potential fiber optic trunk line and
existing splice points
Design Step 7: Determine SOP and • See Section 3.1.3 for detailed design guidance on power services.
coordinate with utility company
Design Step 8: Add conduit runs, pull • See Sections 3.3 and 3.4 for details on conduits and conduit
vaults, and cables access.
• See Section 3.1.8 for details on load requirements, breaker sizing,
and voltage drops to determine the size of power cables needed
for the circuits serving each ITS device and from the SOP.
• See Section 3.2 for more information on communications and
each ITS device section linked above for device-specific design
guidance.
Design Step 9: Size conduits • See Sections 3.3.2 and 3.3.3 for design guidance.
Design Step 10: Annotate plans • See each ITS device section linked above for device-specific plan
sheet annotations. The designer needs to coordinate with the

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project manager to assign device names for all the proposed ITS
devices. Cabinet and pole names are based on roadway and
location relative to the reference point.

4.8. Detailed Design Steps

4.8.1. Vehicle Detection
Table 4-2: Vehicle Detection Design Steps

Design Step Design Consideration

Design Step 1: Determine all • What is the condition of the existing roadway? For existing mainline
required detection locations loop detectors, depending on the existing roadway condition and
the number of mainline loops being replaced, the designer may
choose to abandon the existing loops and install microwave
detection.
• Inductive loops and microwave detection:
• Project may require repairs/replacement of existing
detection or that new detection be installed, whether it is
inductive loops or microwave detection
• Input from RTMC operations is required
• Designer should determine the location of all required
detection based on the design considerations above and
the RTMC standard detail sheets available online at:
http://www.dot.state.mn.us/rtmc/designplansheets.html.
• Microwave detection:
• Determine if the detector can be mounted on an existing
pole or if it will require its own pole
Design Step 2: Get accurate • See General Design Step 2, Section 4.7.
drawings of the proposed
detection locations
Design Step 3: Refine location of Microwave detection:
microwave detection • Modify the location of the proposed detector(s) based on the
following:
• Can the detector be mounted on a video camera pole or
will it require its own pole? It must be serviceable.
• If a new pole is needed, calculate the clear zone distance at
the proposed detection location. The pole should be
sufficiently outside the clear zone, but if this isn’t possible it
must be placed behind guardrail.
• Obtain a cross section at the proposed detection location to
determine the detector mounting height and pole height
based on Table 3-11. MnDOT typically chooses a mounting
height between the recommended and maximum
whenever possible.

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• Review Section 3.7.1 design guidelines and check for
potential conflicts.
• Review the modified location one final time to make sure there are
no major concerns that justify another adjustment to the detector
location.
Design Step 4: Conduct a site visit • See General Design Step 4, Section 4.7.
Design Step 5: Refine detection Inductive loops and microwave detection:
locations, source of power, and • Review site visit information and as-built information and refine
connection to existing detector location(s). At this point, the detector locations will
communications infrastructure. typically not be modified much as they are determined primarily
by the standard details. The 334 series cabinet (if required)
should be located close to the detectors, and power and
communications (if required) should be brought to the control
cabinet location whenever possible. Solar power and cellular
modems may be used as a last resort for some rural locations.
Approval from the MnDOT ITS project manager must be obtained
if solar power or cellular modems are used.
• If a cellular modem or solar power are selected: 1) check cellular
signal strength in the area for the provider MnDOT uses and 2)
make sure the proposed site is clear of vegetation over-canopy,
so the solar panels will receive unimpeded sunlight.
• Finalize detector locations.
Design Step 6: Lay out proposed Inductive loops:
detection and any related TMS • The following components are typically required as part of a new or
components existing inductive loop detection installation: inductive loops, 334
series cabinet, service cabinet, and SOP.
• A typical layout for a loop detector installation includes the
following TMS components:
• Inductive loops in pavement, either sawcut or preformed
depending on pavement conditions
• SOP (coordinated by designer, installed by power company,
power company costs are a project cost) after SOP location
and type is determined
• Service cabinet (with a meter) located near the SOP
• Service cabinet type special (without a meter) located near
the pole cabinet if there is a long distance from the service
cabinet (with a meter), access road, or if physical barriers
are present
• 334 series cabinet
• Position components in the design file.
Microwave detection:
• The following components are typically required as part of a new
detection installation: NID device, NID pole, pole cabinet, service
cabinet, and SOP.

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• The microwave detector is State-provided and installed, and the
pole cabinet and pole are furnished and installed by the
contractor.
• A typical layout for a new detector installation includes the
following TMS components:
• NID pole or mounting support to attach the detector to an
existing structure
• Non-intrusive detector
• SOP (coordinated by designer, installed by power company,
power company costs are a project cost) after SOP location
and type is determined
• Service cabinet (with a meter) located near the SOP
• Service cabinet type special (without a meter) located near
the pole cabinet if there is a long distance from the service
cabinet (with a meter), access road, or if physical barriers
are present
• Pole cabinet
• Position components in the design file.
• Guardrail may be required to protect the NID pole and provide a
safe work area. Incorporate into the design, or if part of a larger
project coordinate with the roadway designer. If guardrail is added,
review grades as often additional grading is required.
Design Step 7: Determine SOP and Inductive loops:
coordinate with utility company • See General Design Steps, Section 4.7.
• See Table 3-2 for the amp load for a 334 series cabinet.
• 120 VAC is required for a 334 series cabinet.
• See subsection Breaker Sizing for the circuit breaker size to be used
in a service cabinet for a 334 series cabinet.
Microwave detection:
• See General Design Steps, Section 4.7.
• See Table 3-2 for the amp load for a pole cabinet serving a NID.
• 120 VAC is required for a pole cabinet serving a NID.
• See subsection Breaker Sizing for the circuit breaker size to be used
in a pole cabinet serving a NID.
Design Step 8: Add conduit runs, See General Design Steps, Section 4.7.
pull vaults, and cables • Inductive loops:
• Inductive loops use a 2/C No. 14 cable
• Microwave detection:
• Detectors typically use an armored fiber optic pigtail cable
(6SM) for communications to the pole cabinet
• Power cable is typically 1-3/C No. 14 from the service cabinet
to the pole cabinet, with a separate circuit breaker installed in
the service cabinet for the pole cabinet. Wire size will need to

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be increased if distances increase and voltage drops are too
high.
• The typical layout of conduit runs and pull vaults are as follows:
• Pull vault installed within 25’ of detector pole
• Two non-metallic conduits (NMC) between the pull vault
near the base of the detector support and the detector pole
cabinet with the detector power cables and fiber pigtail
• One empty NMC between the pull vault near the base of
the detector support and the detector pole cabinet for
future needs.
• One NMC between the pull vault near the base of the
detector pole and the service cabinet with power cables for
the pole cabinet
• One NMC between the service cabinet and SOP with power
cables
• One NMC between the control cabinet (if required) and the
pull vault near the base of the detector support that
includes the fiber pigtail.
• One NMC between the pull vault near the pole cabinet or
334 series cabinet (if required) and the nearest splice vault
with a fiber pigtail to connect to the fiber optic trunk line.
Additional pull vaults may be needed along this conduit
path if the distance or route to the fiber optic trunk line
necessitate additional locations.
Design Step 9: Size conduits • See General Design Step 9, Section 4.7.
Design Step 10: Annotate plans • A plan example where the detection related components and
annotations are shown is available at:
http://www.dot.state.mn.us/its/design.html.
• Detectors are numbered/labeled according to the RTMC standard
details at:
http://www.dot.state.mn.us/rtmc/designplansheets.html.

4.8.2. Video Cameras

Table 4-3: Video Camera Design Steps
Design Step Design Consideration
Design Step 1: Determine general • Is an existing video camera being replaced or is it a new location?
video camera purpose and location • The designer should obtain the primary purpose of the video
camera and approximate location and highway where the video
camera is to be located from RTMC operations.
• If available, review preliminary design documents, project scoping
reports, and ideally the detailed scope of the project.
• Determine the following based on the video camera purpose and
highway characteristics:
• Video camera spacing

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• Available structure types for mounting
• Discuss and review proposed video camera locations with
RTMC operations staff to confirm that the design intent is
achieved
• Selection of video camera locations are based on
operational and maintenance requirements along with local
topography. Desired coverage dictates the general camera
location.
• Camera locations require a clear line of site to the desired
coverage area (consider tree canopy cover during the
summer). If necessary, use a camera-equipped vehicle to
validate video camera placement as a part of design
development.
• The following items should be considered when locating a video
camera in both urban and rural conditions:
• Typical spacing is 0.5-1 mile in urban areas. In rural areas,
longer distances are typically used; if using 1-2 mile spacing
the shorter pole should be used, and if up to 2-mile spacing
is desired the longer pole should be used. At longer
distances, wind has a more significant effect on camera
movement and can cause the video to bounce excessively.
Some corridors will not have video cameras while others
will just place video cameras at interchanges. In the Metro
District, the standard is a 50-foot pole and 1-mile spacing.
• Place on the outside of the curve
• Check for blind spots caused by other structures
• Locate so a maintenance vehicle can park safely near the
video camera and that a level area is available to use a
ladder (if applicable). A pull-off may be required.
• Avoid locations that require a lane closure to obtain access
to the video camera
• If being mounted on a folding pole, ensure the camera will
lower into an area where work can occur
• In rural areas, place on a higher elevation location such as
on bridge crossings to maximize view
• Galloping at longer distances is less of a concern with
modern image stabilization
• There is usually more flexibility in rural areas
• Pole height depends on topography
• Combining a video camera and NID on the same pole can be
considered
Design Step 2: Get accurate • See General Design Step 2, Section 4.7.
drawings of the proposed video
camera location

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Design Step 3: Refine location of • The goal of this step is to refine the location of the video camera
video camera provided initially to within 200 feet of its final design location
prior to completing the field visit.
• Modify the location of the proposed video camera considering
the following:
• Is the video camera located near an existing source of
power or communications connection? If it isn’t, can the
video camera be moved closer to the existing infrastructure
to reduce cost?
• Is there existing infrastructure that can be used to mount
the video camera (e.g. NID pole of appropriate height)?
• If the video camera is roadside mounted, can it be placed
outside the clear zone or is it possible/necessary to place
behind guardrail?
• If near a DMS, locate the video camera so the DMS can be
viewed by the video camera
• Plans must indicate which direction the folding pole should
fall. The pole cabinet needs to be downstream so the pole
folds over the cabinet.
• Review the modified location one final time to make sure there
are not any major concerns that justify another adjustment to the
video camera location (e.g., roadside mount would be in a pond,
steep slopes make video camera location impractical, etc.).
Design Step 4: Conduct a site visit • See General Design Step 4, Section 4.7.
• To verify video camera sight lines, a drone may be used. If there
are sight obstructions, use the drone to determine a better video
camera location.
Design Step 5: Refine video camera • Review site visit information and as-built information and refine
location, source of power, and video camera location. At this point, the location refinement is
connection to existing driven primarily by reasonable access to power and
communications infrastructure communications.
• If there is not a source of power located within a reasonable
distance (less than 1,200 feet) from the proposed video camera
location, consider relocating the video camera. Solar power is an
option for some rural locations.
• If there is not an existing communications connection located
within a reasonable distance (less than 1,200 feet) from the video
camera, consider relocating the video camera. Cellular modems
are an option for some rural location depending on video camera
use and if there is a reliable cell phone signal.
• If a cell phone modem or solar power are selected: 1) check cell
signal in the area for the provider MnDOT utilizes for cell service
and 2) make sure the proposed site is clear of vegetation over-
canopy, so the solar panels will receive unimpeded sunlight
• Finalize the location of the video camera.

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Design Step 6: Lay out proposed • The following components are typically required as part of a new
video camera related TMS video camera installation: video camera, mounting support (video
components camera folding pole, NID folding pole, or traffic signal pole), pole
cabinet, service cabinet, and SOP
• The video camera is State-provided
• A typical layout for a new video camera installation requires the
following TMS components:
• Mounting support to attach the video camera
• Video camera
• SOP (coordinated by designer, installed by power company,
power company costs are a project cost) after SOP location
and type is determined
• Service cabinet (with a meter) located near the SOP
• Service cabinet type special (without a meter) located near
the pole cabinet if there is a long distance from the service
cabinet (with a meter) or access road, or if physical barriers
are present
• Pole cabinet
• Position components into the design file.
• Guardrail may be required to protect the video camera pole and
provide a safe work area. Incorporate guardrail into the design, or if
part of a larger project coordinate with roadway designer. If
guardrail is added, review grades as often grading is required.
Design Step 7: Determine SOP and • See General Design Steps, Section 4.7.
coordinate with utility company • See Table 3-2 for the amp load for a pole cabinet serving a video
camera.
• 120 VAC power is required for the video camera.
• See subsection Breaker Sizing for the circuit breaker size to be used
in service cabinet for a pole cabinet serving a video camera.
Design Step 8: Add conduit runs, • See General Design Steps, Section 4.7.
pull vaults, and cables • Video cameras typically utilize Cat 5E cable for communications
and power between the pole cabinet to the video camera. If a 334
series cabinet is required in addition to the pole cabinet and it is
located close to video camera pole (less than 50 feet), then Cat 5E
cable is run to the video camera from the 334 series cabinet. In
cases where the 334 series cabinet is located more than 50 feet
from the video camera, a fiber pigtail is run to the pole cabinet
and an Ethernet switch is placed in the pole cabinet.
• Power cable is typically 1-3/C No. 14 from the service cabinet to
the pole cabinet, with a separate circuit breaker in the service
cabinet for the pole cabinet. Wire size will need to be increased if
distances increase and voltage drops are too large.
• The typical layout of conduit runs and pull vaults are as follows:
• Pull vault within 25 feet of video camera pole

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• Two non-metallic conduits (NMC) between the pull vault
near the base of the video camera support and the video
camera pole cabinet with video camera power cables and
fiber pigtail
• One empty NMC between the pull vault near the base of
the video support and the video camera pole cabinet for
future needs
• One NMC between the pull vault near the base of the video
camera pole and the service cabinet with power cables for
the video camera
• One NMC between the service cabinet and SOP with power
cables
• One NMC between the 334 series cabinet (if required) and
the pull vault near the base of the video camera support
that includes the fiber pigtail
• One NMC between the pull vault near the pole cabinet or
334 series cabinet (if required) and the nearest splice vault
with a fiber pigtail to connect to the fiber optic trunk line.
Additional pull vaults may be needed along this conduit
path if the distance or route to the fiber optic trunk line
necessitate additional locations.
Design Step 9: Size conduits • See General Design Step 9, Section 4.7.
Design Step 10: Annotate plans • A plan example where the video camera related components and
annotations are shown is available at:
http://www.dot.state.mn.us/its/design.html.
• Video cameras are labeled in order from west to east and south
to north.
• The designer needs to coordinate with the project manager to
determine camera numbers that may required coordination with
RTMC Operations.

4.8.3. Dynamic Message Signs

Table 4-4: DMS Design Steps
Design Step Design Consideration
Design Step 1: Determine general • Is an existing DMS being replaced, or is it a new location?
DMS purpose and location • Input from RTMC operations is required.
• Designer should obtain the primary purpose of the DMS and
approximate location and highway where the DMS is to be
located.
• If available, review preliminary design documents, project scoping
reports, and ideally the detailed scope of the project.
• Determine the following based on the DMS purpose and highway
characteristics:
• Mounting position (overhead or roadside mount)

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• Size and model of DMS
• Available structure types for mounting
• Is the DMS overhead and is it located on an oversize/overweight
(OSOW) permit route? If it is, the required minimum clearance
over the road needs to be reviewed. Maps for MnDOT OSOW
routes are available at the following link:
https://www.dot.state.mn.us/cvo/oversize/resources.html
Design Step 2: Get accurate • See General Design Step 2, Section 4.7.
drawings of the proposed DMS
location
Design Step 3: Refine location of • The goal of this step is to refine the location of the DMS provided
DMS initially to within 200 feet of its final design location prior to
completing the field visit.
• Modify the location of the proposed DMS considering the
following:
• A DMS should not be located where roadway geometrics
reduce sight distance below 800 feet
• If the sign is on a horizontal curve with a radius of 5,500’ or
less, the sign should be moved off the curve
• Is the proposed DMS location far enough in advance of the
location being signed or the intersection or interchange
where traffic may need to exit based on the message on the
DMS?
• Ideally a DMS is placed a minimum of 1 mile in advance of
the location of concern or intersection/interchange where
traffic would exit to avoid a signed condition
• Review distances to adjacent guide signs. Typical sign
spacing of 800 feet in each direction of the DMS to adjacent
standard guide signs must be maintained.
• If the DMS will be overhead, is there an existing bridge or
standard signing truss that could be utilized?
• If the DMS is roadside mounted, can it be placed outside
the clear zone or will it need to be placed behind guardrail?
If DMS location is near an at-grade intersection, the
designer needs to ensure that it does not negatively impact
intersection sight distances.
• The angle of skew needs to be reflected in the plans
• Review the modified location one final time to make sure there
are not any major concerns that justify another adjustment to the
sign location (e.g., roadside mount would be in a pond, steep
slopes make sign location impractical, etc.).
Design Step 4: Conduct a site visit • See General Design Step 4, Section 4.7.
Design Step 5: Refine DMS location, • Review site visit information and as-built information and refine
source of power, and connection to the DMS location. At this point, the location refinement is driven
existing communications primarily by reasonable access to power and communications.
infrastructure

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• If there is not a source of power located within a reasonable
distance (less than 1,200 feet) from the proposed DMS, consider
relocating the DMS. If the DMS cannot be relocated, power
should still be installed from the nearest SOP if possible.
• If there is not an existing communications connection location
within a reasonable distance (less than 1,200 feet) from the DMS,
consider relocating the DMS. Cellular modems are an option for
some rural location depending on DMS use and if there is a
reliable cell phone signal.
• If a cellular modem is selected check the cell signal in the area for
the provider MnDOT utilizes for cell service.
• Finalize the location of the DMS.
Design Step 6: Lay out proposed • The following components are typically required as part of a new
DMS-related TMS components DMS installation: DMS, sign structure, 334 series cabinet, service
cabinet, and SOP.
• The DMS and 334 series cabinet are State-provided.
• A typical layout for a new DMS installation requires the following
TMS components:
• Sign structure to mount the DMS to
• DMS
• SOP (coordinated by designer, installed by power company,
power company costs are a project cost) after SOP location
and type is determined
• Service cabinet (with meter) located near the SOP
• Service cabinet type special (without a meter) located near
the pole cabinet if there is a long distance from the service
cabinet (with a meter) or access road, or if physical barriers
are present
• 334 series cabinet
• Position components into the design file.
• Some general items to consider when placing cabinets are:
• Place within right-of-way
• Place outside the clear zone or behind guardrail
• Place higher than adjacent pull vaults to keep water from
running into cabinet
• Locate to avoid interference with pedestrians
• Ensure the front of DMS is visible from cabinet
• Consider snow storage so access can be maintained during
the winter
• 334 series cabinet should be relatively close to the service
cabinet, or a service cabinet type special should be
considered near 334 series cabinet
• Consider access to the fiber optic trunk line if applicable
• When ladder access is required to maintain ground-mounted
signs, the area must meet OSHA requirements. Pull-offs may also

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be required in some situations to allow for maintenance vehicles
to safely park to access the sign without significantly impacting
traffic. These need to be incorporated into the design by the ITS
designer, or if part of a larger project a roadway designer may
incorporate this into the design, but coordination is required.
• Guardrail is required for sign structures that are not breakaway. It
is often desired to protect cabinets and provide a safe work area.
The ITS designer needs to incorporate this into the design, or if
part of a larger project a roadway designer may incorporate this
into the design, but coordination is required.
Design Step 7: Determine SOP and • See General Design Steps, Section 4.7.
coordinate with utility company • See Table 3-2 for the amp load for the DMS model being used.
• 120/240 VAC power is usually required for DMS. Smaller DMSs
may only require 120 VAC.
• See subsection Breaker Sizing for the circuit breaker size to be
used in the service cabinet serving a DMS.
Design Step 8: Add conduit runs, • See General Design Steps, Section 4.7.
pull vaults, and cables • Communication cable between the DMS and the 334 series
cabinet is micro fiber optic cable (6-strand multimode).
• The power cable size serving the DMS varies based on the amp
load of the particular DMS and whether the DMS requires 120 or
120/240 VAC. The power cable size serving the 334 series cabinet
varies based on the proximity of the cabinet to the service
cabinet. See the Wire Gauge subsection for minimum wire size for
the various DMS sizes and 334 series cabinet. Wire size will need
to be increased if distances increase and voltage drops are too
large. Three cables are utilized for signs that require 120 VAC and
four cables are utilized for signs that required 120/240 VAC.
• The typical layout of conduit runs and pull vaults are as follows:
• Pull vault within 25 feet of the sign structure
• One non-metallic conduit (NMC) between a pull vault near
the base of the sign structure and sign structure with power
cables and communication cable
• One NMC between the pull vault near the base of the sign
structure and the service cabinet with power cables for the
DMS
• One NMC between the service cabinet and 334 series
cabinet with power cables for the 334 series cabinet
• One NMC between the 334 series cabinet and the pull vault
near the base of the sign structure that includes the
communication cables from the fiber optic trunk line to the
334 series cabinet, and from the 334 series cabinet to the
DMS
• One NMC between the pull vault near the base of the sign
structure and the nearest splice vault with a fiber optic
pigtail to connect the 334 series cabinet to the fiber optic

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trunk line. Additional pull vaults may be needed along this
conduit path if the distance or route to the fiber optic trunk
line necessitate additional locations.
• One NMC between the service cabinet and SOP with power
cables
Design Step 9: Size conduits • See General Design Step 9, Section 4.7.
Design Step 10: Annotate plans • A plan example where the DMS related components and
annotations are shown is available at:
http://www.dot.state.mn.us/its/design.html.

4.8.4. HOT Lanes

Table 4-5: HOT Lane Design Steps
Design Step Design Consideration
Design Step 1: Determine general • Is an existing HOT lane being modified or is it a new location?
locations for all required HOT lane • If available, review preliminary design documents, project scoping
facility components reports, and ideally the detailed scope of the project.
• Create a high-level layout depicting all inplace or proposed sign
bridges, roadway bridges, and entrance ramps.
• Significant collaboration between the RTMC and signing groups
will be required.
• Coordination may be needed between roadway design and ITS
design regarding placement of tolling antennas and enforcement
beacons, as the location of wide shoulders may change depending
on where tolling antennas need to be placed.
Design Step 2: Get accurate • See General Design Step 2, Section 4.7.
drawings of the proposed HOT lane
location
Design Step 3: Refine location of • Based on the as-builts, adjust the placement of the HOT lane
HOT lane components components to avoid conflicts with existing infrastructure.
Design Step 4: Conduct a site visit • See General Design Step 4, Section 4.7.
Design Step 5: Refine HOT lane • Finalize locations of HOT lane components. Each component has
component locations, sources of different placement considerations as detailed in Section 3.7.4.
power, and connections to existing
communications infrastructure

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Design Step 6: Lay out proposed • The following components are required as part of a new HOT lane
HOT lane related TMS components installation:
• DMS pricing signs
• Tolling antennas (need two for bi-directional HOT lanes)
• Enforcement shoulder
• Enforcement devices (ADEC TDC3 detector and
enforcement beacon)
• Controller cabinet (if the toll reader is in the cabinet, the
length of the LMR600 cable needs to be considered)
• Conduit
• Pull vaults
• Pavement markings and signing
• Complete an FCC filing for the tolling antenna (Part 90). See
Section 3.2.3 for more information.
Design Step 7: Determine SOP and • See General Design Step 7, Section 4.7.
coordinate with utility company • See Table 3-2 for the amp loads for the various tolling
components.
• 120 VAC power is required for the controller cabinet.
• See subsection Breaker Sizing for the circuit breaker size to be
used in the service cabinet serving a HOT lane.
Design Step 8: Add conduit runs, • See General Design Step 8, Section 4.7.
pull vaults, and cables • The power cable size serving the 334 series cabinet varies based
on the proximity of the cabinet to the service cabinet. See the
Wire Gauge subsection for minimum wire size for the 334 series
cabinet. Wire size will need to be increased if distances increase
and voltage drops are too large.
• Power cable for HOT lane TMS components are:
• DMS: see Wire Gauge subsection
• Tolling antenna: LMR600 cable (100’ maximum
recommended distance)
• Enforcement beacon lights: 6/C No. 14
• Detector/trigger: 3/PR No. 22
• The typical layout of conduit runs and pull vaults are as follows:
• Two pull vaults within 25 feet of 334 series cabinet, one for
power and one for communications
• One non-metallic conduit (NMC) between the power pull
vault and the 334 series cabinet with power cables
• One NMC between the communications pull vault and the
334 series cabinet with communication cables
• One NMC between the service cabinet and 334 series
cabinet with power cables for the 334 series cabinet
• One NMC between the service cabinet and SOP with power
cables
• One NMC between the 334 series cabinet and the nearest
splice vault with a fiber optic pigtail to connect to the fiber

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optic trunk line. Additional pull vaults may be needed along
this conduit path if the distance or route to the fiber optic
trunk line necessitate additional locations.
Design Step 9: Size conduits • See General Design Step 9, Section 4.7.
Design Step 10: Annotate plans • A plan example where the HOT lane related components and
annotations are shown is available at:
http://www.dot.state.mn.us/its/design.html.

4.8.5. Ramp Meters

Table 4-6: Ramp Meter Design Steps
Design Step Design Consideration
Design Step 1: Determine proposed • Is an existing ramp meter being replaced or is it a new location?
ramp metering location(s) and/or • If available, review preliminary design documents, project scoping
existing ramp metering location(s) reports, and ideally the detailed scope of the project.
to be modified • Evaluate geometric requirements and potential modifications for
the location. The MnDOT Road Design Manual provides guidance
related to ramp geometrics at ramp meter locations (see sections
6-2.07, 6-2.08, and 6-2.09).
• Determine if advance warning signs “Ramp Metered When
Flashing” should be included.
Design Step 2: Get accurate • See General Design Step 2, Section 4.7.
drawings of the proposed ramp
meter location
Design Step 3: Refine location of • Based on the as-builts, adjust the placement of the ramp meters
ramp meter to avoid conflicts with existing infrastructure.
Design Step 4: Conduct a site visit • See General Design Step 4, Section 4.7.
Design Step 5: Refine ramp meter • Finalize the location of ramp meter signals. The ramp meter
location, source of power, and location is driven by the ramp geometrics, so the source of power
connection to existing and communications will always need to come to the ramp meter
communications infrastructure cabinet location.
Design Step 6: Lay out proposed • The following components are required as part of a new ramp
ramp meter related TMS meter installation:
components • Ramp meter signals
• Controller cabinet
• Detection:
• Queue loop(s)
• Passage loop(s)
• Conduit
• Pull vaults
• Pavement markings and signing
• Advanced warning signs and beacons (if required)
Design Step 7: Determine SOP and • See General Design Step 7, Section 4.7.
coordinate with utility company • See Table 3-2 for the amp loads for the ramp meter components.
• 120 VAC power is required for the controller cabinet.

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• See subsection Breaker Sizing for the circuit breaker size to be used
in the service cabinet for a 334 series cabinet serving a ramp meter
site.
Design Step 8: Add conduit runs, • See General Design Step 8, Section 4.7.
pull vaults, and cables • The power cable size serving the 334 series cabinet varies based
on the proximity of the cabinet to the service cabinet. See the
Wire Gauge subsection for minimum wire size for the 334 series
cabinet. Wire size will need to be increased if distances increase
and voltage drops are too large.
• Power cable used for each ramp meter signal is 1-6/C No. 14.
• For power cable runs longer than 1000 feet, use 2-6/C No.14 per
ramp meter signal.
• The typical layout of conduit runs and pull vaults are as follows:
• Two pull vaults within 25 feet of 334 cabinet, one for power
and one for communications
• One non-metallic conduit (NMC) between the power pull
vault and the 334 series cabinet with power cables
• One NMC between the communications pull vault and the
334 series cabinet with communication cables
• One NMC between the service cabinet and 334 series
cabinet with power cables for the 334 series cabinet
• One NMC between the service cabinet and SOP with power
cables
• One NMC between the 334 series cabinet and the nearest
splice vault with a fiber pigtail to connect to the fiber optic
trunk line. Additional pull vaults may be needed along this
conduit path if the distance or route to the fiber optic trunk
line necessitate additional locations.
• Conduits connecting loop detector lead-ins to the 334
cabinet
Design Step 9: Size conduits • See General Design Step 9, Section 4.7.
Design Step 10: Annotate plans • A plan example where the ramp meter related components and
annotations are shown is available at:
http://www.dot.state.mn.us/its/design.html.

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