Indo-HCM Snippets - LowRes

Indian
Highway Capacity Manual (Indo-HCM)

Indian Highway Capacity Manual
(Indo-HCM)
Sponsored by
Council of Scienti ic and Industrial Research (CSIR), New Delhi
2012-2017
About the Manual

The need for an Indian Highway Capacity Manual (referred as Indo – HCM) has been felt for a long
time by researchers, policy makers and planners in the country. Hence a maiden attempt was made by
CSIR - Central Road Research Institute (CRRI), New Delhi to network with academic institutes (by
including IITs / NITs/ Central/ State Universities) on the lines of HCM (2010) of USA. This mission mode
project led by CSIR - CRRI was completed on time with regular monitoring at different levels to achieve
the desired quality which has showcased once again the technical prowess and management expertise
of CSIR - CRRI in handling large size projects.
Chapter-1 presents a bird's eye view of the structure of the manual and de inition of generic
terminologies related to traf ic engineering and planning. Each of the subsequent nine chapters deals
with the procedure for the estimation of capacity and Level of Service (LOS) through a series of steps and
culminates with typical illustrative examples. These examples are expected to be of immense use for the
analysts in understanding the essence of the Indo - HCM towards the estimation of capacity and Level of
Service (LOS) of various types of roads (both midblock sections and various types of intersections) and
different forms of urban pedestrian facilities dealt in this manual. Moreover, this manual would provide
a much-needed reliable source to update the IRC documents and standards for evolving new guidelines
to address the missing links. Further, it is expected that this document can serve the society as a basic
guide for the practicing engineers and decision makers towards capacity augmentation of various types
of road and pedestrian facilities in India.
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Indian Highway Capacity Manual (Indo-HCM)
Indian Highway Capacity Manual
(Indo-HCM)
Sponsored by
Council of Scienti ic and Industrial Research (CSIR), New Delhi
2012-2017
About the Manual

The need for an Indian Highway Capacity Manual (referred as Indo – HCM) has been felt for a long
time by researchers, policy makers and planners in the country. Hence a maiden attempt was made by
CSIR - Central Road Research Institute (CRRI), New Delhi to network with academic institutes (by
including IITs / NITs/ Central/ State Universities) on the lines of HCM (2010) of USA. This mission mode
project led by CSIR - CRRI was completed on time with regular monitoring at different levels to achieve
the desired quality which has showcased once again the technical prowess and management expertise
of CSIR - CRRI in handling large size projects.
Chapter-1 presents a bird's eye view of the structure of the manual and de inition of generic
terminologies related to traf ic engineering and planning. Each of the subsequent nine chapters deals
with the procedure for the estimation of capacity and Level of Service (LOS) through a series of steps and
culminates with typical illustrative examples. These examples are expected to be of immense use for the
analysts in understanding the essence of the Indo - HCM towards the estimation of capacity and Level of
Service (LOS) of various types of roads (both midblock sections and various types of intersections) and
different forms of urban pedestrian facilities dealt in this manual. Moreover, this manual would provide
a much-needed reliable source to update the IRC documents and standards for evolving new guidelines
to address the missing links. Further, it is expected that this document can serve the society as a basic
guide for the practicing engineers and decision makers towards capacity augmentation of various types
of road and pedestrian facilities in India.
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IR INDIA
Mathura Road, New Delhi-110025 CSIR - CENTRAL ROAD RESEARCH INSTITUTE
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December, CS
http://www.crridom.gov.in Price: ` 3500 2017
IR INDIA
NEW DELHI-110025
in association with
Indian Institute of Technology (IIT) Roorkee, Roorkee
Indian Institute of Technology (IIT) Bombay, Mumbai
Indian Institute of Technology (IIT) Guwahati, Guwahati
School of Planning and Architecture (SPA), New Delhi
Sardar Vallabhai Patel National Institute of Technology (SVNIT), Surat
Indian Institute of Engineering and Sciences University (IIEST), Shibpur
Anna University (AU), Chennai

Indian Highway Capacity Manual (Indo - HCM)
STUDY TEAM
Prof. Satish Chandra
Director, CSIR - CRRI
Dr. S. Gangopadhyay
Director, CSIR - CRRI: (Till 30.11.2015)
Dr. S. Velmurugan, Senior Principal Scientist and Champion
Dr. Kayitha Ravinder, Principal Scientist and Co Champion
Chapter
Work Package Leaders Regional Coordinators
Number
Dr. S. Velmurugan,
Chapter -1 —
Senior Principal Scientist
Dr. Ch. Ravisekhar, Principal Scientist and Prof. Satish Chandra, IIT Roorkee (since
Chapter - 2
Dr. J. Nataraju, Principal Scientist 18.1.2016 as Director, CSIR – CRRI)
Chapter - 3 Sh. Ashutosh Arun, Scientist Prof. Sudip Kumar Roy, IIEST, Shibpur
Chapter - 4 Dr. K. Ravinder, Principal Scientist Prof. Gaurang J. Joshi, SVNIT Surat
Prof. K. Gunasekaran,
Chapter - 5 Dr. A. Mohan Rao, Principal Scientist
Anna University, Chennai
Sh. Subhash Chand, Principal Scientist and Prof. K.V. Krishna Rao,
Chapter - 6
Dr. Neelam J. Gupta, Principal Scientist IIT, (Bombay), Mumbai
Sh. Subhash Chand, Principal Scientist and
Chapter -7 Prof. P.K. Sarkar, SPA, New Delhi
Dr. Neelam J. Gupta, Principal Scientist
Prof. Satish Chandra, IIT Roorkee and
Chapter - 8 Dr. Mukti Advani, Senior Scientist
Prof. Akhilesh Maurya, IIT, Guwahati
Dr. Purnima Parida, Prof. Manoranjan Parida,
Chapter - 9
Senior Principal Scientist IIT (Roorkee), Roorkee
Chapter- 10 Dr. Ch. Ravisekhar, Principal Scientist —
Automatic Road Survey System (ARSS) Team: CSIR - CRRI

Sh. K. Sitaramanjaneyulu, Senior Principal Scientist, Pavement Evaluation Division (PED)
Sh. Pradeep Kumar, Principal Scientist, PED
Sh. Subhash, Technician, PED
Sh. Sunil Dutt, Technician, PED
Team from Project Monitoring and Evaluation (PME) Division: CSIR - CRRI
Dr. B. Kanaga Durai, Chief Scientist, PME Division and Advisor
Sh. P.V. Pradeep Kumar, Senior Principal Scientist and Head, PME Division
Sh. D. Ravinder, Technical Officer, PME Division
Sh. Anshul Saxena, Technical Assistant, PME Division
Secretarial Assistance
Sh. Daleep Mutreja
Mrs. Krishna Verma
CSIR - Central Road Research Institute, New Delhi Page i

TABLE OF CONTENTS
CHAPTER
TITLE PAGE NUMBER
NUMBER
Study Team i
Foreword v
Acknowledgements vii
Executive Summary ix
1 CHAPTER 1: Basic Concepts and

1 - 1 to 1 - 20
Structure of the Manual
2 CHAPTER 2: Single Lane, Intermediate

Lane and Two Lane Interurban 2 - 1 to 2 - 29
Bidirectional Roads
3 CHAPTER 3: Multilane Divided Interurban

3 - 1 to 3 - 32
Highways
4 CHAPTER 4: Interurban and Urban

4 - 1 to 4 - 34
Expressways
5 CHAPTER 5: Urban Roads 5 - 1 to 5 - 34
6 CHAPTER 6: Signalized Intersections 6 - 1 to 6 - 43
7 CHAPTER 7: Roundabouts 7 - 1 to 7 - 28
8 CHAPTER 8: Unsignalized Intersections 8 - 1 to 8 - 25
9 CHAPTER 9: Pedestrian Facilities 9 - 1 to 9 - 36
10 CHAPTER 10: Travel Time Reliability as a

Performance Measure for Interurban and 10 - 1 to 10 - 17
Urban Corridors
CSIR - Central Road Research Institute, New Delhi Page iii

FOREWORD
The need for an Indian Highway Capacity Manual has been felt for a long time by researchers,
policy makers and planners in the country. It was emphasized by the Government of India also in 2012
when the then Planning Commission expressed the immediate need for initiating a comprehensive
research study focusing on scientific estimation of the roadway capacity in India in their Eleventh
Five Year Plan 2007-12 document. Accordingly, the Council of Scientific and Industrial Research (CSIR)
sponsored a research project entitled “Indian Highway Capacity Manual” (referred as ‘Indo-HCM’
in this manual) to CSIR - CRRI in 2012 in the form of mission mode project.
The development of Indo - HCM was not an easy task considering the vast size of the country
and variety of roads and traffic mix. Therefore, CSIR - CRRI identified seven prominent academic
institutes located in different regions in the country to provide technical support for all the Work
Packages as well as to assume the role of Regional Coordinators for one or two work packages
depending upon their expertise. The seven academic institutions identified are Indian Institute of
Technology Roorkee, Indian Institute of Technology Bombay, Mumbai, Indian Institute of Technology,
Guwahati, School of Planning and Architecture, New Delhi, Indian Institute of Engineering and Science
and Technology, Shibpur, (Howrah), Sardar Vallabhai Patel National Institute of Technology, Surat and
Anna University, Chennai. This was the maiden attempt made to network with such a large number
of academic institutes on the lines of HCM of USA. This mission mode project led by CSIR - CRRI was
completed on time with regular monitoring at different levels to achieve the desired quality which has
showcased once again the technical prowess and management expertise of CSIR - CRRI in handling
large size projects. Transportation and Highway professionals can now follow the realistic capacity
values evolved in this manual while undertaking the projects of evaluation of existing road facility or
planning of any new road facility. Each chapter deals with the procedure for the estimation of capacity
and Level of Service (LOS) through a series of steps and culminates with typical illustrative examples.
It is expected that this document can serve the society as a basic guide for the practicing engineers
and decision makers towards capacity augmentation of various types of road and pedestrian facilities
in India.
18.12.2017 (Satish Chandra)

Director, CSIR – CRRI
CSIR - Central Road Research Institute, New Delhi Page v

ACKNOWLEDGEMENTS
The team of CSIR - CRRI would like to place on records its profound gratitude to Council of
Scientific and Industrial Research (CSIR), New Delhi for sponsoring this long-awaited research study.
Further, the CSIR - CRRI led team extends its gratitude to the experts who served as Session Chairs
during the review meetings for extending their immense technical help. Largely, their presence has
helped to monitor the progress achieved in each of the Work Packages (which is rechristened as Chapters
in the manual) during various national level workshops and Task Force Committee (TFC) meetings.
Champion and Co-Champion of Indo-HCM project conducted these meetings in close coordination
with the identified faculty from reputed academic institutes. The faculties representing the respective
institutes have been assigned the role of Regional Coordinators (RCs) cum Local Organizing Secretary
(LOC) for the conduct of the national workshops and TFC meetings. The first workshop in the above
series was conducted in January, 2013 titled, ‘Methodology for Indian Highway Capacity Manual’
(MIHCaM). This was followed by yearly review workshops (3 numbers) conducted in March, 2014,
February, 2015 and March, 2016 titled, ‘RIHCaM-2014’, ‘RIHCaM-2015’, and ‘RIHCaM-2016’ i.e.
‘Review workshop of Indian Highway Capacity Manual’.
During each of the above workshops, the identified experts in the capacity of Session Chairs
have made invaluable contributions. Their contributions encompassed critical appraisal of the
incremental progress made by the Work Package (WP) Leaders / members of CSIR - CRRI as well as
by the seven Regional Coordinators (RCs) by highlighting shortfalls (if any) in the WPs and thereby
necessary course corrections have been done by the concerned team(s). Moreover, a total of nine Task
Force Committee (TFC) meetings chaired by Director, CSIR - CRRI was also convened by Champion
and Co-Champion during the course of the Indo - HCM Project which comprised of WP Leaders from
CSIR - CRRI and RCs serving as principle members. The above workshops and TFC meetings were
conducted by various RCs. The RCs who conducted the above include SVNIT, (Surat), Anna University,
(Chennai), IIT (Guwahati), IIEST (Shibpur), IIT Bombay, Mumbai and IIT Roorkee, Roorkee. Basically,
the above national workshops as well as the deliberations during the TFC meetings the concerned
teams to gear up themselves for the finalization of the chapters dealt by them and facilitated in
streamlining each of the chapters leading to the development of indigenous manual for Indian traffic
conditions.
Eventually, the above streamlined review process culminated with the 2-day national level
dissemination workshop organized by CSIR - CRRI in their premises on 20th and 21st February,
2017 which is again engineered by Champion and Co Champion of Indo - HCM Project. During this
dissemination workshop, an executive summary of the manual was published by the CSIR - CRRI led
team with each of the RCs and Work Package Leaders from CSIR - CRRI presenting the salient findings
included in various chapters of the manual. The issues raised by the Session Chairs and the 150 odd
invited delegates during the Workshop have been appropriately incorporated in the present manual.
The experts who have extended immense contributions during the above national level workshops in
the capacity of Session Chairs are:
1. Prof. M.R. Madhav, Chairman, Research Council, CSIR - CRRI, New Delhi; Prof. Madhav showered
immense praise on the modus operandi followed by CSIR - CRRI team led by Champion / Co-
Champion for project execution in a couple of Research Council meetings convened at CSIR -
CRRI as well as in the RIHCaMs.
2. (Late) Dr. L.R. Kadiyali; Dr. Kadiyali was the author of famous book on ‘Traffic Engineering and
Transportation Planning’ printed by Khanna Publishers. The support extended by him to the
team is fondly remembered.
3. Dr. S. Gangopadhyay, Former Director, CSIR - CRRI; He gave his contribution initially as Director
till 30.11.2015 and subsequently as Session Chair in RIHCAMs. Moreover, Dr. Gangopadhyay
CSIR - Central Road Research Institute, New Delhi Page vii

played a pivotal role in convincing the then Director General, CSIR, Prof. S.K. Brahmachari
to award this project to CSIR - CRRI. Though the project was approved for funding later by CSIR
due to his above efforts, Dr.S. Gangopadhyay asked the Champion to organize a Kick-off Meeting
at CSIR - CRRI (sourcing from Laboratory Reserve of CRRI even before the award of the research
study) on 21.09.2012 by inviting all the involved institutes to discuss the modus operandi. This
contribution is placed on records.
4. Prof. Partha Chakroborty, IIT, Kanpur.
5. Dr. T.S. Reddy, Scientist-G (Retired), CSIR - CRRI and Consultant, M/s. Lea Associates Limited.
6. Prof. V. Thamizh Arasan, IIT, Madras, Chennai (Retired) and Vice Chancellor, Vels University,
Chennai.
7. Prof. P.K .Sikdar, IIT, Bombay, Mumbai (Retired) and President (Traffic and Transportation),
M/s. ICT Private. Limited, New Delhi.
8. Prof. A. Veeraragavan, Department of Civil Engineering, IIT, (Madras), Chennai.
9. Prof. B .K. Katti, SVNIT, Surat, (Retired).
10. Sh. D. Sanyal, Managing Director, M/s. CRAPHTS Consultants (I) Pvt. Ltd. Faridabad, Haryana.
The encouraging words of appreciation remarking on the modus operandi followed for the
Indo - HCM execution by the then Chairman, Research Council (RC) of CSIR - CRRI namely, Prof.
M.R. Madhav, IIT, Kanpur (Retd.) during the course of national level workshops and RC meetings is
gratefully acknowledged.
The study outputs derived from the dissertation works of more than a dozen Doctoral Students
and about 36 Masters students (which included Masters Dissertation as well as Internship program
outputs) as well as Project Fellows / Assistants (their names given in the respective chapters) have
been appropriately incorporated in the manual and hence all their contributions is gratefully
acknowledged.
During this 5-year journey of Indo - HCM project, many Scientists and Technical Staff working
in the Traffic Engineering and Transportation Area (TTP) and other support divisions of CSIR - CRRI
have rendered all types of technical and logistic assistance. This included the present serving staff of
CSIR - CRRI namely, Dr. Anuradha Shukla, Dr. S. Padma (for serving as an excellent anchor during
the dissemination workshop at CSIR - CRRI), Mr. Vivek Dubey, Mr. Mariappan, Mr. S. Kannan, Mr.
Satyabir Singh, Mr. Ambrish Saurikhia and Ms. Nidhi Agarwal as well as some of the retired
staff namely, Mr. S.K. Ummat, Mr. B.M. Sharma and Mr. T.K. Amla. Similarly, the logistic assistance
rendered by the staff of Civil and Electrical Sections of CSIR - CRRI (especially, Mr. Gautam Pande)
during the conduct of Workshops and TFC meetings at the Council Hall of CSIR - CRRI are placed on
records. Further, the contributions rendered by more than 50 staff engaged on daily basis during the
traffic data collection, data collation and analysis phase of the Indo - HCM project is acknowledged.
The spouses and families of CSIR - CRRI Work Packages (WP) Leaders as well as Regional
Coordinators (RCs) had to bear the brunt of the scientists and faculty burning the midnight oil to
complete the project in record time and hence many sacrifices that have been made by their family
members is fondly remembered at this hour.
Last but not the least, the team of CSIR - CRRI would like to place on records their gratitude to
Sh. D.P. Gupta, Former Director General, Ministry of Road Transport and Highways (MoRT&H) for
rendering his essential technical inputs and effecting many essential editorial corrections in the final
report prepared by the teams. His inputs have helped in improving the readability of the manual to a
great extent.
- Team CRRI and Regional Coordinator led by Director, CSIR - CRRI,
Champion, (Indo - HCM) and Co-Champion (Indo - HCM)
CSIR - Central Road Research Institute, New Delhi Page viii

EXECUTIVE SUMMARY
INTRODUCTION
The main hypothesis behind conceiving this project was that Indian traffic characteristics
are fundamentally different from those in the developed countries and even the driver behaviour
is vastly different from even the developing economies like China, Taiwan, Malaysia and Indonesia.
Consequently, the development of an indigenous manual was undertaken on priority in the form of
a mission mode project by considering the various categories of roads like Expressways, National
Highways (NHs), State Highways (SHs), Major District Roads (MDRs), Other District Roads (ODRs)
and Urban Roads (UR) as well as various forms of pedestrian facilities on urban roads. The project
was approved in October, 2012 for funding by CSIR under the Inter Agency Project (IAP) category
of CSIR through Planning Commission grants. The principal goal of this research is to study the
nationwide characteristics of road traffic and to develop a manual for determining the capacity and
Level of Service (LOS) for varying types of interurban roads and urban roads separately by including
controlled intersections i.e. signals and roundabouts and uncontrolled intersections coupled with
addressing the capacity and Level of Service (LOS) of urban pedestrian facilities. To accomplish the
stated goal, the project is aimed at analyzing the characteristics of the heterogeneous traffic flow
and identifies appropriate distributions of the various variables influencing the traffic stream and
pedestrians’ characteristics by examining the traffic flow characteristics through extensive field data
collection and analysis. This summary highlights the maiden attempt undertaken by CSIR - CRRI at
the national level to develop an indigenous manual addressing the traffic heterogeneity prevalent
on Indian roads. The report has been published by CSIR - CRRI with its title, “Indian Highway
Capacity Manual (henceforth referred as ‘Indo-HCM’). This project was executed by CSIR - CRRI
in coordination with reputed academic institutes in the country which included Indian Institute of
Technology (Roorkee) Roorkee, Indian Institute of Technology, (Bombay), Mumbai, Indian Institute of
Technology, (Guwahati), Guwahati, School of Planning and Architecture, New Delhi, Sardar Vallabhai
Patel National Institute of Technology, Surat, Indian Institute of Engineering and Sciences University
(IIEST), Shibpur and Anna University, Chennai. The project was executed by Champion and Co-
Champion in close coordination with Work Package Leaders as well as the faculty from the above
reputed academic institutes have been assigned the role of Regional Coordinators (RCs).
STRUCTURE OF INDO - HCM

The findings of the Indo-HCM project is presented under the following ten chapters in this
manual:
• Chapter 1: Basic Concepts and Structure of the Manual
• Chapter 2: Two Lane, Intermediate and Single Lane Roads
• Chapter 3: Multilane Interurban Highways
• Chapter 4: Inter urban and Urban Expressways
• Chapter 5: Urban Roads
• Chapter 6: Signal Controlled Intersections
• Chapter 7: Roundabouts
• Chapter 8: Uncontrolled Intersections
• Chapter 9: Pedestrian Facility
• Chapter 10: Reliability as a Performance Measure for Inter-urban and Urban Arterials
CSIR - Central Road Research Institute, New Delhi Page ix

As the title suggests, Chapter -1 presents an overview of the structure of the report, definition
of generic terminologies related to Traffic Engineering and Planning followed by an overview of the
types of road and pedestrian facilities considered and also vehicle types and other salient features.
Chapters 2 to 8 focus on varying types of road facilities. Pedestrian facility is dealt in Chapter 9
and Chapter 10 focuses exclusively on Travel Time Reliability of urban and interurban corridors.
Illustrative examples and a list of references are included in each chapter.
NEW CONCEPTS IN INDO-HCM

The new concepts evolved or published works of the team have been included in various
chapters of Indo-HCM are breifly highlighted in the succeeding sections.
Capacity and Level of Service of Mid Block Sections

Chapters 2 to 5 discuss the capacity and level of service analysis on interurban and urban roads
with varying typologies. The PCU value of a vehicle type is found to be sensitive to traffic and roadway
conditions. Hence, a single set of PCU could not be recommended for all types of traffic conditions.
A small change in either traffic volume or traffic composition may change PCU factors substantially,
especially for large size vehicles. Hence the PCU for a given vehicle type is estimated using Equation 1.
Vc/V1
PCUi = ———— Equation 1
Ac/Ai
Where,
Vc and Vi are speed of standard car and vehicle type ‘i’ respectively and
Ac and Ai are their projected rectangular area on the road.
Moreover, it was felt that the dynamic PCUs evolved in this manual in the case of midblock road
sections are not sufficient to understand the complete variation in PCU for a vehicle type. Therefore,
a new concept of Stream Equivalency Factor (Se) is introduced in this manual to take care of dynamic
nature of PCU. Stream Equivalency Factor (Se) is defined as the ratio of flow in PCUs per hour to the
flow in vehicles per hour which is given in Equation 2.
Flow in PCU/hour
Se = ———————————— Equation 2
Flow in vehicles/hour
The factor Se is an overall equivalency factor for the entire traffic stream. It is correlated with
traffic volume and its composition on the road.
Capacity of a two-lane road is influenced by the road conditions and drivers’ behaviour. Hence a
linear relation as typically presented in Equation 3 is observed to exist between capacity and operating
speed () of standard cars plying on varying typologies of interurban and urban roads. In this context,
the operating speed on a road is taken as the 85th percentile of free flow speeds of standard cars. A
vehicle travelling with headway 8 seconds or more is considered as free flowing.
Base Capacity = A + B * VOS Equation 3
Where,
VOS = Operating Speed of Standard Cars, km/hr
In general, it is an established fact that the term ‘capacity’ and ‘LOS’ will have a close relationship.
Capacity refers to the quantitative measure of road section and LOS represents the qualitative measure
of the road section. Speed has been considered as the principal factor affecting the LOS of an urban
road segment under ideal conditions. Stream speed has been considered as the basic parameter for
the estimation of LOS in the present study and hence clustering technique has been used for grouping
CSIR - Central Road Research Institute, New Delhi Page x

of the speed data. The suggested LOS for the range of stream speed, Volume - Capacity Ratio and
percentage of free flow speed is subsequently presented.
Several new measures are suggested in the manual to define LOS on undivided and divided road
sections. For example, on a two-lane road, level of service is defined in terms of number of followers.
A vehicle is taken in the following state if it moves with a gap less than or equal to critical gap with
lead vehicle. The critical gap (CG) is related with traffic volume by Equation 4. The critical gap value is
expected to vary with the traffic volume on the road and hence the relationship established between
the two for two lane two way roads is presented in the above equation.
CG = 74.8 * Q–0.45 Equation 4
Where,
Q = Two-way traffic volume, (in veh/h)
CG = Critical Gap value, (in seconds)
Critical gap value decreases with the increase in traffic volume on the road. Eventually, the
number of followers as part of the road capacity (NFPC) is found to be related with two-way two-lane
traffic volume as presented in Equation 5.
NF = 1.1742 * Q0.9306 Equation 5
Where,
Q = Two-way traffic volume, PCU/h
NF = Number of followers, PCU/h
Further, LOS parameter is taken as the number of followers as part of the road capacity (NFPC).
Therefore, NF in the above equation is considered in PCU/hour to avoid any mismatch of units while
calculating NFPC.
Saturation Flow and Capacity of Signalized Intersections

In the case of signalized intersections given in Chapter 6, the analyst has the option of measuring
the saturation flow in the field by following the prescribed procedure or estimating the saturation flow
using the model given in this manual. PCUs for converting the observed vehicle types into equivalent
passenger cars are furnished in this chapter. The estimated base saturation flow can be adjusted by
applying adjustment factors to get the saturation flow under prevailing geometric, traffic and control
conditions. The capacity of each approach and that of the overall intersection can then be calculated
based on the saturation flow, effective green time and the cycle time. Control delay is prescribed
as the measure of effectiveness for determining the level of service of signalized intersections. The
stopped delay measured in the field is converted into control delay using the prescribed conversion
factors.
Critical Gap and Capacity of Roundabouts

In the case of roundabouts presented in Chapter 7, the critical gaps are estimated based on
the technique related to the accepted and maximum rejected gaps using Root Mean Square Method.
Root Mean Square (RMS) is an analytical model where the minimization of square root of the mean
squared deviation of predicted value from a given baseline or fit gives the absolute measure fit.
Critical gap estimation requires information about the accepted gap and the maximum rejected gap
for each driver. RMS model minimizes the square root of the mean squared deviation of Rejected gap
value Ri and Accepted gap value Ai from expected critical gap value Tc to give the average critical gap
value. The function depicting the estimation of critical gap has been written as given in Equation 6.
CSIR - Central Road Research Institute, New Delhi Page xi

 n ( Ai − Tc ) 2 + (Tc − Ri ) 2 
Min ∑  Equation 6
 i =1 2 
Where,
Ai = Accepted gap of the ith entering vehicle (seconds),
Ri = Highest Rejected gap of the ith entering vehicle (seconds) and
Tc = Critical gap value (seconds).
Critical Gap and Capacity of Unsignalized Intersections

In the case of Unsignalized intersections presented in Chapter 8, since the gap acceptance theory
is primarily dependent on critical gap value, a method termed as Occupancy Time Method (OTM) has
been conceived for the calculation of critical gaps. Unlike the other methods of critical gap estimation,
OTM also incorporates actual driver behaviour observed on unsignalized intersections largely. As
such, OTM accounts for the actual clearing pattern of the conflict area and the traffic interaction that
occurs within this region. Thereafter, the capacity for various movements observed at an unsignalized
intersection is carried out through a series of steps as detailed out in this chapter.
Capacity of Pedestrian Facilities

In the case of pedestrian facilities in urban areas presented in Chapter 9, capacity and LOS
of Footpaths, Stairways and Foot Over Bridges (FOBs) have been presented in this chapter. For the
purpose of the above estimation, a simplified body ellipse of 0.35 m by 0.51 m (total area 0.18 m2)
is used as the basic space for a pedestrian in this chapter. This represents the practical minimum
space for standing pedestrians. Eventually, the required space for various forms of pedestrian facility
in Indian context has been determined in this chapter. Thereafter, macroscopic modelling approach
to build the empirical equation aimed at quantifying the flow of pedestrians and the capacity of
various forms of pedestrian facilities. The relationship among density, speed and directional flow for
pedestrians is similar to that for vehicular traffic streams and the same is presented in Equation 7.
Qp = Vp × Kp Equation 7
Where,
Qp = Unit flow rate (ped/min/m)
Vp = Pedestrian speed (m/min), and
Kp = Pedestrian density (ped/m²)
Further, Pedestrian Level of Service (PLOS) is a measure for assessing the operating condition
of facilities in a quantitative manner. It denotes the level of comfort offered by the type of facility
to pedestrians while using the facility. Pedestrian Level of Service (PLOS) is defined based on
fundamental pedestrian flow parameters for five different land uses as test sections considered in
this chapter encompassed varied land uses. Eventually, 6 types of LOS are defined starting from LOS
A to LOS F for the following types of pedestrian facilities namely, footpaths, stairways and foot over
bridge based on the varying types of type of land uses. On the other hand, LOS for Crosswalks is
evolved based on pedestrian delay observed at the study locations. In addition to the above, Quality
of Service (QOS) of the footpaths (in terms of Walkability Index) has been captured through a detailed
questionnaire survey by understanding the perception of the pedestrians. Thus, the Walkability Index
(WI) is calculated using Equation 8:
Walkability Index: QOS = Equation 8
CSIR - Central Road Research Institute, New Delhi Page xii

Where,
Ai: Importance weight for physical and user characteristics
Bi: Satisfaction rating for physical and user characteristics
Travel Time Reliability as a Performance Measure for Interurban and

Urban Corridors
Travel time reliability is considered as a useful tool for the road users as well as for the public
transit system planners. As such, Travel Time Reliability concept was introduced by Asakusa by
considering selected network of roads in Japan and the same has found a found a place in the fifth
edition of HCM (2010) published by Transportation Research Board. It is defined as the probability
that the trip between a given Origin - Destination (O-D) pair can be made with a certain degree of
reliability under varying time periods of the day and specified Level of Service. This measurement
is found to be useful while evaluating network performance under normal daily flow variations and
various uncertainties. Considering the above, methodology for the travel time reliability analysis
for uninterrupted and interrupted urban arterial roads and interurban highway corridor has been
conceived in this chapter for the Indian traffic conditions based on the estimation of travel time
reliability measures and development of LOS based on reliability measures. The present chapter
provides the methodology to deploy travel time reliability as a performance measure of urban
arterial corridors which encompasses only the uninterrupted and interrupted flow corridors as
well as interurban corridors. It also provides a procedure to determine the Level of Service (LOS) of
the candidate test sections considered in this study. In the case of uninterrupted in urban corridor,
the length of the selected uninterrupted section ranges from 2.5 to 3 km. However, in the case of
interrupted flow in urban corridor, the length of the interrupted section is around 1.5 km to 3 km
whereas the location of controlled intersection is at least 500 m away from the start and the end
points of the study section. At the same time, in the case of interurban uninterrupted corridor, since
such a test section invariably exists beyond the urban periphery on the National Highways or State
Highways connecting major cities, the length of the test section considered for analysis is at least 3
km. Such road sections should not have influence due to the aforesaid urban conditions except for
catering to insignificant proportion of Left-in and Left-out traffic from minor road. The assessment of
operational performance for the above types of road environs has been done for both public transport
and private vehicles. In this regard, LOS based Travel Time Reliability for cars, two wheelers, Public
Transit System (both conventional and BRTS corridor) has been framed in this chapter.
Innovative Process of Manual Development

This project of development of Indo-HCM itself is innovative as there has not been any such
attempt in the past in India. The development of Indo - HCM was not an easy task considering the
vast size of the country and variety of roads and the heterogeneous traffic mix. Therefore, CSIR -
CRRI identified seven prominent academic institutes located in different regions in the country
to provide technical support for all the Work Packages as well as to assume the role of Regional
Coordinators (RC) for one or two work packages depending upon their expertise. As mentioned
earlier, the seven academic institutions identified are Indian Institute of Technology Roorkee,
Indian Institute of Technology Bombay, Mumbai, Indian Institute of Technology, Guwahati, School of
Planning and Architecture, New Delhi, Indian Institute of Engineering and Science and Technology,
Shibpur, Howrah, Sardar Vallabhai Patel National Institute of Technology, Surat and Anna University,
Chennai. The methodology for collection and analysis of traffic data was finalized in the common
meeting of Regional Coordinators. Each RC collected traffic flow data on various types of facilities in
the respective regions of the country and provided to the respective Work Package (WP) in charge for
CSIR - Central Road Research Institute, New Delhi Page xiii

analysis. The identified institutes as well as Work Package leaders from CSIR – CRRI performed traffic
data collection at pan-India covering all types of road network (Expressways, National Highways. State
Highways, Major District Roads and Other District Roads) including various forms of urban pedestrian
facilities.
Prof. Satish Chandra, Director, CSIR – CRRI spearheaded the entire Indo - HCM team with
the project execution performed under the leadership of Dr. S. Velmurugan, Champion and aided
by Dr. K. Ravinder, Co-Champion. As mentioned earlier, this was the maiden attempt by CSIR - CRRI
to network with such a large number of academic institutes on the lines of HCM (2010) of USA. The
project was completed on time with regular monitoring at different levels to achieve the desired
quality. This mission mode project led by CSIR - CRRI was completed in time with regular monitoring
at different levels to achieve the desired quality, which has once again displayed the technical prowess
and management expertise of CSIR - CRRI in handling large size projects. Largely, the various national
level workshops and task force committee meetings conducted by Champion and Co-Champion of
Indo - HCM Project in close coordination with faculty from reputed academic institutes who have
been assigned the role of Regional Coordinators (RCs) cum Local Organizing Secretary (LOC) for the
conduct of the national workshop has helped this cause. The first workshop in the above series was
conducted in January, 2013; it was followed by yearly review workshops (three numbers) conducted
in March, 2014, February, 2015 and March, 2016 in different academic institutes involved in this
study.
During each of the above workshops, the identified experts in the capacity of Session Chairs were
invited for critical monitoring of the incremental progress made by the Work Package (WP) Leaders
/ members of CSIR - CRRI. All the suggestions of the learned experts were considered positively and
the concerned teams in their chapters did necessary course corrections. Moreover, a total of nine
Task Force Committee (TFC) meetings chaired by Director, CSIR - CRRI were also convened by the
Champion and the Co-Champion during the course of the Indo - HCM Project which comprised of
WP Leaders from CSIR - CRRI and RCs serving as principle members. The above national workshops
as well as the deliberations during the TFC meetings aided the concerned teams to gear up for
the finalization of the chapters dealt by them and facilitated in streamlining each of the chapters
leading to the development of indigenous manual for India. Eventually, the above streamlined review
process culminated with a 2-day national level dissemination workshop organized by CSIR - CRRI
in its premises on 20th and 21st February, 2017 which was again engineered by Champion and Co
Champion of Indo - HCM Project. During the above workshop, an executive summary of the manual
was published by the CSIR - CRRI led team with each of the RCs and Work Package Leaders from
CSIR - CRRI presenting salient findings included in various chapters of the manual. The issues raised
by each of the Session Chairs and the 150 odd invited delegates during the Workshop have been
appropriately incorporated in the present manual. During the execution of the project, several new
concepts were evolved considering the unique traffic behavior on Indian roads. A few of them are
listed below:
• Modus Operandi followed for the execution of Indo - HCM is itself innovative as there has not
been any similar attempt made in the past in the country.
• Dynamic Passenger Car Unit (DPCU) based on Area and Speed of a vehicle.
• Development of Stream equivalency factor for readymade estimation of capacity
• Relationship between Operating Speed and Capacity that can be used to estimate the capacity
of any given road provided Free Flow Speed (FFS) of a minimum sample size of 200 standard
cars be collected for any type of road.
• Estimation of Level of Service on Interurban Undivided carriageways through the Number of
Followers per Capacity (NFPC).
CSIR - Central Road Research Institute, New Delhi Page xiv

• Level of Service (LOS) estimation for Signalized Intersection through User Perception Surveys
• Gap acceptance model for analysis of roundabouts
• Occupancy time method for estimation of critical gap, estimation of capacity (of movements)
and Level of Service of unsignalized intersections and
• Concept of travel time reliability for interurban and urban arterial roads.
Societal Benefits
Engineers / Planners / Bureaucrats can look to follow the realistic capacity values evolved in
this manual during the planning of new facilities instead of using either the obsolete values available
in the relevant Indian Roads Congress (IRC) documents or directly adopting the values given in US-
HCM (2010) or other manuals, which are not directly applicable to Indian road scenario.
It is expected that the manual would serve as a basic guide for the practicing engineers and
decision makers towards capacity augmentation of various types of roads, (both at mid-block sections
and intersections of varied typologies) as well as pedestrian facilities. Efforts are already in place from
the scientists of CSIR - CRRI as well as Regional Coordinators (RCs) associated with the various Indian
Roads Congress (IRC) technical committees to incorporate the study findings from this manual in the
appropriate documents of IRC for their revision. In this context, the following guidelines of IRC need
either immediate revision or formulation of new guidelines based on the above results derived in the
Indo - HCM project and efforts are in place for the same as mentioned above:
• IRC:64 (1990) Guidelines for Capacity of Rural Roads in Plain Areas
• IRC:106 (1990) Guidelines for Capacity of Urban Roads in Plain Areas
• IRC:65 (1976) Recommended Practice for Roundabouts
• IRC 93 (1985) Guidelines on Design and Installation of Road Traffic Signals
• IRC:103 (2012) Guidelines for Pedestrian Facilities
• New Capacity Guidelines for Unsignalized Intersections
• New Guidelines for Travel Time Reliability on Urban and Interurban Corridors.
CSIR - Central Road Research Institute, New Delhi Page xv

Chapter 1:
Basic Concepts and
Structure of the Manual
Basic Concepts and Structure of the Manual
TABLE OF CONTENTS
Section Page
Title
Number Number
Study Team i
List of Figures iv
List of Tables iv
1.1 PREAMBLE 1
1.2 STUDY OBJECTIVES AND SCOPE 1
1.3 MODUS OPERANDI 1
1.4 PURPOSE OF INDO-HCM 2
1.5 DEFINITION OF TERMINOLOGIES 2
1.5.1 Road Facility Based Terminologies 2
1.5.2 Pedestrian Facility Based Terminologies 8
1.6 TRAFFIC FLOW AND CAPACITY 9
1.7 VEHICLE TYPES 10
1.8 STRUCTURE OF THE MANUAL 14
Chapter 2: Single lane, Intermediate and Two lane Interurban
1.8.1 14
Bidirectional Roads
1.8.2 Chapter 3: Multilane Interurban Divided Highways 15
1.8.3 Chapter 4: Interurban and Urban Expressways 15
1.8.4 Chapter 5: Urban Roads 15
1.8.5 Chapter 6: Signalized Intersections 15
1.8.6 Chapter 7: Roundabouts 16
1.8.7 Chapter 8: Unsignalized Intersections 16
1.8.8 Chapter 9: Pedestrian Facilities 16
1.8.9 Chapter 10: Travel Time Reliability 17
1.9 PROCESS OF DEVELOPMENT AND SOCIETAL BENEFITS OF THE MANUAL 17
1.9.1 Innovative Process of Manual Development 17
1.9.2 Societal Benefits 19
REFERENCES 20
CSIR - Central Road Research Institute, New Delhi Page 1 - iii

1.1 PREAMBLE
This chapter is the starting point for learning to use the maiden edition of the ‘Indian Highway
Capacity Manual’. The chapter covers the purpose, objectives, methodology adopted, proposed use as
well as target users of the manual. It also provides definition of terminologies and a brief on each of
the subsequent chapters of the manual.
The main hypothesis behind conceiving this research project is that traffic characteristics
on Indian roads are fundamentally different from those in the developed economies and even the
driver behaviour is quite different from the developing economies like China, Malaysia and Indonesia.
Several countries have developed their own highway capacity manuals reflecting the traffic pattern
prevalent in their respective countries. Obviously, the capacity manuals from these countries cannot
be transformed for Indian traffic conditions by developing any adjustment factors. Moreover, based on
the communicated views of CSIR – CRRI (in 2010), the immediate need for initiating a comprehensive
research study focusing on scientific estimation of the roadway capacity was aptly emphasized in 2012
by the Planning Commission, Government of India (refer Volume III: Agriculture, Rural Development,
Industry, Services and Physical Infrastructure of the Eleventh Five Year Plan 2007-12 document).
Considering the importance attributed by the Government of India (GoI) on this issue,
it was felt essential to develop an indigenous highway capacity manual by considering the Indian
traffic scenario as this would be of immense use to the engineers, bureaucrats and planners. The
development of such a manual would certainly help policy makers in deciding allocation of budget
for capacity augmentation of roads and enhancing productivity of road transport through increased
Level of Service (LOS).
Accordingly, this research was classified by the Council of Scientific and Industrial Research
(CSIR) under the theme entitled, “Knowledge / Technology space where we do not have expertise
and we would like to achieve”. This CSIR sponsored research study project is entitled as “Indian
Highway Capacity Manual” (henceforth referred to as ‘Indo-HCM’ in this manual). Subsequently,
the development of Indo - HCM was undertaken on priority in the form of a mission mode project by
CSIR – CRRI. In this study, various categories of roads in India like Expressways, National Highways
(NHs), State Highways (SHs), Major District Roads (MDRs), Other District Roads (ODRs) and Urban
Roads (UR), as well as various types of intersections (i.e. Signalized, Roundabout and Unsignalized
Intersections) and pedestrian facilities seen on urban roads in the country have been considered.
1.2 STUDY OBJECTIVES AND SCOPE

The objectives of the Indo-HCM are:
• To study the nationwide road traffic characteristics and
• To bring out a manual for determining the capacity and Level of Service (LOS) for various
categories of interurban and urban roads and intersections as well as roundabouts and also
various forms of pedestrian facilities on urban roads.
In order to accomplish the above stated objectives, the study has addressed analysis of the
heterogeneous traffic flow characteristics under varying environs. In this regard, an attempt has
been made to address the appropriate distribution of the various variables influencing the traffic
stream characteristics on various categories of roads, intersections and pedestrian facilities through
extensive field data collection spread over the country and the associated analysis.
CSIR - Central Road Research Institute, New Delhi Page 1 - 1

1.3 MODUS OPERANDI

The study project was approved in October, 2012 for funding by CSIR under the Inter Agency
Project (IAP) category of CSIR through Planning Commission grants. CSIR - Central Road Research
Institute (CRRI), New Delhi was the nodal research organization. Seven prominent academic institutes
located in different regions in the country were made partners to this project to provide technical
support in all the Work Packages (WPs) and thus assigned the role of Regional Coordinators (RCs) for
one or two WPs depending on their expertise. The academic institutions identified are:
1. Indian Institute of Technology, (Roorkee),
2. Indian Institute of Technology, (Bombay), Mumbai,
3. Indian Institute of Technology, (Guwahati),
4. School of Planning and Architecture, (New Delhi),
5. Indian Institute of Engineering and Science and Technology, Shibpur, (Howrah),
6. Sardar Vallabhai Patel National Institute of Technology, (Surat) and
7. Anna University, (Chennai).
1.4 PURPOSE OF INDO-HCM

Transportation and Highway fraternity can look to follow the realistic capacity values evolved
in this manual while undertaking evaluation of existing road facility or planning of any new road
facility without relying on obsolete or adhoc capacity values as well as procedures given in some of
the Indian Roads Congress (IRC) documents. Moreover, indigenous manual would obviate the need
to direct adoption of the capacity values given in HCM of USA (2010) or manuals of other countries
i.e. Chinese HCM (2005) or Indonesian HCM (1999). It is worthwhile to mention here that the values
given in the above-referred manuals evolved for other countries cannot be translated for Indian
traffic conditions through evolving adjustment factors, as these would not be replicating Indian traffic
scenario. In this regard, this manual is expected to provide a much-needed reliable source to update
the above IRC documents and standards as well in addition to evolving new guidelines to address the
missing links.
1.5 DEFINITION OF TERMINOLOGIES ...

Chapter 2:
Single Lane, Intermediate Lane and
Two Lane Interurban Bidirectional Roads
Single Lane, Intermediate Lane and Two Lane Interurban Roads
TABLE OF CONTENTS
Page
Section
Title
Number
Number
Study Team i
Contributions of Students ii
List of Figures v
List of Tables vi
List of Abbreviations vii
2.1 INTRODUCTION 1
2.2 DEFINITIONS AND TERMINOLOGIES 1
2.3 FUNCTIONAL CHARACTERISTICS 3
2.3.1 Two Lane Roads 3
2.3.2 Intermediate Lane Roads 4
2.3.3 Single Lane Roads 4
2.4 BASE CONDITIONS FOR CAPACITY ESTIMATION 4
2.5 SCOPE AND LIMITATION 5
2.6 METHODOLOGY 5
2.6.1 Framework for Capacity Estimation 7
2.7 PASSENGER CAR UNIT VALUES 10
2.8 STREAM EQUIVALENCY FACTOR (Se) 12
2.8.1 Single Lane Roads 13
2.8.2 Intermediate and Two Lane roads 13
2.9 CAPACITY UNDER BASE CONDITIONS 14
2.9.1 Speed - Flow Relationship 14
2.9.2 Base Capacity of Two Lane Roads 15
2.9.3 Base Capacity of Intermediate Lane Roads 15
2.9.4 Base Capacity of Single Lane Roads 16

2.10 ADJUSTMENT FACTORS 16
2.10.1 Adjustment Factor for Carriageway Width 16
2.10.2 Adjustment Factor for Paved Shoulder 17
2.10.3 Adjustment Factor for Directional Split 17
2.10.4 Adjustment Factor for Road Geometry 17
2.10.5 Adjustment Factor for Riding Quality 18
2.11 LEVEL OF SERVICE 19
2.11.1 Number of Followers 21
2.11.2 Identification of the Critical Gap Value 22
2.12 ILLUSTRATIVE PROBLEMS 23
2.12.1 Method of Estimation of Dynamic Passenger Car Unit 23
2.12.2 Determination of Capacity and Level of Service 25
Determination of Capacity and Level of

2.12.3 26
Service of Hilly Roads
REFERENCES 28
SUGGESTED READINGS 28
CSIR - Central Road Research Institute, New Delhi Page 2 - iv

2.1 INTRODUCTION
Interurban highways in India include single lane roads, intermediate lane roads, two lane
roads, multi-lane highways and expressways. Single lane, intermediate lane and two lane roads are
undivided, facilitating two-way movement of traffic, whereas multi-lane highways and expressways
have divided carriageways with two or more lanes in each direction. On the other hand, traffic
operations on undivided roads are vastly different from that on divided highways. Hence, the
capacity and LOS of undivided roads and multilane divided highways have been dealt with separately
in this manual. A substantial proportion of National Highways (NHs) and State Highways (SHs) in
the country are still either two lane or intermediate lane carriageways. Similarly, majority of Major
District Roads (MDRs) are with either two lane or intermediate lane carriageways, while the Other
District Roads (ODRs) and Village Roads (VRs) are generally provided with single lane and only in few
cases with intermediate lane carriageways. Single lane roads have 3.75 m wide carriageways whereas
intermediate lane roads have carriageways between 5.5 m and 6.0 m wide carriageways. The existing
single lane roads are upgraded to intermediate lane roads where funds are not sufficient to widen
from single lane to two lane roads immediately. Traffic operations on two lane or intermediate lane
roads are unique in nature. Lane changing and overtaking manoeuvres are possible only in the face of
oncoming traffic in the opposing lane. The overtaking demand increases while passing opportunities
decline rapidly as the traffic volume increases. Therefore, flow in one direction influences the flow in
the other direction. This problem is more acute in the case of mixed traffic where speed differential
amongst different vehicle types is significant. It increases the desire for overtaking manoeuvres
considerably whereas number of opportunities to overtake is limited. As a result, operating quality
deteriorates as demand flow increases, and operations can become ‘unacceptable’ at a volume, which
is much below the capacity of the road. Single lane roads are normally provided to connect the villages
to district roads and state highways. These are generally feeder roads and experience low traffic
volume. Traffic operations on single lane roads are very much influenced by the condition and width
of the shoulders as vehicles are forced to use them during passing or overtaking operations. This
chapter presents methodologies for the estimation of capacity, operating speeds and Level of Service
of single lane, intermediate lane and two lane roads operating under mixed traffic flow conditions.
2.2 DEFINITIONS AND TERMINOLOGIES

• Annual Average Daily Traffic (AADT): It is the annual average daily traffic when
measurements are taken for the entire 365 days (366 days in case of leap year) of the year and
averaged out.
• Average Daily Traffic (ADT): It is the average daily traffic when measurements are taken for
a few days (less than one year such as monthly or weekly), averaged by the number of days for
which the measurements have been taken.
• Capacity: It is the maximum hourly volume (vehicles per hour) at which vehicles can
reasonably be expected to traverse a point or a uniform section of a lane or roadway under
the prevailing roadway, traffic and control conditions. Following two definitions of capacity
are used in this chapter:
οο Base Capacity: It is the maximum number of vehicles that can pass a given point on
a lane or roadway during one hour, under the most nearly ideal roadway and traffic
conditions, which can possibly be attained.
οο Adjusted Capacity: It is the maximum number of vehicles that can pass a given
point on a lane or roadway during one hour under the prevailing roadway and traffic
conditions. It is obtained by adjusting the base capacity for the roadway and traffic
conditions present at site.

• Composition of Traffic Stream: It is the proportional share of different types of vehicles in

the traffic stream.
• Design Hourly Volume: Design Hourly Volume (DHV) is usually the 30th highest hourly
volume. This hourly volume is exceeded only during 29 hours in a year.
• Design Service Volume (DSV): It is defined as maximum service volume at which vehicles can
reasonably be expected to traverse a point or uniform section of a lane or roadway during one
hour under prevailing roadway, traffic and control conditions while maintaining a designed
Level of Service.
• Design Speed: Design speed depends on the function of the road and terrain classification. It
is the basic parameter, which determines all other geometric design features.
• Free Flow Speed: The mean speed of any vehicle type that can be accommodated under low to
moderate flow rates on a road segment under prevailing roadway and traffic conditions. This
signifies that the Free Flow Speed (FFS) of any given vehicle type, when the traffic flow is such
that the time gap between two consecutive vehicles is more than 8 seconds. Alternatively, FFS
is defined as the maximum speed that can be achieved by any given vehicle type when there
are no interruptions other vehicle types in the traffic for the given road width and terrain
conditions.
• Flow (or Volume): It is the number of vehicles that pass through a given point on a road
during a designated time interval. Since roads have a certain width and the required number
of lanes is accommodated within the available width, flow is always expressed in relation to
the given width i.e. per lane or per direction etc. The time unit selected is one hour.
• Interurban Roads: These roads help in achieving enhanced mobility of traffic between any
adjoining cities or towns. National Highways (NHs), State Highways (SHs), Major District
Roads (MDRs) and Other District Roads (ODRs) all fall under the category of interurban roads.
• Level of Service (LOS): It is defined as a qualitative measure, describing operational
conditions within a traffic stream and their perception by drivers/passengers. LOS definition
generally describes these conditions in terms of factors such as speed and travel time,
freedom to manoeuvre, traffic interruptions, comfort, convenience and safety. Six levels of
service are recognized and these are designated from A to F, with LOS A representing the
best operating condition i.e. free flow and the LOS F, the worst i.e. forced or breakdown flow. A
typical illustration of LOS is given in Section 2.10.
• Number of Followers as Percent of Capacity (NFPC): NFPC is the number of vehicles in
following state on a section of two lanes or intermediate lane road, divided by its capacity. It
is used to define Level of Service on two lane and intermediate lane roads.
• Operating Speed (VOS): It is the 85th percentile of free flow speed of standard passenger cars
(small cars) on a road. A vehicle travelling at headway 8 seconds or more is considered to be
operating under free flow conditions in this manual.
• Passenger Car Unit (PCU): It is the amount of interaction (or impedance) caused by the
vehicle to a traffic stream with respect to a standard passenger car. It is used to convert a
heterogeneous traffic stream into a homogeneous equivalent to express flow and density in
a common unit.
• Peak Hour Flow: Peak rates of flow are related to hourly volumes with peak hour factor. This
factor is defined as the ratio of total hourly volume to the peak rate of flow within the hour.

• Speed: It is the rate of motion of individual vehicles or of traffic stream. It is measured in

metres per second (m/s) or kilometres per hour (km/h). The types of speed measurements
used in traffic engineering are Space Mean Speed and Time Mean Speed.
οο Space Mean Speed (SMS): It is the mean speed of vehicles in a traffic stream at
any instant of time over a certain length of the road. It is the average speed based
on average travel time of vehicles to traverse a known segment of a roadway. It is
generally slightly less than the time mean speed.
οο Time Mean Speed (TMS): It is the mean speed of vehicles observed at a point on the
road over a period. It is the arithmetic mean of spot speeds.
• Terrain Classification: Terrain is classified based on the general cross slope of the country
across the highway alignment. Cross slope is the slope approximately perpendicular to the
road. Terrain is classified as plain, rolling, mountainous and steep as per the criteria given in
Table 2.1.
Table 2.1: Terrain Classification
S.No. Terrain Classification Percent cross slope of the country
1 Plain 0 - 10
2 Rolling 10 - 25
3 Mountainous 25 - 60
4 Steep More than 60
2.3 FUNCTIONAL CHARACTERISTICS
The traffic on Indian roads is composed of slow and fast moving vehicles with substantial
differences in their static and dynamic characteristics including their size and engine power. A wide
range of motorized and non-motorized traffic (NMT) uses the same roadway space resulting in
heterogeneous traffic. The bi-directional traffic on these roads shares the same road space without
physical segregation and occupies any lateral position on the road depending on the availability
of space. The vehicles on these roads rapidly change their positions to obtain a clear view of the
oncoming traffic or to find an opening to perform an overtaking manoeuvre.
2.3.1 Two Lane Roads ...

Chapter 3:
Multilane Divided Interurban Highways
TABLE OF CONTENTS
Section
Title Page Number
Number
Study Team i
Acknowledgements iii
List of Figures vi
List of Tables vi
3.1 INTRODUCTION 1
3.1.1 Scope and Limitation 1
3.4 INPUT DATA 5
3.5 METHODOLOGY 6
3.5.1 Types of Analysis 6
3.5.2 Estimation of Stream Speed 7
3.5.3 Estimation of Operating Speed 7
3.5.4 Estimation of Passenger Car Unit 7
3.5.5 Estimation of Traffic Flows 8
3.5.6 Estimation of Base Capacity 9
3.5.7 Estimation of Adjusted Capacity 9
3.5.8 Estimation of Level of Service 9
3.6 PASSENGER CAR UNIT VALUES 10
3.7 STREAM EQUIVALENCY FACTOR (Se) 13
3.8 BASE CAPACITY ESTIMATION 13
3.9 ADJUSTMENT FACTORS FOR NON BASE CONDITIONS 14
3.9.1 Adjustment for Gradient, Curvature and Roughness 14
3.9.2 Adjustment for Shoulder Width and Median Width 15
3.10 ESTIMATION OF LEVEL OF SERVICE 16

3.11 PROCEDURE FOR ESTIMATION OF CAPACITY AND LOS 18

3.12 ILLUSTRATIVE EXAMPLES 19
3.12.1 Operational Analysis of Four Lane Divided Highway 19
3.12.2 Operational Analysis of Six Lane Divided Carriageway 21
3.12.3 Analysis for Planning of New Multilane Divided Facility 23
3.12.4 Analysis for Widening of Existing Facility 24
REFERENCES 26
ANNEXURE 3A: FIELD DATA COLLECTION 28
3A.1 TRAFFIC DATA COLLECTION AND EXTRACTION 28
3A.2 GEOMETRIC DATA COLLECTION 29
3A.3 PAVEMENT ROUGHNESS DATA COLLECTION 29
3A.4 ENVIRONMENTAL DATA COLLECTION 29
ANNEXURE 3B : RESULTS OF CAPACITY ANALYSIS 30
ANNEXURE 3C : COMPUTATION OF DESIGN HOURLY VOLUMES 32
CSIR - Central Road Research Institute, New Delhi Page 3 - v

3.1 INTRODUCTION
This chapter provides the capacity and Level of Service (LOS) values evolved for vehicular
traffic plying on uninterrupted flow segments of multilane divided interurban highways under mixed
traffic conditions observed in Indian roads. Uninterrupted flow here refers to the flow conditions
observed on roadway segments with no fixed causes of delay or interruption external to the traffic
stream. This implies that the uninterrupted flow facilities referred to in this manual include such
types of multilane divided interurban highway segments which are have median openings that are
spaced at least 1 (one) km apart, and moreover, there are no major access roads connecting to the
highways in those segments. At the same time, minor access roads or driveways joining such highway
segments and catering to a substantially low volume of traffic throughout the day can be tolerated
while defining a facility as an uninterrupted flow facility. Apart from the stated major objective of
specifying the Capacity and LOS values for segments with uninterrupted flow on multilane divided
interurban highways, there are a few other objectives covered in this chapter as well. These are
summarized below:
• Establishin g a relationship between capacity and operating speed for base sections
• Estimation of dynamic Passenger Car Unit (PCU) values for different vehicle-types and Stream
Equivalency Factors (Se) encompassing varying widths of multilane divided interurban
highways
• Estimation of adjustment factors for various road characteristics affecting traffic flows on
multilane divided interurban highways
3.1.1 Scope and Limitation ...

Chapter 4:
Interurban and Urban Expressways
TABLE OF CONTENTS
Section Page
Title
Number Number
Study Team i
List of Figures vi
List of Tables vii
List of Abbreviations viii
4.1 INTRODUCTION 1
4.1.1 Interurban Expressways 1
4.1.2 Urban Expressways 1
4.3 CRITERIA FOR SELECTION OF BASE CONDITION FOR EXPRESSWAYS 4
4.5 METHODOLOGY 6
4.5.1 Input Parameters 7
4.5.2 Calculation of Capacity 7
4.5.3 Traffic Volume 8
4.5.4 Free Flow Speed Distribution 10
4.6 SPEED-FLOW CURVES AND CAPACITY 11
4.6.1 Capacity of Base Sections 11
4.6.2 Effect of Gradient on Six Lane Expressway Segments 12
4.7 DETERMINATION OF LEVEL OF SERVICE (LOS) 13
4.8 APPLICATION 14
4.8.1 Computation of DHV 14
4.8.2 Establishment of Analysis Boundaries 15
4.8.3 Types of Analysis 15


4.9.1 Problem-1 15
4.9.2 Problem-2 17
4.9.3 Problem-3 18
REFERENCES 20
ANNEXURE 4A: DATA COLLECTION STRATEGY 22
ANNEXURE 4B: CAPACITY AND LOS ANALYSIS 23
ANNEXURE 4C: PCU AND STREAM EQUIVALENCY FACTOR ESTIMATION 24
4C.1 Speed-Area Ratio 24
4C.2 Stream Equivalency Factor 24
ANNEXURE 4D: FACTORS AFFECTING FREE FLOW SPEED 26
4D.1 Roadway Width 26
4D.2 Gradient 27
ANNEXURE 4E: DETERMINATION OF TRAFFIC DENSITY 28
Method 1: Fundamental Relationship of
4E.1 28
Traffic Flow Characteristics
Method 2: Density Measurement Using Cumulative Plots
4E.2 28
(Input-Output Method)
4E.3 Method 3: Generalized Edie's Definition 29
ANNEXURE 4F: EXPLANATION ON LEVEL OF SERVICE ESTIMATION 31
ANNEXURE 4G: DDHV VALUES BY VARYING K FACTOR AND D VALUES 34

4.1 INTRODUCTION
4.1.1 Interurban Expressways
An expressway is defined as an arterial highway for motorized traffic having divided
carriageways for high speed travel with full control of access and provided with grade separators
or interchanges at locations of intersections. These are the highest class of roads in the Indian road
network with design speeds ranging from 100 to 120 km per hour in plain terrain. In the case of
interurban expressways connecting cities and towns, vehicle types like motorised two-wheelers and
auto rickshaws are generally be prohibited from entering due to their vulnerability to road crashes.
Because of access control, traffic flow behaviour on expressways is significantly different from other
multilane interurban roads which are faced with mixed traffic conditions prevailing on Indian roads.
Hence, this category of roads is dealt with separately in this manual. Normally, expressways have at
least two lanes in each direction of travel and depending upon the traffic demand it can be divided
carriageways of six-lane, eight-lane or more number of lanes.
4.1.2 Urban Expressways

An urban expressway is a multi-lane road in urban areas with divided carriageway for high
speed travel having full control of access and provided with grade separators and interchanges at
locations of intersections. At the location of entry to exit from the expressway, it is provided with
on-ramp and off-ramp facility respectively. Urban expressways are the highest class of urban roads
in the road network in Indian metropolitan cities with the design speed ranging from 80 to 100 km
per hour in plain terrain. In the case of urban expressways in India, vehicle types like motorised two-
wheelers and motorized three-wheelers are generally permitted to ply despite their vulnerability
to road crashes. This may be attributed to the fact that the travel mode usage in a city may warrant
entry of these vehicles on urban expressways which are very few in the country. Moreover, the entry
and exit points on urban expressways are more frequent compared to interurban expressways. At
the same time, the traffic flow behaviour on urban expressways is significantly different from other
urban roads and streets. An urban expressway shall have at least two lanes in each direction of travel
and depending upon the traffic demand can have six lanes, eight lanes or more in both directions of
travel. The primary difference with respect to interurban expressway is that it serves a particular
urban area, radiating out from the urban centre to serve the surrounding region. It also provides
connectivity for urban traffic to the rural highways or interurban expressways. Urban expressways
can also be elevated or below the ground.
This chapter presents methodologies for the estimation of capacity and LOS values evolved
for vehicular traffic plying on fully access controlled four-lane and six-lane divided interurban
expressways as well as eight lane urban expressways catering to somewhat different traffic conditions
observed on Indian expressways as compared to developed economies.
4.2 DEFINITIONS AND TERMINOLOGIES ...

Chapter 5:
Urban Roads
Urban Roads
TABLE OF CONTENTS
Section Page
Title
Number Number
Study Team i
List of Figures vi
List of Tables vii
5.1 INTRODUCTION 1
5.1.1 Study Objectives 1

5.2.1 Road Parameters 2
5.2.2 Traffic Characteristics 2
5.3 CRITERIA FOR SELECTION OF BASE ROAD SECTION 3
5.4 METHODOLOGY 4
5.4.1 Passenger Car Unit 4
5.4.2 Car as a Single Category 5
5.4.3 Stream Equivalency Factor (Se) 7
5.4.4 Capacity of Base Sections 9
5.4.5 Operating Speed Model 12
5.4.6 Level of Service of Urban Roads 13
5.4.7 Adjustment Factors 16
Example 5.5.1 18
Example 5.5.2 20
Example 5.5.3 21
Example 5.5.4 22

Urban Roads
REFERENCES 24
ANNEXURE 5A: VEHICLE TYPES ON INDIAN URBAN ROADS 26
ANNEXURE 5B: PARAMETERS FOR SELECTION OF BASE TEST SECTIONS OF
27
URBAN ROADS
ANNEXURE 5C: DATA COLLECTION STRATEGY 28
ANNEXURE 5D: DATA EXTRACTION METHOD ADOPTED 29
ANNEXURE 5E: DATA ANALYSIS 30
5E.1 Data Preparation 30
5E.2 PCU Estimation 30
5E.3 Determination of Stream Equivalency Factor (Se) 31
5E.4 Speed - Flow Relationship 31
5E.5 Development of Lane Capacity - Operating Speed Model 32
5E.6 Procedure to Determine Level of Service 32
5E.7 Adjustments for Friction Parameters 33

Urban Roads
5.1 INTRODUCTION
Urban road is the one with a relatively high density of driveway access located in an urban
area and having traffic signals with a minimum spacing of one kilometer. The term ‘Urban Road
Segment’ refers to the length of road with control arrangements at both of its ends, i.e. the upstream
and downstream intersections are controlled intersections. This chapter describes the procedures
for calculation of capacity and performance measures of two lane undivided and four to ten lanes
divided urban roads in India for the given roadway, traffic and environmental conditions.
5.1.1 Study Objectives

• Study and characterization of the basic road traffic flow characteristics such as speed, flow,
density which can eventually lead to the development of Speed-Flow and Speed-Density
relationships for varying widths of urban roads.
• Development of capacity norms and Level of Service (LOS) and for varying road widths of
urban roads including quantification of the friction due to bus bays, on-street parking and
access roads.
5.1.2 Scope and Limitation

Urban roads are generally classified based on the functional characteristics and configuration.
However, as the functional classification varies from city to city. In this context the standard road
width per lane considered is 3.5 m with an additional shyness of 0.25 m provided on either edge of
the road. Hence the typology of roads considered in this manual includes the following:
Divided Roads (in each direction of travel with 0.25 m kerb shyness on either edges of the road):
• 7.5 m road width i.e. Four-lane Divided Road
• 11 m road width i.e. Six-lane Divided Road
• 14.5 m road width i.e. Eight-lane Divided Road
• 18.0 m road width i.e. Ten-lane Divided Road
Undivided Roads: (Road width of 7.0 m plus 0.25 m kerb shyness on either edge)
• 7.5 m road width i.e. Two-lane Undivided Road
The scope of the chapter includes capacity and LOS analysis for the above class of roads only
in this manual. The number of base and non base sections considered across varying road widths
selected in different metropolitan cities of the country namely, Delhi, Mumbai, Kolkata, Chennai,
Jaipur, Chandigarh, Surat, Ahmadabad, Thiruvanthapuram and Guwahati is presented in Table 5.1.
Table 5.1: Number of Test Sections considered across Varying Road Widths
Number of Road Sections

S.No. Type of Road
Base Non Base
1 Four lane Divided Urban Road 11 26

2 Six Lane Divided Urban Road 11 6
3 Eight Lane Divided Urban Road 4 2
4 Ten lane Divided Urban Road 3 1
5 Two Lane Undivided Urban Road 2 1

Urban Roads

Chapter 6:
Signalized Intersections
TABLE OF CONTENTS
Section Page
Title
Number Number
Study Team i
List of Figures vii
List of Tables viii
List of Abbreviations ix
6.1 INTRODUCTION 1
6.3 BASE INTERSECTION 3
6.5 METHODOLOGY 4
6.5.1 Input Parameters 5
6.5.2 Geometric Characteristics 5
6.5.4 Control Characteristics 8
6.6 ESTIMATION OF SATURATION FLOW 9
6.6.1 Adjustment Factor for Bus Blockage 10
Adjustment Factor for Blockage by

6.6.2 10
Standing Right-turn Vehicles
6.6.3 Adjustment Factor for the Initial Surge of Vehicles 11
6.7 CAPACITY AND v/c RATIO 12
6.7.1 Capacity 12
6.7.2 Volume to Capacity Ratio 12

6.8 DELAY ESTIMATION 13
6.8.1 Control Delay Model 13
6.8.2 Intersection Delay 14
6.9 ESTIMATION OF LEVEL OF SERVICE 14
6.9.1 LOS Based on Control Delay 14
6.9.2 LOS Based on Volume Capacity Ratio (v/c) 15
6.10.1 Estimation of Capacity of an Intersection 16
Estimation of Capacity of intersection with

6.10.2 19
Exclusive Right Phase
REFERENCES 23
Annexure 6A: FIELD DATA COLLECTION STRATEGY 25
Annexure 6B: FIELD MEASUREMENT OF SATURATION FLOW 26
Annexure 6C: DETAILS OF PCU AND

28
SATURATION FLOW ESTIMATION MODEL
6C.1 Typical Discharge Pattern 28
6C.2 Optimization Model 28
6C.3 Saturation Flow Model for Base Intersection 29
Annexure 6D: FIELD MEASUREMENT OF STOPPED DELAY AND ITS

31
CONVERSION TO CONTROL DELAY
Annexure 6E: DETAILS OF CALIBRATION OF CONTROL DELAY MODEL 33
6E.1 Delays at Signalized Intersection 33
6E.2 Stopped Delay to Control Delay Conversion Factor 33
6E.3 Calibration of Control Delay Estimation Model 34

Annexure 6F: DETAILS OF USER PERCEIVED SIGNALIZED INTERSECTION LOS 37
6F.1 General Guidelines 37
6F.2 User Perception Survey 37
Annexure 6G: DETAILS OF ADJUSTMENT FACTORS 41
6G.1 Introduction 41
6G.2 Adjustment Factor for Bus Blockage 41
6G.3 Adjustment for Blockage by Standing Right-Turn Vehicles 41
6G.4 Adjustment Factor for Initial Surge of Vehicles 41
CSIR - Central Road Research Institute, New Delhi Page 6 - vi

6.1 INTRODUCTION
Intersections are the critical points of any road network, where delay normally occurs due
to sharing of space and time between conflicting streams / movements of vehicles. Depending upon
the type of control employed at the intersection, hierarchically can be termed as uncontrolled, stop
controlled, roundabout, signalized, grade separated intersection i.e. flyover and interchange. This
chapter deals with the methodology devised for determination of capacity and Level of Service (LOS)
of signalized intersections. It is imperative to study the varying typologies of signalized intersections
to arrive at the capacity and LOS norms under different operating conditions.
Accordingly, this chapter describes the methodology for the estimation of saturation flow,
capacity, delay and LOS for varying typologies of signalized intersections. The models developed
deal primarily with fixed time isolated signal controlled intersections. The methodology considers
a variety of prevailing operating conditions such as traffic composition, flow movements, geometric
characteristics and signal settings at such intersections.
Using this methodology, the saturation flow and delay can be estimated for existing signalized
intersections or for a newly planned intersection. Moreover, in the case of existing signalized
intersections, the users have the option of either using the models developed for the estimation of
saturation flow and control delay or directly obtain these parameters through field measurement
procedures prescribed in this manual. Further, adjustment factors accounting for the ground
conditions existing at any non-base intersections are also proposed in the manual which can be used
to obtain the prevailing saturation flows and capacity.

6.3 BASE INTERSECTION
In this manual, an intersection is categorized as base intersection if it conforms to the
following listed conditions:
• Each approach is uniform in its width leading to the stop line.
• There is no bus stop (far side or near side) in the vicinity i.e. within 75 m from the nearest stop
line of intersection.
• The pedestrian flow is negligible, or phasing plan allows protected pedestrians crossing at
the intersection.
• The longitudinal gradient of all the approaches is almost zero.
• Through vehicles are not hindered by the right turning vehicles sharing the same approach
and waiting for their phase.
If the candidate intersection considered by the analyst does not conform to the aforesaid
conditions, then such intersections are to be classified as non-base intersections and adjustment
factors need to be applied for the deviations from the base conditions.
6.4 SCOPE AND LIMITATION

This chapter presents concepts and procedures for the estimation of capacity and LOS offered
by the fixed time isolated signal controlled intersections. For the purpose of estimation of saturation
flow and capacity, 23 signalized intersections possessing varying typologies located in 8 cities of the
country namely; Delhi, Mumbai, Kolkata, Chennai, Ahmedabad, Vadodara, Surat and Noida have been
considered for analysis. In the case of delay and Level of Service (LOS) estimation, perception data
of the vehicle users on the quantum of delay encountered as well as basic socio-economic aspects of
the respondents has been collected at 18 signalized intersections located in Delhi, Mumbai, Kolkata
and Noida. The above perception data has been collected by interviewing the respondents both at the

approach arms of the intersections as well as by intercepting the respondents at the parking lots /
fuel stations located adjacent to the above 23 intersections selected for saturation flow and capacity
analysis.
6.5 METHODOLOGY ...

Chapter 7:
Roundabouts
Roundabouts
TABLE OF CONTENTS
Section Page
Title
Number Number
Study Team i
List of Figures vi
List of Tables vii
7.1 INTRODUCTION 1
7.1.1 Mini Roundabouts 1
7.1.2 Single Lane Roundabouts 2
7.1.3 Multilane Roundabouts 2
7.3.1 Geometric Parameters 4
7.3.2 Flow Parameters 5
7.3.3 Driver Behaviour Parameters 6
7.3.4 Performance Parameters 7
7.4 METHODOLOGY 7
7.5 INPUT PARAMETERS 7
7.5.1 Geometric Characteristics 9
7.5.3 Driver Behaviour 11
7.6 CAPACITY ESTIMATION 11

Roundabouts
7.7 LEVEL OF SERVICE 13
7.8.1 Estimation of Capacity of LOS of a 66 m Diameter Roundabout 14
7.8.2 Estimation of Capacity and LOS of a 45 m Diameter Roundabout 17
REFERENCES 20
ANNEXURE 7A: METHOD OF DATA COLLECTION AND DATA RETRIEVAL 21
7A.1 Measurement of Geometric Elements 21
7A.2 Retrieval of Gap Data from Video and Data Entry Sheet 21
7A.3 Gap Data Extraction 22
7A.4 Critical Gap and Follow-up Time 24
ANNEXURE 7B: METHOD FOR ESTIMATION OF PASSENGER CAR UNITS 25
ANNEXURE 7C: METHOD FOR ESTIMATION OF CRITICAL GAP AND FOLLOW-UP

27
TIME
7C.1 Calculation of Critical Gap 27
7C.2 Calculation of Follup-up Time 28

Roundabouts
7.1 INTRODUCTION
At grade intersections are the critical points of a road network where delay normally occurs
due to sharing of space and time between conflicting streams / movements of vehicles. Depending
upon the type of control employed, intersections can be termed as uncontrolled intersections,
stop-controlled intersections, roundabouts, signal controlled / signalized intersections and grade
separated intersections or interchanges. It is necessary to study them to arrive at various capacity and
Level of Service (LOS) norms under different operating conditions. This chapter presents concepts
and procedures for estimating the capacity and LOS of Roundabouts.
A roundabout is a specialized form of at-grade intersection where vehicles from the converging
arms are forced to move round a central island in one direction in an orderly and regimented manner
and move/weave out of the roundabout into their desired direction. In a conventional roundabout,
traffic at entry seek suitable gap in the circulating stream to negotiate at the roundabout.
Roundabouts are categorized according to size and environment to facilitate analysis of
specific performance or design issues. There are three basic categories based on environment,
number of lanes and size.
• Mini Roundabouts
• Single Lane Roundabouts
• Multilane Roundabouts
7.1.1 Mini Roundabouts

Mini roundabouts are small roundabouts with a fully traversable central island. Figure
7.1 shows the features of a typical mini roundabout. They may be useful in environments where
a conventional roundabout design is not possible due to constraints of Right of Way (RoW). Mini
roundabouts are relatively less expensive because they typically require minimal additional pavement
at the intersecting roads and minor widening at the corner of kerb. They are generally recommended
when there is insufficient RoW to accommodate the design vehicle with a traditional single-lane
roundabout. They are small in diameter (ranging from 4 m to 12 m). Mini roundabouts are perceived
Figure 7.1: Typical Mini Roundabout

Roundabouts
as pedestrian friendly due to short crossing distances coupled with low speed of vehicles on each
of the entry and exit approaches. A fully traversable central island is provided to accommodate
large vehicles and it serves as one of the distinguishing features of a mini roundabout. It is basically
designed to accommodate passenger cars without requiring them to traverse over the central island
accompanied by the basic philosophy of applicable for the roundabouts so as to provide ‘priority
to circulating traffic from the right’. Vehicles entering the roundabout must give way to vehicles
approaching from the right, circulating the central island. The capacity and LOS estimation of mini
roundabouts has not been dealt within this manual due to non-availability of such roundabouts to
study the traffic characteristics in Indian cities.
7.1.2 Single Lane Roundabouts

This type of roundabout is characterized as having a single-lane entry at all legs and one
circulatory lane. Figure 7.2 shows the features of a typical single lane roundabout having a diameter
ranging from 27 m to 55 m. They are distinguished from mini-roundabouts by their larger inscribed
circle diameter and non-traversable central-islands. Their design allows slightly higher speeds at
the entry, on the circulatory roadway and at the exit. The geometric design typically includes raised
splitter islands, a non-traversable central island, crosswalks and a truck apron/ mountable area.
The size of the roundabout is largely influenced by the choice of a design vehicle and available RoW.
However, again the capacity and LOS estimation of single lane roundabouts has not been dealt in this
manual due to inadequate representation of such roundabouts to study the traffic characteristics in
Indian cities.
Figure 7.2: Typical Single Lane Roundabout
7.1.3 Multilane Roundabouts

Multilane roundabouts have at least one entry with two or more lanes. In some cases, the
roundabout may have different number of lanes on one or more approaches (e.g., two lane entry on
the major approach and one lane entry on the minor approach). They also include roundabouts with
entries on one or more approaches that flare from one to two or more lanes. These require wider
circulatory roadways to accommodate more than one vehicle travelling side by side. Figure 7.3 shows
the features of a typical multi-lane roundabout having a diameter ranging from 46 m to 90 m. The

Roundabouts
speeds at the entry on the circulatory roadway and at the exit are similar or may be slightly higher
than those for the single lane roundabouts. The geometric design will include raised splitter islands,
truck apron, a non-traversable central-island and appropriate entry path deflection.
Figure 7.3: Typical Multilane Roundabout
7.2 BASE CONDITIONS FOR CAPACITY ESTIMATION

Based on the study of typology of over 350 roundabouts located in different parts of India, it is
found that more than 70 percent roundabouts possess 20 m to 70 m diameter and average diameter
of roundabouts in Indian cities / town is 35 m. This chapter presents concepts and procedures for the
estimation of capacity and LOS of multilane roundabouts of diameter of 20 m to 70 m with two lane
approach roads having mixed traffic flow conditions. The methodology proposed is applicable to base
roundabouts satisfying most of the requirements mentioned below:
• Roundabouts at Four-arm intersection having two-lane approaches only.
• Roundabouts have circular shape of Central Island.
• Roundabouts shall have three-lane weaving width.
• Intersection angle shall preferably be at 90 degree +/- 10 degree.
• Central Island diameter in the range of 20 m to 70 m.
• Roundabouts catering to low percentage of two wheelers and less than 5 per cent heavy
vehicles and Non-Motorised Traffic (NMT).
The methodology allows the analyst to assess the operational performance and capacity of
existing or planned roundabouts based on the given traffic demand levels.

Chapter 8:
Unsignalized Intersections
TABLE OF CONTENTS
Section Page
Title
Number Number
Study Team i
List of Figures v
List of Tables vi
8.1 INTRODUCTION 1
8.2 DEFINITIONS OF TERMINOLOGIES 2
8.3 BASE INTERSECTION 4
8.4 SCOPE LIMITATION 4
8.5 METHODOLOGY 5
8.5.1 Input Data: Step 1 6
8.5.2 Convert Traffic Volume into PCU:: Step 2 7
8.5.3 Calculate Conflicting Traffic Flow Rates: Step 3 9
8.5.4 Determine Critical Gap Value from Tables: Step 4 12
8.5.5 Calculate Capacity of a Movement: Step 5 13
8.5.6 Level of Service: Step 6 13
8.6.1 Estimation of Capacity of Three-Legged Intersection 14
8.6.2 Estimation of Capacity of Four-Legged Intersection 16
REFERENCES 20
ANNEXURE 8A : CALCULATION OF CRITICAL GAP USING OCCUPANCY TIME
22
METHOD
ANNEXURE 8B : PASSENGER CAR EQUIVALENT BASED ON OCCUPANCY TIME 24
ANNEXURE 8C: GAP MEASUREMENT AT REFERENCE LINE 25

8.1 INTRODUCTION
An unsignalized intersection refers to “an intersection without signal or manual control
and also without any central island”. It is formed when two roads intersect (or join) each other at
grade. Based on the relative importance of the two roads, one of them is generally designated as
major road and the other as minor road. When traffic on minor road is controlled by STOP signs, the
intersection is called a Two-Way Stop Controlled (TWSC). In case STOP signs are placed on all the
approaches of an intersection, it is termed as an All Way Stop Controlled (AWSC) intersection. Due to
weak enforcement of traffic regulations and lack of understanding of priority rules among road users
in India, no distinction is made in this manual between a TWSC and AWSC intersection.
An unsignalized intersection can be three legged, four legged or multi-legged type. A typical
three-legged intersection is formed when a side street joins a major street (refer Figure 8.1). A four-
legged intersection is formed when two roads cross each other. One of the two roads are generally
a minor street but both streets can also be minor / major street (refer Figure 8.2). A limited priority
of movement is followed by road users in India. Considering the above circumstances, the road that
is wider among the two or which carries heavy volume of traffic in an unsignalized intersection is
considered as ‘major’ road and the other intersecting road is considered as ‘minor’ road. The methods
presented in the manual are applicable for three legged and four legged unsignalized intersections
only.
Figure 8.1: Typical Three-Approach Intersection with Four Lane Divided

Carriageways on all Approaches

Figure 8.2: Typical Four-Approach Intersection with Two Lane Undivided

Carriageways on all Approaches
8.2 DEFINITIONS OF TERMINOLOGIES ...
8.3 BASE INTERSECTION
In this manual, an unsignalized intersection is categorized as base intersection if it conforms
to the conditions listed below:
• Number of intersecting approaches = 3 or 4
• Angle of intersection at 90 degrees on a three or four-legged intersection with a deviation of
+/- 10 degrees.
• 2 or 4 lane divided major road
• Negligible presence of non-motorized traffic, on-street parking, hawkers or any other landuse
activities within 75 m from the centre of the intersection
• No gradient on the intersecting approaches
• Safe stopping sight distance is available
• No speed breakers on any approach within 75 m from the centre of intersection
If the candidate intersection considered by the analyst does not conform to the previously
mentioned conditions, then such intersections are to be classified as non-base intersections and
adjustment factors need to be applied for deviations from the base conditions.
8.4 SCOPE AND LIMITATION

This chapter presents the concepts and procedures for the estimation of capacity and Level
of Service (LOS) offered by the three legged and four legged unsignalized intersections only. In
this context, 12 unsignalized intersections possessing varying three legged as well as four-legged
configuration has been considered. These intersections are located in eight metropolitan cities of the
country namely, Delhi, Navi Mumbai, Maraimalainagar (on the outskirts of Chennai), Thiruvanthapuram,
Bhubaneshwar, Meerut, Faridabad and Noida.

8.5 METHODOLOGY ...

Chapter 9:
Pedestrian Facilities
TABLE OF CONTENTS
Section Page
Title
Number Number
Study Team i
List of Figures vi
List of Tables vii
List of Abbreviations ix
9.1 INTRODUCTION 1
9.1.1 Overview 1
9.1.2 Modal Characteristics 1
9.1.3 Human Factors 1
9.1.4 Variations in Demand across Pedestrian Facilities 2
9.2.1 Definitions 5
9.2.2 Pedestrian Space Requirements 6
9.3 WALKIING SPEED AT FOOTPATHS 7
9.4 WALKING SPEED AT CROSSWALKS 7
9.4.1 Pedestrian Critical Gap at Crosswalks 8
9.4.2 Pedestrian Waiting Time at Crosswalks 8
9.5 PEDESTRIAN FLOW MODELS 9
9.5.1 Principles of Pedestrian Flow 9
9.5.2 Macroscopic Modelling 9
9.6 FUNDAMENTAL RELATIONSHIPS 10
9.6.1 Footpaths 10
9.6.2 Stairways 11
9.6.3 Foot Over Bridges 12
9.7 PEDESTRIAN LEVEL OF SERVICE (PLOS) 12
9.7.1 PLOS Ranges for Different Facilities 12
9.7.2 Methodology for Determination of PLOS 13
9.8 QUALITATITVE ASSESSMENT OF PEDESTRIAN FACILITY 15

9.9 EXAMPLE PROBLEMS 16

9.9.1 Example Problem 1 17
REFERENCES 21
ANNEXURE 9A : PEDESTRIAN CHARACTERISTICS AT FOOTPATHS 22
ANNEXURE 9.B : PEDESTRIAN CHARACTERISTICS AT CROSSWALKS 26
9B.1 Pedestrian Speed Characteristics at Crosswalks 26
9B.2 Pedestrian Critical Gap 26
9B.3 Waiting Time 27
ANNEXURE 9.C : PEDESTRIAN CHARACTERISTICS ON STAIRWAYS 28
ANNEXURE 9.D : PEDESTRIAN CHARACTERISTICS AT FOOT OVER BRIDGES 30
ANNEXURE 9.E : QUALITATIVE ASSESSMENT OF PEDESTRIAN FACILITY 31

9.1 INTRODUCTION
9.1.1 Overview
The definition of ‘Pedestrian’ includes people who walk, sit, stand in public spaces or use
mobility aids like walking stick, crutches or wheelchair, be they children, teenagers, adults, elderly
persons, persons with disabilities, workers, residents, shoppers or people watchers (IRC, 103:2012).
Walking is the basic mode of travel. It is healthy and sustainable to human society. As compared to
railways and vehicular transport, walking can happen anywhere: from roadside to covered shopping
malls and from underground stations to foot over bridges. Walking is still the most universal means
of travelling, especially for the first and the last trip leg of a journey. The importance of pedestrian
movements is understood globally and need not be overemphasized. Hence the pedestrian facilities
are analyzed by using factors like speed, pedestrian flow and density culminating with capacity and
Level of Service (LOS) of various forms of pedestrian facilities. Apart from these quantitative factors,
qualitative factors like pedestrian needs and perceptions of the pedestrians in the form of subjective
data are also included in defining Walkability Index for Footpaths are also dealt in this manual.
9.1.2 Modal Characteristics ...

Chapter 10:
Travel Time Reliability
as a Performance Measure
for Interurban and Urban Corridors
Travel Time Reliability as a Performance Measure for Interurban and Urban Corridors
TABLE OF CONTENTS
Section Page
Title
Number Number
Study Team i
Contribution of Students ii
List of Figures iv
List of Tables v
List of Abbreviations vi
10.1 INTRODUCTION 1
10.2 URBAN AND INTER URBAN CORRIDORS 1
10.2.1 Uninterrupted Flow in Urban Corridor 1
10.2.2 Interrupted Flow in Urban Corridor 1
10.2.3 Interurban Corridor 2
10.3 DEFINITIONS OF TERMINOLOGIES 2
10.4 FACTORS INFLUENCING TRAVEL TIME RELIABILITY 4
10.6 METHODOLOGY 5
10.7 PROCEDURE FOR TRAVEL TIME RELIABILITY AND LOS 5
10.8 TRAVEL TIME 6
10.9 TRAVEL TIME RELIABILITY ANALYSIS 8
10.10 LOS BASED ON TRAVEL TIME FOR PRIVATE VEHICLES 9
10.11 LOS BASED TRAVEL TIME RELIABILITY FOR PRIVATE VEHICLES 10
10.11.1 LOS Based on PT and BT 10
10.11.2 LOS Based on PTI and BTI 10
10.12 LOS FOR BUS RAPID TRANSIT SYSTEM (BRTS) 11
10.13 RELIABILITY BASED LOS FOR BRTS 12
10.14 RELIABILITY ANALYSIS FOR NORMAL PUBLIC TRANSIT SYSTEMS 13
RELIABILITY BASED LOS FOR INTERRUPTED 6-LANE DIVIDED
10.15 14
ARTERIAL CORRIDOR USING TWO WHEELER TRAVEL TIME
RELIABILITY BASED LOS FOR INTERRUPTED 4-LANE DIVIDED
10.16 14
ARTERIAL CORRIDOR USING CAR TRAVEL TIME
10.17.1 Understanding of PTI and BTI 15
10.17.2 LOS based on PT and PTI for car on urban interrupted section 15
REFERENCES 17

10.1 INTRODUCTION
The concept of reliability helps in understanding two operating states, implying thereby
whether the road is connected or disconnected. This binary state approach limits the application to
everyday situation where road links are operating in between these two extremities. Also, the aspects
of this reliability are less useful to the road users than the transport system planners. This limitation,
further led to the development of various network reliability measures such as travel time reliability,
capacity reliability, parking reliability etc. Out of the various network reliability measures, travel time
reliability is considered as a useful tool for the road users as well as for the public transit system
planners. Since 1990, network reliability has been prominent research topic in transport planning
in Japan, especially after the Kobe earthquake of 1990. In its immediate aftermath, measures have
been undertaken on Japanese road network aimed at providing enhanced connectivity and reliability.
Travel Time Reliability concept was introduced by Asakura (Asakura and Kashiwadani 1991) by
considering selected network of roads in Japan. It was defined as the probability that the trip between
a given Origin - Destination (O-D) pair can be made with a certain degree of reliability under varying
time periods of the day and specified Level of Service. This measurement is found to be useful while
evaluating network performance under normal daily flow variations and various uncertainties.
In this regard, travel time reliability is an important attribute of urban transportation
services affecting choice of mode and route of travel. It is a measure of a roadway service quality
in transport network. Reliability by its nature implies about the certainty or stability of travel time
whereby it eliminates uncertainty for travelers in the sense that the travelling public does not have
to travel with any degree of uncertainty in respect of the probable / reliable time of arrival at their
respective destinations. This analogy is applicable to a large extent on the urban and interurban
carriageways and their characteristics are discussed in the succeeding sections.
10.2 URBAN AND INTERURBAN CORRIDORS

10.2.1 Uninterrupted Flow in Urban Corridor
Uninterrupted urban arterial section is a typical ideal / base section. Vehicular speeds along
this section does not get influenced due to merging or diverging traffic joining from the left-in and
left-out access roads. Moreover, the candidate road section should not have influence due to any form
of roadside friction (like on-street parking, kerb side bus stops) and presence of any sharp horizontal
curves and steep vertical gradients. The length of the selected uninterrupted section ranges from
2.5 to 3 km. Figure 10.1 presents the typical uninterrupted flow section of an urban arterial corridor
considered in this manual.
Figure 10.1: Typical Section of Urban Corridor of Uninterrupted flow section
10.2.2 Interrupted Flow in Urban Corridor

Interrupted Urban Corridor is a typical section of urban arterials witnessed in many of the
metropolitan cities of India. This section is largely influenced by major controlled intersections
(ranging between one to two intersections) and hence the speed of the vehicles along this section

would get influenced due to merging or diverging traffic joining from the adjoining network.
Moreover, the candidate road section should not have influence due to any form of roadside friction
(like the influence of on street parking, kerb side bus stops) and should not have any influence due to the
presence of any sharp horizontal curves and steep vertical gradients. The length of the interrupted
section is expected to be 1.5 km to 3 km. The location of controlled intersection is at least 500 m away
from the start and the end points of the study section. Figure 10.2 presents the typical interrupted
flow section of an urban arterial corridor considered in this manual.
Figure 10.2: Typical Section of Urban Corridor of Interrupted flow section
10.2.3 Interurban Corridor

Such a test section invariably exists beyond the urban periphery on the National Highways
or State Highways connecting major cities. Such road sections should not have influence due to the
aforesaid urban conditions except for catering to insignificant proportion of Left-in and Left-out
traffic from minor road (Figure 10.3). The length of the test section considered for analysis is at least
3 km which is termed as interurban corridor in this manual.
Figure 10.3: Typical section of Interurban Corridor of Interrupted Flow section

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Indian

Highway Capacity Manual (Indo-HCM)

About the Manual

CSIR âè °â ¥æ§ü ¥æÚU - ·ð´¤¼ýèØ âÇ¸U·¤ ¥Ùéâ¢ÏæÙ â¢SÍæÙ, Ù§ü çÎËÜè-vv®®wz

About the Manual

CSIR âè °â ¥æ§ü ¥æÚU - ·ð´¤¼ýèØ âÇ¸U·¤ ¥Ùéâ¢ÏæÙ â¢SÍæÙ, Ù§ü çÎËÜè-vv®®wz

Indian Institute of Technology (IIT) Roorkee, Roorkee

Indian Institute of Technology (IIT) Bombay, Mumbai

Indian Institute of Technology (IIT) Guwahati, Guwahati

School of Planning and Architecture (SPA), New Delhi

Sardar Vallabhai Patel National Institute of Technology (SVNIT), Surat

Indian Institute of Engineering and Sciences University (IIEST), Shibpur

Anna University (AU), Chennai

Automatic Road Survey System (ARSS) Team: CSIR - CRRI

CSIR - Central Road Research Institute, New Delhi Page i

1 CHAPTER 1: Basic Concepts and

2 CHAPTER 2: Single Lane, Intermediate

3 CHAPTER 3: Multilane Divided Interurban

4 CHAPTER 4: Interurban and Urban

5 CHAPTER 5: Urban Roads 5 - 1 to 5 - 34

6 CHAPTER 6: Signalized Intersections 6 - 1 to 6 - 43

8 CHAPTER 8: Unsignalized Intersections 8 - 1 to 8 - 25

9 CHAPTER 9: Pedestrian Facilities 9 - 1 to 9 - 36

10 CHAPTER 10: Travel Time Reliability as a

CSIR - Central Road Research Institute, New Delhi Page iii

18.12.2017 (Satish Chandra)

CSIR - Central Road Research Institute, New Delhi Page v

CSIR - Central Road Research Institute, New Delhi Page vii

CSIR - Central Road Research Institute, New Delhi Page viii

STRUCTURE OF INDO - HCM

CSIR - Central Road Research Institute, New Delhi Page ix

NEW CONCEPTS IN INDO-HCM

Capacity and Level of Service of Mid Block Sections

CSIR - Central Road Research Institute, New Delhi Page x

Saturation Flow and Capacity of Signalized Intersections

Critical Gap and Capacity of Roundabouts

CSIR - Central Road Research Institute, New Delhi Page xi

Critical Gap and Capacity of Unsignalized Intersections

Capacity of Pedestrian Facilities

CSIR - Central Road Research Institute, New Delhi Page xii

Travel Time Reliability as a Performance Measure for Interurban and

Innovative Process of Manual Development

CSIR - Central Road Research Institute, New Delhi Page xiii

CSIR - Central Road Research Institute, New Delhi Page xiv

CSIR - Central Road Research Institute, New Delhi Page xv

CSIR - Central Road Research Institute, New Delhi Page 1 - iii

1.2 STUDY OBJECTIVES AND SCOPE

CSIR - Central Road Research Institute, New Delhi Page 1 - 1

1.3 MODUS OPERANDI

1.4 PURPOSE OF INDO-HCM

1.5 DEFINITION OF TERMINOLOGIES ...

CSIR - Central Road Research Institute, New Delhi Page 1 - 2

List of Abbreviations vii

2.2 DEFINITIONS AND TERMINOLOGIES 1

2.3 FUNCTIONAL CHARACTERISTICS 3

2.3.1 Two Lane Roads 3

2.3.2 Intermediate Lane Roads 4

2.3.3 Single Lane Roads 4

2.4 BASE CONDITIONS FOR CAPACITY ESTIMATION 4

2.5 SCOPE AND LIMITATION 5