Malla Reddy Institute of Technology & Science: Department of Civil Engineering

MALLA REDDY INSTITUTE OF TECHNOLOGY & SCIENCE
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DEPARTMENT OF CIVIL ENGINEERING
MRITS Civil Engineering Department
TRANSPORTATION ENGINEERING
CE504PC
UNIT-I
INTRODUCTION
By Mr.M.Gnanendra Babu
Assistant Professor,
Department of Civil Engineering,
Malla Reddy Institute of Technology & Science.(MRITS)
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Pre-Requisites: Surveying, Engineering Drawing, AutoCAD
Software.
Course Objectives:This course aims at providing a comprehensive
insight of various elements of Highway transportation engineering.
Topics related to the highway development, characterization of
different materials needed for highway construction, structural and
geometric design of highway pavements along with the challenges
and possible solutions to the traffic related issues will be covered as a
part of this course.
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Course Outcome: At the end of this course, the students will develop:
An ability to apply the knowledge of mathematics, science and engineering in
the areas of traffic engineering, highway development and maintenance
An ability to design, conduct experiments to assess the suitability of the highway
materials like soil, bitumen, aggregates and a variety of bituminous mixtures. Also
the students will develop the ability to interpret the results and assess the suitability
of these materials for construction of highways.
An ability to design flexible and rigid highway pavements for varying traffic
compositions as well as soil subgrade and environmental conditions using the
standards stipulated by Indian Roads
Congress.
An ability to evaluate the structural and functional conditions of in-service
highway pavements and provide solution in the form of routine maintenance
measures or designed overlays using Indian Roads congress guidelines.
An ability to assess the issues related to road traffic and provide engineering
solutions supported with an understanding of road user psychological and
behavioural patterns.
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Text Books:
1. Khanna, S.K, Justo, A and Veeraragavan, A, ‘Highway
Engineering’, Nem Chand & Bros. Revised Tenth Edition, 2014
2. Kadiyali L.R. and Lal N B, Principles and Practices of Highway

Engineering; Seventh Edition, First Reprint; Khanna Publishers, New
Delhi, 2018
Code of Provisions:
Design Codes: IRC 37-2012, IRC 58-2015, IRC 81-1997
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References:
1. Papacoastas, C. S. and Prevedouros, Transportation Engineering and
Planning, Third Edition, Third Impression; Pearson Education, 2018.
2. Khisty C J and Lall B Kent; Transportation Engineering: An Introduction,
Third Edition, 1st Indian Adaptation; Pearson India Education Service Pvt. Ltd,
New Delhi 2017.
3. Subhash C Saxena, Text Book of Highway and Traffic Engineering; First
Edition; CBS Publishers and Distributors. New Delhi, 2014
4. C Venkatramaih, Transportation Engineering Volume 1 – Highway
Engineering, 1st Edition, Universities Press, 2016
5. Garber, N.J. and Hoel, L.A. Traffic and Highway Engineering, Fourth
Edition; Cengage
Learning, Stamford, CT, USA, 2010
6. Partha chakroborty and Animesh Das, Principles of Transportation
Engineering, PHI, 2013
7. Nicholas J Garber and Lester A Hoel, Traffic and Highway Engineering, 5th
Edition, Cengage Learning India Private Limited, New Delhi, 5th Indian
Reprint, 201
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UNIT – I Contents
Introduction,
History and Importance of Highways,
Characteristics of road transport,
Current road development plans in India,
Highway development in India,
Highway planning,
Highway alignment,
Engineering surveys for Highway alignment,
Highway projects,
Highway drawings and reports,
Detailed Project Report preparation,
PPP schemes of Highway Development in India,
Government of India initiatives in developing the highways and
expressways in improving the mobility and village road development in
improving the accessibility.
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Transportation engineering
• Transportation engineering is the application
of technology and scientific principles to the
planning, functional design, operation and
management of facilities for any mode of
transportation in order to provide for the safe,
efficient, rapid, comfortable, convenient,
economical, and environmentally compatible
movement of people and goods from one place
to other.
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MODES OF TRANSPORTATION
• Basic mode of transportation are

 Land
• Roadway
• railway
 Water
 Air
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MODES OF TRANSPORTATION
• Highways
Car, Bus, Truck, non- motorized ..etc
• Railways
Passenger and Goods
• Airways
Aircraft and Helicopters
• Waterways
Ships, boats…
• Continuous Flow systems
Pipelines,belts,elevetor,ropeway…etc.
• Merits and Demerits: Based on accessibility, mobility, cost, tonnage..
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Airways
• Fastest among all other modes
• More comfortable
• Time saving
• Uneconomical
Waterways
• slowest among all other modes
• It needs minimum energy to haul unit load through unit
distance.
• This can be possible between ports on the sea routes or along
the river
• Economical
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Railways
• The transportation along the railways track could
be advantageous by railways between the stations
both for the passengers and goods, particularly
for long distance.
• It depends upon the road transport i.e. road could
serve as a feeder system.
• Energy require to haul a unit load through unit
distance by the railway is only ¼ to 1/5 of that
required by road.
• Safety
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Highways
• It gives the maximum service to one and all
• It gives maximum flexibility for travel with reference to route,
direction, time and speed of travel
• It provide door to door service
• Other modes are depend on it
• It requires small investment for the government
• Motor vehicles are cheaper than other carriers like rail locomotive
and wagons
• It saves the time for short distance
• High degree of accident due to flexibility of
movement
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Scope of highway engineering
• Development, planning and location
• Highway design, geometric and structure
• Traffic performance and its control
• Materials, construction and maintenance
• Economic, finance and administration
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ROLE /IMPACT OF TRANSPORTATION
• Economic Development
• Social Development
• Spatial Development
• Cultural Development
• Political Development
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HISTORICAL DEVELOPMENT OF ROAD
CONSTRUCTION
• Oldest mode
 Foot paths- animal ways, cart path……..
• As civilization evolved the need for transportation
increased
ROMAN ROAD-(500 B.C.)
 They were built straight regardless of gradient
 They were built after the soft soil was removed and
a hard stratum was reached.
 Thickness varies from 0.75 m to 1.2m
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Roman Road Construction
Basic cross section
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Modern Highway
Roman Roads
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Other oldest road transport are
• Tresaguet construction
• Metcalf construction
• Telford construction
• Mecadam construction
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Indian Roads
• India has a large road network of over 3.314
million kilometers of roadways (2.1 million
miles), making it 3rd largest road network in the
world.
• At 0.66 km of highway per square kilometer of

land the density of India’s highway network is
higher than that of the United States (0.65) and
far higher than that of China's (0.16) or Brazil's
(0.20).
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Highway Development In India
Roads in Ancient India
• The excavation of Mohenjo-Daro and Harappa have
reveled the existence of roads in India as early as 25
to 35 centuries B.C. Old Record reveal that in early
period the roads were considered indispensable for
administrative and military purposes. The ancient
scriptures refer to the existence of roads during the
Aryan Period in the fourth century B.C. Kautilya
the first prime minister of Emperor Chandra Gupt
Maurya, laid down the rules in the literary piece titled
‘ Arthrassastra’. Rules have been mentioned above
regulating the depth of roads for various purposes
and for different kinds of traffic.
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Roads in Ancient India
(Mohenjo-Daro and Harappa )
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Roads in Mugal Period
• During the Mugal Period, the roads of India
were greatly improved. Some of the
highways either built or maintained by mugals
received greater appreciation from the foreign
visitors who visited India during that periods.
Roads were built running from North-West
to the Eastern areas through the Gangetic
plains, linking also the coastal and central
parts.
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Roads in Mugal Period
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Roads in Nineteenth Century
• At the beginning of British rule, the condition of roads
deteriorated. The economic and political shifts caused
damage to a great extent in the maintenance of the road
transportation. The fall of Mugal empire led therefore to
the scant attention to the communication. Prior to the
Introduction of railways, a number of trunk roads were
metalled and bridges were provided. This was mainly
done on the remains of old roads which existed, under
the supervision of the British Military Engineers. In fact
there roads connected important military and business
centers. In 1865 Lord Dalhousie, when he was Governor-
General formed the Public works Department in more
or less the same forms that existed today.
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Roads in Nineteenth Century
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Highway Development in India
• Jayakar Committee (1927)
• Central Road Fund (1929)
• Indian Roads Congress (IRC), 1934
• Central Road Research Institute (CRRI), 1950
• Motor vehicle act (1936)
• National Highway Authority of India (NHAI),1995
• First twenty year road plan ( 1943-61 )
• Second twenty year road plan ( 1961-81 )
• Highway Research board ( 1973 )
• National Transport Policy committee ( 1978 )
• Third twenty year road plan ( 1981-2001 )
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Jaykar Committee and the recommendations
• After the first World War, motor vehicles using the
roads increased and this demand a better road
network which can carry both bullock cart traffic
and motor vehicles. The existing roads when not
capable to withstand the mixed traffic conditions. A
resolution was passed by both Chambers of the
Indian Legislature 1927 for the appointment of
committee to examine and report on the question of
Road development in India. In response to this
resolution, Indian Road Development Committee
was appointed in India by the government with
M.R. Jayakar as Chairman, in 1927.
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Jaykar Committee and
the Recommendations
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Jayakar Committee,1927
• After the first World War, motor vehicle using the roads
increases, this demanded a better road network.
• In 1927,Indian road development committee was appointed by the
government with M.R. Jaykar as chairman.
• Road development in the country should be made as a national
interest since local govt. do not have financial and technical capacity
for road development.
• An extra tax should be levied on petrol from road users to
create the road development fund.
• To establish a semi-official ,technical institution to pool technical
knowledge, sharing of ideas and to act as an advisory body.
• To create a national level institution to carry research ,
development works and consultation.
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Central road fund
• It was formed on 1st march 1929
• The consumers of petrol were charged an extra leavy
of 2.64 paisa per litre of petrol to built up this road
development fund.
• From this 20% of annual reveneu is to be retain as a
central reveneu for research and experimental work
expenses..etc
• Balance 80% is allowed by central govt. to
various states based on actual petrol
consumption or revenue collected.
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The Most Important recommendation made by the
committee are:
• The Road Development in the country should be
considered as a national Interest as this has become
beyond the capacity of provincial governments and
local bodies.
• An Extra tax should be levied on petrol from the
road user to develop a road development fund called
Central Road Fund.
• A semi-official technical committee should be
formed to pool technical know how from various
parts of the country and to act as an advisory body
on various aspects of roads.
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Central Road Fund , 1929
CRF Act , 2000
Distribution of 100% cess on petrol as follows:

 57.5% for NH
MORTH
 30% for SH
 12.5% for safety works on rail-Road crossing.
50% cess on diesel for Rural Road development
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Indian Roads Congress, 1934
• Central semi official body known as IRC was formed in 1934.
• To provide national forum for regular pooling of experience
and ideas on matters related to construction and maintenance of
highways.
• It is a active body controlling the specification,
standardization and recommendations on materials, design
of roads and bridges.
• It publishes journals, research publications and standard
specifications guide lines.
• To provide a platform for expression of professional
opinion on matters relating to roads and road transport.
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Indian Roads Congress
• At the instance of Central Government a semi-
official technical body known as Indian Road
Congress(IRC) was formed in 1934. The Indian
Roads Congress was constituted to provide a
forum for regular pooling of experience and ideas
on all matters affecting the planning, construction
and maintanence of roads in India, to recommend
standard specifications and to provide a platform
for the expression of professional opinion on
matter related to road engineering.
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• The IRC has played important role in the
formulation of the three 20-year road
development plans in India.
• Now the Indian Roads Congress has become an
active body of national importance controlling
specifications, standardizations, and
recommendations on material, design and
construction of roads and bridges.
• The IRC works in close collaboration with Roads
Wing of the ministry of Surface Transport,
Government of India.
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Motor vehicle act
• It was formed in 1939

• To regulate the road traffic in the form of
traffic laws, ordinances and regulations.
• Three phases primarily covered are control of
driver, vehicle ownership and vehicle
operation
• It was revised on 1988
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Motor Vehicle Act
• In 1939 the motor Vehicles Act was brought
into effect by the government of India to
Regulate the road traffic in the form of
traffic laws, ordinance and regulations. The
three phases primarily covered are control of
the driver, vehicle ownership and vehicle
operation on roads and in traffic stream. The
Motor vehicles Act has been revised in the
year 1988.
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Motor Vehicle Act
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Central road research institute(1950)
 Engaged in carrying out research and development
projects.
 Design, construction and maintenance of roads and runways,
traffic and transportation planning of mega and medium cities,
management of roads in different terrains,
 Improvement of marginal materials.
 Utilization of industrial waste in road construction.
 Landslide control.
 Ground improvements, environmental pollution.
 Road traffic safety.
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Central Road Research Institute
• In the year 1950 the central Road Research Institute
(CRRI) was started at New Delhi for research in
various aspect of highway engineering. It may be
indicated that one of the recommendation of jaykar
committee report was to setup a central organization
for research and dissemination of Information.
• The CRRI is one of the national laboratories of the
Council of Scientific and Industrial Research; the
institute is mainly engaged in applied research and
offer technical advice to state government and the
on various problems concerning roads.
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Central Road Research Institute
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National Highway Act
• In 1956 the National Highway act was passed
• The main features of the act are:
• The responsibility of developing and
maintenance of the national highway (NH) to
be provisionally taken by the central
government.
• The Central Government to be empowered to
declare any other highway as NH or to omit
any of the existing highway from the list.
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National Highway Act
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Ministry of Road Transport & Highways
• Planning, development and maintenance of

National Highways in the country.
• Extends technical and financial support to State
Governments for the development of state roads and
the roads of inter-state connectivity and economic
importance.
• Evolves standard specifications for roads and
bridges in the country.
• It stores the data related to technical knowledge on
roads and bridges.
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Highway Research Board
• To ascertain the nature and extent of

research required
• To correlate research information from various
organisation in India and abroad.
• To collect and correlation services.
• To collect result on research
• To channelise consultative services
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Highway Research Board
• The Highway Research Board of the Indian Road
Congress was set up in 1973 with a view to give
proper direction and guidance to road research
activities in India.
• The Highway Research Board (HRB) has
recommended suitable financial allocation of
research by the central and state government and
has chosen high priority research schemes taken
up first.
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• The objectives of IRC Highway Research Board
are:
• To ascertain the nature and extent of research
required.
• To correlate research Information from
various organizations in India and aboard with
a view to exchange publications and information
on roads.
• To Co-ordinate and conduct correlation
services.
• To Collect and disseminate results on research
• To Channelize consultative services.
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Classification of Highways
Depending on weather
 All weather roads
 Fair weather roads
Depending the type of Carriage way

 Paved roads(WBM)
 Unpaved roads(earth road or gravel road)
Depending upon the pavement surface

 Surfaced roads(bituminous or cement concrete
road)
 Un surfaced roads
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Classification of Highways
Based on the Traffic Volume
 Heavy
 Medium
 Light
Based on Load or Tonnage

Class 1 or Class 2 etc or Class A , B etc Tonnes per
day
Based on location and function ( Nagpur road plan )

 National highway (NH)
 State highway (SH)
 Major district road (MDR)
 Other district road (ODR)
 Village road (VR)
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Characteristics of Road Transport
• It is an accepted fact that of all the modes of
transport the transportation, road transport is the
nearest to the people. The passenger and the goods
have to be first transported by road before
reaching a railway station or a port or an airport.
The road network alone could serve the remotest
villages of the vast country like ours.
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• The characteristics of road transport are briefly listed here
• Roads are used by various types of road vehicles, like
passenger cars, buses, trucks. But railway tracks are used
only by rail locomotives and wagons.
• Road Transport requires a relative small investment for the
government. Motor vehicles are much cheaper than other
carriers like rail locomotives and wagons.
• Road transport offer a complete freedom to road user to
transfer the vehicles from one lane to another and from one
road to another according to the needs and convenience.
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• In particular for short distance travel, road transport

saves time. Trains stop at junctions and main stations for
longer time.
• Speed of movement is directly related with the severity
of accidents. The road transport is subjected to a high
degree of accidents due to the flexibility of movements
offered to the road users. Derailment of railway
locomotives and air crashes of air plane are also not
uncommon.
• Road Transport is the only means of transport that
offers itself to the whole community alike.
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Characteristics of road transport
• Roads are used by various types of road vehicles, like
passenger cars, buses, trucks, pedal cycle and animal
drawn vehicle.
• It requires a relatively small investment for the
government.
• It offers a complete freedom to road users to transfer
the vehicle from one lane to another and from one
road to another according to need and convenience.
• Speed and movement is directly related with the
severity of accident.
• Road transport is the only means of transport that offers
itself to the whole community alike.
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Based on modified system of
Highways classification
• Primary
 Expressways
 National Highways
• Secondary
 SH
 MDR
• Tertiary
 ODR
 VR
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Expressways
•Heavy traffic at high speed (120km/hr)
•Land Width (90m)
•Full access control
•Connects major points of traffic generation
•No slow moving traffic allowed
•No loading, unloading, parking.
The Mumbai-Pune Expressway as seen

from Khandala
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National Highways
• NH are the main highways running through the length and breadth of
India, connecting major parts,foreign highways,capital of large states
and large industrial and tourist centres including roads required for
strategic movements for the defence of India.
• The national highways have a total length of 70,548 kms. Indian
highways cover 2% of the total road network of India and carry 40%
of the total traffic.
• The highway connecting Delhi-Ambala-Amritsar is denoted as NH-1,
whereas a bifurcation of this highway beyond Jalandar to Srinagar and
Uri is denoted NH-1-A
• The longest highway in India is NH7 which stretches from Varansi in
Uttar Pradesh to Kanyakumari in the southern most point of Indian
mainland.
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National Highways cont…
• The shortest highway is NH47A which stretches from
Ernakulam to Kochi and covers total length of 4 Kms.
• Golden Quadrilateral – (5,846
Kms) Connecting Delhi -
Kolkata-Chennai-Mumbai
 NH-2 Delhi- Kol (1453 km)
 NH 4,7&46 Che-Mum (1290km)
 NH5&6 Kol- Che (1684 m)
 NH 8 Del- Mum (1419 km)
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State Highways
• They are the arterial roads of a state, connecting up with the
national highways of adjacent states, district head quarters and
important cities within the state.
• Total length of all SH in the country is 1,37,119 Kms.

• Speed 80 kmph
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Major District Roads
• Important roads with in a district serving

areas of production and markets ,
connecting those with each other or with
the major highways.
• India has a total of 4,70,000 kms of MDR.

• Speed 60-80kmph
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Other district roads
 serving rural areas of production and providing
them with outlet to market centers or other
important roads like MDR or SH.
 Speed 50-60kmph
Village roads
• They are roads connecting villages or group of
villages with each other or to the nearest road of a
higher category like ODR or MDR.
• India has 26,50,000 kms of ODR+VR out of the
total 33,15,231 kms of all type of roads.
• Speed-40-50kmph
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Urban Road Classification
• Arterial Roads
• Sub Arterial
• Collector
• Local Street
• Cul-de-sac
• Pathway
• Driveway
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ARTERIAL
• No frontage access, no standing vehicle,

very little cross traffic.
• Design Speed : 80km/hr
• Land width : 50 – 60m
• Divided roads with full or partial parking
• Pedestrian allowed to walk only at
intersection
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SUB ARTERIAL ROAD
• Bus stops but no standing vehicle.

• Less mobility than arterial.
• Spacing for CBD : 0.5km
• Design speed : 60 km/hr
• Land width : 30 – 40 m
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Collector Street
• Collects and distributes traffic from local
streets
• Provides access to arterial roads
• Located in residential, business and
industrial areas.
• Full access allowed.
• Parking permitted.
• Design speed : 50km/hr
• Land Width : 20-30m
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Local Street
• Design Speed : 30km/hr.

• Land Width : 10 – 20m.
• Primary access to residence, business or
other abutting property
• Less volume of traffic at slow speed
• Unrestricted parking, pedestrian movements.
(with frontage access, parked vehicle, bus
stops and no waiting restrictions)
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CUL–DE- SAC
• Dead End Street with only one entry access for entry
and exit.
• Recommended in Residential areas
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Driveway
• A driveway is a type of private road for local access

to one or a small group of structures, and is owned
and maintained by an individual or group.
• Driveways are commonly used as paths to
private garages, fuel stations, or houses
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First 20-years road plan(1943-63)
• The conference of chief engineer held at Nagpur in 1943
finalized the first 20-years road development plan for
India called Nagpur road plan
• Road network was classified into five categories.
• The responsibility of construction maintenance of NH was
assign to central govt.
• The target road length was 5,32,700 km at the end of
1961.
• Density of about 16km of road length per 100 sq. km area
would be available in the country by the year 1963.
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First 20-years road plan cont…
• The formulae were based on star and grid
pattern of road network.
• An allowance of 15% is provided for agricultural
industrial development during the next 20-years
• The length of railway track in the area was also
consider in deciding the length of first category
road. The length or railway track is directly
subtracted from the estimated road length of
metalled roads.
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Second 20-years road plan(1961-81)
• It was initiated by the IRC and was finalised in 1959 at
the meeting of chief engineers.
• It is known as the Bombay road plan.
• The target road length was almost double that of Nagpur
road plan i.e. 10,57,330 km.
• Density about 32 km per 100 sq. km. and an outlay of
5200 crores
• Every town with population above 2000 in plans and
above 1000 in semi hill area and above 500 in hilly
area should be connected by metalled road
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Second 20-years road plan cont…
• the maximum distance from any place in a semi develop
area would be 12.8 km from metalled road and 4.8 from
any road
• Expressways have also been considered in this plan and
1600km of length has been included in the proposed
target NH
• Length of railway track is considered independent of
road system
• 5% are to be provided for future development and
unforeseen factor
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Third twenty years road plan (1981-2001)
• The future road development should be based on the
revised classification of roads system i.e. primary,
secondary and tertiary
• Develop the rural economy and small towns with all
essential features.
• Population over 500 should be connected by all weather
roads.
• Density increases to 82 km per 100 sq. km
• The NH network should be expanded to form a square
grids of 100 km sides so that no part of the country is
more than 50 km away from the NH
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Third twenty years road plan cont…
• Expressway should be constructed along major traffic corridors
• All towns and villages with population over 1500 should be
connected by MDR and villages with population 1000-1500 by
ODR.
• Road should be built in less industrialized areas to attract the
growth of industries
• The existing roads should be improved by rectifying the defects in
the road geometry, widening, riding quality and strengthening the
existing pavement to save vehicle operation cost and thus to
conserve energy
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Road Patterns
• Rectangular or Block patterns

• Radial or Star block pattern
• Radial or Star Circular pattern
• Radial or Star grid pattern
• Hexagonal Pattern
• Minimum travel Pattern
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Current Highway Development In
India
• Some of the points which were given due
consideration while formulating the plan are
improvement of transportation facilities in
villages, towns, and small cities, conservation of
energy, preservation of environmental quality and
improvement in road safety.
• The twenty year road development plan aims at
increasing the total road length from 46 km per
100 sq km in the year 1981 to 82 km per 100 sq
km by the year 2001.
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Road Development Plan, Vision 2021
• The Indian Roads Congress have Prepared a Vision-2021
Document for road development in India
• The salient features of the plan are
• The road network shall be expanded as Under
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• Half of the national Highway length should have four/ six
lanes, and the remaining half should have two-lane
carriageways with hard shoulders..
• 10,000 Km of State Highways should have four lanes and
the balance should have two lanes
• Forty percent of the major District Roads should have
two lane carriageways
• The targets for basic access to village should have two
lane carriageways
• Maintenance of existing assets should receive adequate
attention
• Research and Development activities in the road Sector
should receive good attention
2/10/2021 97
• Alternative sources of funding such as toll financing,
creation of a dedicated Road Fund through additional levies
on fuel.
• Up-gradation of construction technology through
adoption of innovative procedures and specification should
be favored.
• Road safety should be enhanced through engineering
measures
• Environmental Concerns caused by road and road traffic
should be addressed
• Training of engineers should receive attention
• Greater recourse to Public- Private Partnership should be
taken
2/10/2021 98
Rural Roads , Vision 2025
• The Indian Roads Congress Have Prepared a
Rural Road Development Plan, Vision 2025 The
salient features of the Plan
• Master Plans should be Prepared for Rural
Roads showing the core Network which gives
accessibility to each village. All future
programmes should strictly conform to this
network
• All habitations with a population of above 100
will be connected by all weather roads
2/10/2021 99
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Rural Roads , Vision 2025
• It is estimated that a length of 2,90,000 Km of new
roads will be needed to achieve full connectivity. Out
of this 40,000 Km will be black topped and the
remaining 2,50,000 Km will be gravel.
• Up-gradation of existing Rural Roads shall be taken
up at a cost of Rs 1,64,000 crores.
• The maintenance of the rural road network will
require Rs 7,500 crores every year.
• Greater emphasis shall be given to adoption of new
technologies for construction and maintenance of
roads.
2/10/2021 101
Highway alignment and
surveys
2/10/2021 102
Highway alignment
• The position or lay out of centre line of the highway
on the ground is called the alignment.
• It includes straight path, horizontal deviation and
curves.
• Due to improper alignment , the disadvantages are,
 Increase in construction
 Increase in maintenance cost
 Increase in vehicle operation cost
 Increase in accident cost
• Once the road is aligned and constructed, it is not easy
to change the alignment due to increase in cost of
adjoining land and construction of costly structure.
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Requrements of highway alignment
 Short
 Easy
 Safe
 Economical
• Short- desirable to have a short alignment between two

terminal stations.
• Easy- easy to construct and maintain the road with minimum problem also easy
for operation of vehicle.
• Safe- safe enough for construction and maintenance from the view point of
stability of natural hill slope, embankment and cut slope also safe for traffic
operation.
• Economical- total cost including initial cost, maintenance
cost and vehicle operation cost should be minimum.
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Factors controlling alignment
Obligatory points
 Traffic
 Geometric design
 Economics
Other considerations
Additional care in hill roads
 Stability
 Drainage
 Geometric standards of hill roads
 Resisting length
2/10/2021 107
Factors controlling alignment cont...
Obligatory points
 Obligatory points through which alignment is to pass
Examples:-bridge site, intermediate town , Mountain pass etc…
 Obligatory points through which alignment should not pass.
Examples:-religious places, costly structure, unsuitable land etc…
Traffic
• origin and destination survey should be carried out in the area
and the desire lines be drawn showing the trend of traffic
flow.
• New road to be aligned should keep in view the desired lines,
traffic flow patterns and future trends.
2/10/2021 108
Geometric design
• Design factors such as gradient ,radius of curve and sight
distance also govern the final alignment of the highway.
• Gradient should be flat and less than the ruling gradient or
design gradient.
• Avoid sudden changes in sight distance, especially near
crossings
• Avoid sharp horizontal curves
• Avoid road intersections near bend
Economy
• Alignment finalised based on total cost including initial cost,
maintenance cost and vehicle operation cost.
Other consideration
• Drainage consideration, political consideration
• Surface water level, high flood level
• Environmental consideration
2/10/2021 109
Topographical control points
• The alignment, where possible should avoid passing
through
 Marshy and low lying land with poor drainage
 Flood prone areas
 Unstable hilly features
Materials and constructional features
 Deep cutting should be avoided
 Earth work is to be balanced; quantities for filling and
excavation
 Alignment should preferably be through better soil area to
minimize pavement thickness
 Location may be near sources of embankment and
pavement materials
2/10/2021 110
Stability
• A common problem in hilly roads is land sliding
• The cutting and filling of the earth to construct the roads on hilly
sides causes steepening of existing slope and affect its stability.
Drainage
• Avoid the cross drainage structure
• The number of cross drainage structure should be minimum.
Geometric standard of hilly road
• Gradient, curve and speed
• Sight distance, radius of curve
Resisting length
• The total work to be done to move the loads along the route taking
horizontal length, the actual difference in level between two stations and
the sum of the ineffective rise and fall in excess of floating gradient.
Should kept as low as possible.
2/10/2021 111
Engineering Surveys for Highway locations
Before a highway alignment is finalised in highway project,
the engineering survey are to be carried out. The various
stages of engineering surveys are
 Map study (Provisional alignment Identification)
 Reconnaissance survey
 Preliminary survey
 Final location and detailed surveys
2/10/2021 112
MAP STUDY
• From the map alternative routes can be suggested in
the office, if the topographic map of that area is
available.
• The probable alignment can be located on the map from
the fallowing details available on the map.
Avoiding valleys, ponds or lake
Avoiding bend of river
If road has to cross a row of hills, possibility of
crossing through mountain pass.
• Map study gives a rough guidance of the routes to be
further surveyed in the field
2/10/2021 113
RECONNAISSANCE SURVEY
• To confirm features indicated on map.
• To examine the general character of the area in field for
deciding the most feasible routes for detailed studies.
• A survey party may inspect along the proposed alternative routes
of the map in the field with very simple instrument like abney
level, tangent clinometer, barometer etc…. To collect additional
details.
• Details to be collected from alternative routes during this
survey are,
 Valleys, ponds, lakes, marshy land, hill, permanent
structure and other obstruction.
 Value of gradient, length of gradient and radius of curve.
2/10/2021 114
RECONNAISSANCE SURVEY cont..
 Number and type of cross drainage structures.
 High Flood Level (HFL)
 Soil Characteristics.
 Geological features.
 Source of construction materials- stone quarries, water
sources.
 Prepare a report on merits and demerits of different
alternative routs.
 As a result a few alternate alignments may be chosen for
further study based on practical considerations observed at
the site.
2/10/2021 115
Preliminary survey
Objective of preliminary survey are:
• To survey the various alternative alignments proposed after the
reconnaissance and to collect all the necessary physical
information and detail of topography, drainage and soil.
• To compare the different proposals in view of the
requirements of the good alignment.
• To estimate quantity of earthwork materials and other
construction aspect and to workout the cost of the alternate
proposals.
Methods of preliminary survey:
a) Conventional approach-survey party carries out surveys using
the required field equipment, taking measurement, collecting
topographical and other data and carrying out soil survey.
2/10/2021 116
Preliminary survey cont…
• Longitudinal and cross sectional profile.
 Plain Terrain` : 100 – 200m
 Rolling Terrain : 50m
 Hilly Terrain : 30m
• Other studies
 Drainage, Hydrological survey, soil survey, Traffic and
Material survey.
b) Modern rapid approach-
By Aerial survey taking the required aerial photographs for
obtaining the necessary topographic and other maps including
details of soil and geology.
• Finalise the best alignment from all considerations by

comparative analysis of alternative routes.
2/10/2021 117
Final location and detailed survey
• The alignment finalised at the design office after the preliminary
survey is to be first located on the field by establishing the
centre line.
Location survey:
• Transferring the alignment on to ground.
• This is done by transit theodolite.
• Major and minor control points are established on the ground
and centre pegs are driven, checking the geometric design
requirements.
• Centre line stacks are driven at suitable intervals, say 50m
interval in plane and rolling terrains and 20m in hilly terrain.
2/10/2021 118
Final location and detailed survey cont..
Detailed survey:
• Temporary bench marks are fixed at intervals of about 250m and at all
drainage and under pass structure.
• Earthwork calculations and drainage details are to be workout from the level
books.
• Cross sectional levels are taken at intervals of 50-100m in Plane terrain, 50-
75m in Rolling terrain, 50m in built-up area, 20m in Hill terrain.
• Detail soil survey is to be carried out.
• CBR value of the soils along the alignment may be determined for design of
pavement.
• The data during detailed survey should be elaborate and complete for
preparing detailed plans, design and estimates of project.
2/10/2021 119
Highway project
• Map study
• Reconnaissance survey
• Preliminary survey
• Location of final alignment
• Detailed survey
• Material survey
• Geometric and structural design
• Earth work
• Pavement construction
• Construction controls
2/10/2021 120
Highway Drawings and Report
 Key map
 Index map
 Preliminary survey plans
 Detailed plan and longitudinal section
 Detailed cross section
 Land acquisition plans
 Drawings of cross drainage and other retaining
structures
 Drawings of road intersections
 Land plans showing quarries etc
2/10/2021 121
Detailed project report preparation
2/10/2021 122
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2/10/2021 130
PPP
• A public–private partnership (PPP) is a government
service or private business venture which is funded and
operated through a partnership of government and one
or more private sector companies. These schemes are
sometimes referred to as PPP, P3 or P3.
2/10/2021 131
PPP
2/10/2021 132
PPP
• PPP involves a contract between a public
sector authority and a private party, in which
the private party provides a public service or
project and assumes substantial financial,
technical and operational risk in the project.
In some types of PPP, the cost of using the
service is borne exclusively by the users of the
service and not by the taxpayer.
2/10/2021 133
PPP
2/10/2021 134
PPP
• In other types (notably the private finance
initiative), capital investment is made by the
private sector on the basis of a contract with
government to provide agreed services and
the cost of providing the service is borne
wholly or in part by the government.
Government contributions to a PPP may also
be in kind (notably the transfer of existing
assets).
2/10/2021 135
PPP
2/10/2021 136
PPP
• In projects that are aimed at creating public
goods like in the infrastructure sector, the
government may provide a capital subsidy
in the form of a one-time grant, so as to
make it more attractive to the private
investors. In some other cases, the government
may support the project by providing revenue
subsidies, including tax breaks or by removing
guaranteed annual revenues for a fixed time
period.
2/10/2021 137
PPP
2/10/2021 138
Government Initiatives in Highways
Some of the recent Government initiatives are as follows:
In April 2020, the Government set a target of constructing roads worth Rs 15 lakh
crore (US$ 212.80 billion) over the next two years.
In May 2020, Border Roads Organisation (BRO) achieved major milestone by
digging up a 440-metre long tunnel below the busy Chamba town on Rishikesh-
Dharasu highway (NH 94).
The Ministry of Road Transport & Highways is expected to award road projects with
a total length of around 4,500 kms worth Rs 50,000 crore (US$ 7.15 billion) in 2020.
To widen and revamp 1.25-lakh km of roads, Government of India has approved the
launch of Phase-III of its rural road programme Pradhan Mantri Gram Sadak Yojana
(PMGSY). PMGSY-III is envisaged to upgrade 1,25,000 kms of road length over the
next five years at an estimated cost of Rs 80,250 crore (US$11.48 billion).
Under the Union Budget 2020-21, the Government has allocated Rs 91,823 crore
(US$ 13.14 billion) under the Ministry of Road Transport and Highways.
Under the Union Budget 2020-21, 30,000 km of PMGSY roads have been built
using Green Technology, Waste Plastic and Cold Mix Technology, thereby reducing
carbon footprint.
139
2/10/2021
Improving the Mobility in rural areas (Expressways and
Village roads)
Poor access to transport in the rural areas of developing countries constrains economic
and social development and contributes to poverty. Improving rural people’s access to
essential services requires improving mobility, through better transport infrastructure
and services and attention to the location, quality, and price of facilities
Elements of physical access

140
2/10/2021
A rural transport system
141
2/10/2021
Bibliography
• Khanna, S. K., & Justo, C. E. G.
Highway engineering. Nem Chand &
Bros.
• IRC Codes.
2/10/2021 142
Thank You
All the Best
2/10/2021 143
2/10/2021 DEPARTMENT OF CIVIL ENGINEERING 1

UNIT-II
INTRODUCTION TO HIGHWAY
GEOMETRIC DESIGN
Malla Reddy Institute of Technology & Science.
2/10/2021 2
Contents
Introduction to Highway Geometric Design; Width of Pavement, Formation and
Land, Cross Slopes etc,
Concept of Friction: Skid and Slip;
Elements of geometric design of highways;
Sight Distances:
Stopping Sight Distance,
Overtaking Sight Distance and
Intermediate Sight Distance;
Horizontal alignment
Design of horizontal curves,
Super elevation,
Extra widening of pavement at curves;
Vertical Alignment:
Gradients,
Compensation in Gradient,
Design of summit curves and valley curves using different
criteria;
Integration of Horizontal and Vertical Curves
2/10/2021 3
IMPORTANCE OF GEOMETRIC DESIGN
• The geometric design of a highway deals with the
dimensions and layout of visible features of the highway
such as alignment, sight distance and intersection.
• The main objective of highway design is to provide optimum
efficiency in traffic operation with maximum safety at
reasonable cost.
• Geometric design of highways deals with following
elements :
Cross section elements
Sight distance considerations
Horizontal alignment details
Vertical alignment details
Intersection elements
2/10/2021 4
Design Controls and criteria
•Design speed
•Topography
•Traffic factors
•Design hourly volume and capacity
•Environmental and other factors
Design speed
• In India different speed standards have been assigned for
different class of road
• Design speed may be modified depending upon the terrain
conditions.
2/10/2021
5
Topography
• Classified based on the general slope of the country.
 Plane terrain- <10%
 Rolling terrain- 10-25%
 Mountainous terrain- 25-60%
 Steep terrain- >60%
Traffic factor
• Vehicular characteristics and human characteristics of road users.
• Different vehicle classes have different speed and
acceleration characteristics, different dimensions and
weight .
• Human factor includes the physical, mental and
psychological characteristics of driver and pedestrian.
2/10/2021 6
Design hourly volume and capacity
• Traffic flow fluctuating with time
• Low value during off-peak hours to the highest
value during the peak hour.
• It is uneconomical to design the roadway for peak
traffic flow.
Environmental factors
Aesthetics
Landscaping
Air pollution
Noise pollution
7
2/10/2021
Pavement surface characteristics
Pavement surface depend on the type of pavement
which is decided based on the,
• Availability of material
• Volume and composition of traffic
• Soil subgrade
• Climatic condition
• Construction facility
• Cost consideration
The important surface characteristics are:
 Friction
 Pavement unevenness
 Light reflecting characteristics
 Drainage of surface water
2/10/2021 8
Friction
• Skidding: when the path travelled along the road surface is more
than the circumferential movement of the wheels due to their
rotation.
• Slipping: when a wheel revolves more than the
corresponding longitudinal movement along the road.
Factors affecting the friction or skid resistance
• Types of pavement surface
• Roughness of pavement
• Condition of the pavement: wet or dry
• Type and condition of tyre
• Speed of the vehicle
• Brake efficiency
• Load and tyre pressure
• Temperature of tyre and pavement
2/10/2021 9
Smooth and worn out tyres offer higher friction factor on dry pavement but new
tyre with good threds gives higher friction factor on wet pavement
 IRC recommended the longitudinal co-efficient of friction

varies 0.35 to 0.4 and lateral co-efficient of friction of 0.15
2/10/2021 10
Pavement unevenness
• Higher operating speed are possible on even surface than
uneven surface.
• It affects,
 Vehicle operation cost
 Comfort and safety
 Fuel consumption
 Wear and tear of tyres and other moving parts
• It is commonly measure by an equipment call “Bump
Integrator”
• Bump integrator is the cumulative measure of vertical
undulations of the pavement surface recorded per unit
horizontal length.
• 250 cm/km for a speed of 100kmph and more than 350 cm/km
considered very unsatisfactory even at speed of 50 kmph.
11
2/10/2021
 Unevenness of pavement surface may be caused by
 In adequate compaction of the fill, subgrade and pavement

layers.
 Un-scientific construction practices including the use of
boulder stones and bricks as soiling course over loose
subgrade soil.
 Use of inferior pavement material.
 Improper surface and subsurface drainage.
 Improper construction machinery.
 Poor maintenance
2/10/2021 12
2/10/2021 13
Light reflecting characteristics
• Night visibility very much depends upon the light reflecting
characteristics of the pavement surface
• The glare caused by the reflection of head light is high on
wet pavement surface than on dry pavement particularly in
case of black top pavement or flexible pavement.
• Light colored or white pavement or rigid pavement surface
give good visibility at night particularly during the rain, and
produces glare or eye strain during bright sunlight.
2/10/2021 14
Highway cross section elements
• Carriageway • Side slope
• Shoulder • Kerb
• Roadway width • Guard rail
• Right of way • Side drain
• Building line • Other
• Control line facilities
• Median
• Camber/ cross slope
• Crown
2/10/2021 15
Carriageway:
• It is the travel way which is used for movement of vehicle, it
takes the vehicular loading .
• It may be cement concrete road or bituminous pavement.
• Width of carriageway is determined on the basis of the width of
the vehicle and the minimum side clearance for safety.
• As per IRC specification, the maximum width of vehicle is
2.44m,minimum clearance of 0.68 in case of single lane and
1.02m in case of double lane.
2/10/2021 16
WIDTH OF CARRIAGEWAY
SL. Class of road Width of carriageway

NO. in ‘m’
1 Single lane 3.75
2 Two lane without raised kerbs 7.0
3 Two lane with raised kerbs 7.5
4 Intermediate lane 5.5
5 Multilane pavement 3.5/lane
2/10/2021 17
WIDTH OF ROADWAY OF VARIOUS CLASSES
OF ROADS
SL. No. Road classification Roadway wisth
Plane and rolling Mountainous and

terrain steep
terrain
1 NH & SH
a) Single lane 12 6.25
b) two lane 12 6.25
2 MDR
a) Single lane 9 4.75
b) two lane 9 4.75
3 ODR
a) Single lane 7.5 4.75
b) two lane 9 4.75
4 Village roads-single lane 7.5 4
2/10/2021 18
Two lane two-way road
carriageway
2/10/2021 19
Shoulder:
• It is provided along the road edge to serve as an
emergency lane for vehicle.
• It act as a service lane for vehicles that have broken
down.
• The minimum shoulder width of 4.6 m so that a truck
stationed at the side of the shoulder would have a clearance
of 1.85m from the pavement edge.
• IRC recommended the minimum shoulder width is 2.5 m
• It should have sufficient load bearing capacity even in wet
weather.
• The surface of the should be rougher than the traffic lanes
so that vehicles are discouraged to use the shoulder as a
regular traffic.
• The colour should be different from that of the
pavement so as to be distinct.
2/10/2021 20
shoulder
Cycle track
Footpath
2/10/2021 21
Treated
unTreated shoulder
shoulder
2/10/2021 22
Width of the roadway or formation width:
• It is the sum of the width of the carriageway or pavement
including separators if any and the shoulders.
Right of way:
• It is the total area of land acquired for the road along its
alignment.
• It depends on the importance of the road and possible
future development.
• It is desirable to acquire more width of land as the cost of
adjoining land invariably increases very much , soon after the
new highway is constructed.
2/10/2021 23
Building lane:
• In order to reserve sufficient space for future development of
roads, It is desirable to control the building activities on either
side of the road boundary, beyond the land width acquired for the
land.
Control lines:
• In addition to “building line”, it is desirable to control the nature
of building upto further “set back distance” .
2/10/2021 24
Traffic separators or median:
• The main function is to prevent head on collision
between the vehicle moving in opposite direction.
• Channelize traffic into streams at intersection.
• Segregate slow traffic and to protect pedestrians.
• IRC recommends a minimum desirable width of 5 m
and may be reduce to 3 m where land is restricted.
• The minimum width of median in urban area is
1.2m.
2/10/2021 25
4-lane divided carriage way or dual carriage way
Median/
separator
2/10/2021 26
Cross slope or camber:
• It is the slope provided to the road surface in the
transverse direction to drain off the rain water
from the road surface.
• Toprevent the entry of surface water into the
subgrade soil through pavement.
• Toprevent the entry of water into the bituminous
pavement layer.
• Toremove the rain water from the pavement
surface as quick as possible and to allow the
pavement to get dry soon after the rain.
• It is expressed as a percentage or 1V:Nh.
• It depends on the pavement surface and amount
of rainfall.
2/10/2021 27
Shape of the cross slope:
• Parabolic shape(fast moving vehicle)
• Straight line
• Combination of parabolic and straight line
Recommended values of camber for different types of road
surface
Sl no. Type of road surface Range of camber in areas of
rain
fall range
heavy light
1 Cement concrete and high type 1 in 50(2%) 1 in 60(1.7%)
bituminous pavement
2 Thin bituminous surface 1 in 40(2.5%) 1 in 50(2%)
3 Water bound macadam(WBM) and gravel I in 33(3%) 1 in 40(2.5%)
pavement
4 Earth 1 in 25(4%) 1 in 33(3%)
2/10/2021 28
Too steep slope is not desirable because of the fallowing reasons
• Uncomfortable side thrust and unequal wear of the tyres as well as road
surface.
• Problem of toppling over highly laden bullock cart and truck.
• Tendency of most of vehicle travel along the centre line.
Kerb:
• It indicates the boundary between the pavement and shoulder.
• It is desirable to provide kerbs in urban areas.
• It is of three types
1-Low or mountable kerb:
• It allow the driver to enter the shoulder area with little difficulty.
• The height of the this type of shoulder kerb is about 10 cm above the
pavement edge with slope to help the vehicle climb the kerb easily.
2/10/2021 29
2-Semi-barrier kerb:
• It is provided on the periphery of a roadway where the
pedestrian traffic is high.
• Height of about 15 cm above the pavement edge with a
batter of 1:1 on the top 7.5 cm.
• It prevents parking the vehicle but during emergency it is
possible to drive over this kerb with some difficulty.
3-Barrier type kerb:
• It is provided in built-up area adjacent to the foot paths with
considerable pedestrian traffic.
• The height of the kerb is about 20 cm above the pavement
edge with a steep batter of 1V:0.25H.
2/10/2021 30
kerb
2/10/2021 31
Guard rail
• It is provided at the edge of the shoulder

when the road is constructed on a fill exceeds
3 m.
• It is also provided on horizontal curve so as to
provide a better night visibility of the curves
under the head light of the vehicle.
2/10/2021 32
2/10/2021 33
Road margins
Parking lane:
• These are provided on urban roads to allow kerb parking
• As far as possible only parallel parking should be allowed as it
is safer for moving vehicle.
•It should have sufficient width say 3m Lay
bay:
• These are provided near the public conveniences with guide
map to enable driver to stop clear off the carriageway.
• It has 3m width,30m length with 15m end tapers on both sides.
Bus bays:
• These may be provided by recessing the kerb to avoid
conflict with moving traffic.
• It is located atleast 75m away from the intersection.
2/10/2021 34
Frontage road:
• These are provided to give access to properties along an important
highway with control access to express way or free way
• It may run parallel to the highway and are isolated by separator.
Driveway:
• It connect the highway with commercial establishment like fuel stations,
service stations etc…
• It should be located away from the intersection.
Cycle track:
• It provided in urban areas when the volume of cycle traffic on the road
is very high.
• A minimum width of 2m is provided for cycle track.
Footpath:
• These are provided in urban areas when the vehicular as well as
pedestrian traffic are heavy.
• To protect the pedestrian and decrease accident.
• Minimum width of 1.5m is provided.
2/10/2021 35
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Frontage
road
2/10/2021 38
c/s of highway in hilly area
2/10/2021 39
c/s of road in built-up area
2/10/2021 40
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c/s of road in cutting
2/10/2021 43
2/10/2021 44
Sight Distance
&
Horizontal Alignment
2/10/2021 45
SIGHT DISTNCE
• Sight distance available from a point is the actual distance
along the road surface, which a driver from a specified
height above the carriageway has visibility of stationary or
moving objects. OR
• It is the length of road visible ahead to the driver at any
instance.
2/10/2021 46
Types of sight distance
• Stopping or absolute minimum sight
distance(SSD)
• Safe overtaking or passing sight distance (OSD)
• Safe sight distance for entering into uncontrolled
intersection.
• Intermediate sight distance
• Head light sight distance
2/10/2021 47
Stopping sight distance:
• The minimum sight distance available on a highway at any spot should be of
sufficient length to stop a vehicle traveling at design speed, safely without
collision with any other obstruction.
Over taking sight distance:
• The minimum distance open to the vision of the driver of a vehicle intending to
overtake slow vehicle ahead with safety against the traffic of opposite direction
is known as the minimum overtaking sight distance (OSD) or the safe passing
sight distance.
Sight distance at intersection:
• Driver entering an uncontrolled intersection (particularly unsignalised
Intersection) has sufficient visibility to enable him to take control of his
vehicle and to avoid collision with
another vehicle.
2/10/2021 48
Intermediate sight distance:
• This is defined as twice the stopping sight distance.
When overtaking sight distance can not be provided,
intermediate sight distance is provided to give
limited overtaking opportunities to fast vehicles.
Head light sight distance:
• This is the distance visible to a driver during night
driving under the illumination of the vehicle head
lights. This sight distance is critical at up-gradients
and at the ascending stretch of the valley curves.
2/10/2021 49
Stopping Sight Distance
• SSD is the minimum sight distance available on a highway at any

spot having sufficient length to enable the driver to stop a vehicle
traveling at design speed, safely without collision with any other
obstruction.
It depends on:
• Feature of road ahead
• Height of driver’s eye above the road surface(1.2m)
• Height of the object above the road surface(0.15m)
2/10/2021 50
Criteria for measurement
• Height of driver’s eye above road surface (H)
• Height of object above road surface(h)
H
h
IRC
• H = 1.2m
• h = 0.15m
2/10/2021 51
Factors affecting the SSD
•Total reaction time of driver
•Speed of vehicle
•Efficiency of brakes
•Frictional resistance between road and tyre
•Gradient of road
Total reaction time of driver:
• It is the time taken from the instant the object is visible to the
driver to the instant the brake is effectively applied, it divide into
types
1. Perception time
2. Brake reaction time
2/10/2021 52
Perception time:
• it is the time from the instant the object comes on the line of
sight of the driver to the instant he realizes that the vehicle
needs to be stopped.
Brake reaction time:
• The brake reaction also depends on several factor including
the skill of the driver, the type of the problems and various
other environment factor.
• Total reaction time of driver can be calculated by “PIEV”
theory
2/10/2021 53
“PIEV” Theory
Total reaction time of driver is split into four parts:
• P-perception
• I-intellection I-
E
• E-Emotion
• V-Volition P V
2/10/2021
54
perception
• It is the time required for the sensation received by the eyes
or ears to be transmitted to the brain through the nervous
system and spinal chord.
Intellection:
•It is the time required for understanding the situation.
Emotion:
• It is the time elapsed during emotional sensation and
disturbance such as fear, anger or any other emotional feeling
such as superstition etc, with reference to the situation.
Volition:
• It is the time taken for the final action
Total reaction time of driver may be vary from 0.5 sec to 4 sec
2/10/2021 55
Analysis of SSD
• The stopping sight distance is the sum of lag
distance and the braking distance.
Lag distance:
• It is the distance, the vehicle traveled during the reaction time
• If ‘V’ is the design speed in m/sec and ‘t’ is the total reaction
time of the driver in seconds,
lag distance = v.t metres. Lag distance=0.278 V.t
Where “v” in m/sec meters Where “v” in Kmph,
t=2.5 sec T= time in sec=2.5 sec
2/10/2021 56
Braking distance :
• It is the distance traveled by the vehicle after the application
of brake. For a level road this is obtained by equating the
work done in stopping the vehicle and the kinetic energy of
the vehicle.
• work done against friction force in stopping the vehicle is F x
l = f W l, where W is the total weight of the vehicle.
• The kinetic energy at the design speed of v m/sec will be ½
m. v²
2/10/2021 57
Braking distance= v²/2gf
SSD=lag distance + braking distance
SSD=0.278V.t + v²/254f
Coefficient of longitudinal friction

Speed, kmph 30 40 50 60 ˃80
Longitudinal
coefficient of 0.40 0.38 0.37 0.36 0.35
friction
• Two-way traffic single lane road: SSD=2*SSD

• In one-way traffic with single or more lane or two- way traffic with
more than single lane: Minimum SSD= SSD
2/10/2021
58
OVERTAKING SIGHTDISTANCE
The minimum distance open to the vision of the driver of a vehicle intending to
overtake slow vehicle ahead with safety against the traffic of opposite direction is
known as the minimum overtaking sight distance (OSD) or the safe
passing sight distance.
• The overtaking sight distance or OSD is the distance measured along the centre of
the road which a driver with his eye level 1.2 m above the road surface can see the
top of an object 1.2 m above the road surface
2/10/2021 59
Factors affecting the OSD
• speeds of
 overtaking vehicle
 overtaken vehicle
 the vehicle coming from opposite direction, if any.
• Distance between the overtaking and
overtaken vehicles.
• Skill and reaction time of the driver
• Rate of acceleration of overtaking vehicle
• Gradient of the road
2/10/2021 60
Analysis of OSD
• Fallow the Fig. 4.14, p-96 of highway engineering by S.K. Khanna and
C.E.G. Justo
• d1 is the distance traveled by overtaking vehicle
“A” during the reaction time t sec of the driver
from position A1 to A2.
• D2 is the distance traveled by the vehicle A from A2 to
A3 during the actual overtaking operation, in time T
sec.
• D3 is the distance traveled by on-coming vehicle C
from C1 to C2 during the over taking operation of A,
i.e. T sec.
• B is the overtaken or slow moving vehicle.
2/10/2021 61
Cont…
• B is the overtaken or slow moving vehicle moving
with uniform speed Vb m/sec or Vb Kmph;
• C is a vehicle coming from opposite direction at
the design speed V m/sec or V kmph
• The distance traveled by the vehicle A during this
reaction time is d1 and is between
the positions A1 and A2. this distance will be
equal to Vb.t meter
• where t is the reaction time of the driver in
second= 2 sec.
2/10/2021 62
OSD = d1+ d2+ d3
OSD = 0.28 Vb. t +0.28Vb .T + 2s + 0.28 V.T
S = SPACING OF VEHICLES = (0.2 V b+ 6)
T= √ 4x3.6s / A = √ 14.4s /A
If the speed of the overtaken vehicle is not given

Vb=(V-16) kmph, where V= speed of overtaking vehicle in kmph
The minimum overtaking sight distance = d1+d2+d3 for two-way traffic.

On divide highways and on roads with one way traffic regulation, the
overtaking distance = d1+d2 as no vehicle is
expected from the opposite direction .
2/10/2021
63
Overtaking Zones
• It is desirable to construct highways in such a way that the length of road visible
ahead at every point is sufficient for safe overtaking. This is seldom practicable
and there may be stretches where the safe overtaking distance cannot be
provided. But the overtaking opportunity for vehicles moving at design speed
should be given at frequent intervals. These zones which are meant forever
taking are called overtaking zones.
• The minimum length of overtaking zone should be three time the safe
overtaking distance i.e., 3 (d1+d2) for one- way roads and 3(d1+d2+d3) for
two-way roads.
• Desirable length of overtaking zones is kept five times the overtaking sight
distance. i.e., 5(d1+d2) for one-way roads and 5(d1+d2+d3) for two-way roads.
2/10/2021
64
2/10/2021 65
DESIGN
OF
HORIZONTAL ALIGNMENT
2/10/2021 66
2/10/2021 67
Horizontal Curves
• A horizontal highway curve is a curve in plan to
provide change in direction to the central line of a
road. When a vehicle traverses a horizontal curve,
the centrifugal force acts horizontally outwards
through the centre of gravity of the vehicle.
• P = W v²∕gR
• Where,
• P = centrifuge force, kg
• W = weight of the vehicle, kg
• R = radius of the circular curve, m
• v = speed of vehicle, m/sec
• g = acceleration due to gravity = 9.8 m/sec
2/10/2021
68
P=mv²/gR
h
A B
W F
2/10/2021 69
Cont…..
• P/W is known as the centrifugal ratio or the impact factor. The
centrifuge ratio is thus equal to v²∕gR
• The centrifugal force acting on a vehicle negotiating a
horizontal curve has two effects
 Tendency to overturn the vehicle outwards about the outer wheels
 Tendency to skid the vehicle laterally, outwards
Overturning effect
• The equilibrium condition for overturning will occur when Ph =
Wb/2, or when P/W = b/2h. This means that there is danger of
overturning when the centrifugal when the centrifugal ratio P/W
or v²/gR attains a values of b/2h.
2/10/2021 70
Transverse skidding effect
• P = FA+ FB= f(RA+RB) =fW
• Since P = f W, the centrifugal ratio P/W is equal to ‘f ‘. In
other words when the centrifugal ratio attains a value equal to
the coefficient of lateral friction there is a danger of lateral
skidding.
• Thus to avoid overturning and lateral skidding on a
horizontal curve, the centrifugal ratio should always be less
than b/2h and also ‘f’
• ‘f’ is less than b/2h.-The vehicle would skid and not
overturn
• b/2h is lower than ‘f’-The vehicle would overturn on the
outer side before skidding
2/10/2021 71
Superelevation
• In order to counteract the effect of centrifugal force and to
reduce the tendency of the vehicle to overturn or skid, the outer
edge of the pavement is raised with respect to the inner edge,
thus providing a transverse slope throughout the length of the
horizontal curve, this transverse inclination to the pavement
surface is known as Superelevation or cant or banking.
• The Superelevation ‘e’ is expressed as the ratio of the height
of outer edge with respect to the horizontal width.
2/10/2021 72
E=eB
B
2/10/2021 73
2/10/2021 74
Analysis of Superelevation
• The force acting on the vehicle while moving on a
circular curve of radius R meters, at speed of v m/sec
are
• The centrifugal force P = Wv²/gR acting horizontal
outwards through the centre of gravity, CG
• The weight W of the vehicle acting vertically
downloads through the CG
• The frictional force developed between the wheels and
the pavement counteractions transversely along the
pavement surface towards the centre
of the curve
2/10/2021 75
Superelevation cont…
 WV 2  WV 2
W sin   f  W co s   sin    c os 
 2
gR  gR
OR V
ta n   f  1 f tan  
gR
Dividing Cos α on both sides
OR e f 
V 2
1  f e (1-fe)=1-0.15x.o7=0.99≈1
gR
2
OR R  V
g  f  e
2
V
OR e f  OR e f 
V 2
gR 127 R
V in m/Sec V in kmph
Rin ‘m’ Rin‘m’
2/10/2021 76
Cont
…
• e = rate of Superelevation = tan Ө
• f = design value of lateral friction coefficient
= 0.15
• v = speed of the vehicle, m/sec
• R = radius of the horizontal curve, mg
= acceleration due to gravity = 9.8
m/sec²
2/10/2021 77
Maximum Superelevation
• In the case of heavily loaded bullock carts and trucks carrying less dense
materials like straw or cotton, the centre of gravity of the loaded vehicle will be
relatively high and it will not be safe for such vehicles to move on a road with a
high rate of Superelevation. Because of the slow speed, the centrifugal force will
be negligibly small in the case of bullock carts. Hence to avoid the
danger of toppling of such loaded slow moving vehicles, it is essential to limit
the value of maximum allowable Superelevation.
• Indian Roads Congress had fixed the maximum limit of Superelevation in
plan and rolling terrains and is snow bound areas as 7.0 %.
• On hill roads not bound by snow a maximum Superelevation upto
10% .
• On urban road stretches with frequent intersections, it may be necessary to
limit the maximum Superelevation to 4.0 %.
2/10/2021 78
Minimum Superelevation
• From drainage consideration it is necessary to have a

minimum cross to drain off the surface water. If the
calculated Superelevation is equal to or less than the
camber of the road surface, then the minimum
Superelevation to be provided on horizontal curve
may be limited to the camber of the surface.
2/10/2021 79
Design ofSuperelevation
• Step-1: The Superelevation for 75 percent of design speed (v
m/sec/kmph) is calculated neglecting the friction.
V2
(0.75V )2 e
e
127R 225R
• Step-2: If the calculated value of ‘e’ is less than 7% or 0.07 the value
so obtained is provided. If the value of ‘e’ as step-1 exceeds 0.07 then
provides maximum Superelevation equal to 0.07 and proceed with step-
3 or 4.
• Step-3: Check the coefficient of friction of friction developed for the
maximum value of e =0.07 at the full value of design speed.
V2
f 0.07
127R
• If the value of f thus calculated is less than 0.15 the Superelevation of
0.07 is safe for the design speed. If not, calculate the restricted speed as
given in step -4.
2/10/2021 80
Cont….
• Step-4 The allowable speed (Va m/sec. or Va Kmph) at The
curve is calculated by considering the design coefficient of
lateral friction and the maximum Superelevation.
• e+f=0.07+0.15=va²/127R
• If the allowed speed, as calculated above is higher than the
design speed, then the design is adequate and provides a
Superelevation of ‘e’ equal to 0.07.
• If the allowable speed is less than the design speed, the speed is
limited to the allowed speed Va kmph calculated above and
Appropriate warning sign and speed limit regulation sign are
installed to restrict and regulate the speed.
2/10/2021 81
Attainment of superelevation
Split-up into two parts::

•Elimination of crown of the cambered section
•Rotation of pavement to attain full superelevation
Elimination of crown of the cambered section
1st Method: Outer edge rotated about the crown
2/10/2021 82
Disadvantages
• Small length of road – cross slope less than
camber
• Drainage problem in outer half
2nd Method: Crown shifted outwards
Disadvantages
• Large negative superelevation on outer half
• Drivers have the tendency to run the vehicle along shifted crown
2/10/2021 83
Rotation of pavement to attain full superelevation

1st Method: Rotation about the C/L (depressing the inner edge and raising the
outer edge each by half the total amount of superelevation)
Advantages
• Earthwork is balanced
• Vertical profile of the C/L remains unchanged
Disadvantages
• Drainage problem: depressing the inner edge
below the general level
2/10/2021 84
2nd Method: Rotation about the Inner edge (raising both the centre as well as
outer edge – outer edge is raised by the total amount of superelevation)
Advantages
• No drainage problem
Disadvantages
• Additional earth filling
• C/L of the pavement is also raised (vertical alignment of the
road is changed)
2/10/2021 85
Radiusof Horizontal Curve
• The ruling minimum radius of the curve for ruling design speed v
m/sec. or Vkmphis given by.
V2
RRulling 
127(e  f )
• According to the earlier specifications of the IRC, the ruling
minimum radius of the horizontal curve was calculated from a
speed value, 16 kmph higher than the design speed i,e., (V+16)
kmph.
2/10/2021
86
Widening of Pavement on Horizontal Curves
• On horizontal corves, especially when they are not of very large
radii, it is common to widen the pavement slightly more than the
normal width,
• Widening is needed for the following reasons :
 The driver experience difficulties in steering around the curve.
 The vehicle occupies a greater width as the rear wheel don’t track the
front wheel. known as ‘Off tracking’
 For greater visibility at curve, the driver have tendency not to follow the
central path of the lane, but to use the outer side at the beginning of the
curve.
 While two vehicle cross or overtake at horizontal curve there is
psychological tendency to maintain a greater clearance between the
vehicle for safety.
2/10/2021 87
Off tracking
• An automobile has a rigid wheel base and only the
front wheels can be turned, when this vehicle takes a
turn to negotiate a horizontal curve, the rear wheel
do not follow the same path as that of the front
wheels. This phenomenon is called off tracking.
• The required extra widening of the pavement at the
horizontal curves depends on the length of the wheel
base of the vehicle ‘l’, radius of the
curve ‘R’ and the psychological factors.
2/10/2021 88
Analysis of extra widening on curves
• It is divided into two parts;
 Mechanical widening (Wm): the widening required to account
for the off tracking due to the rigidity of wheel base is called
mechanical widening
 Psychological widening (Wps): extra width of the pavement
is also provided for psychological reasons such as , to
provide for greater maneuverability of steering at high
speed, to allow for the extra space for overhangs of vehicles
and to provide greater clearance for crossing and
overturning vehicles on curve.
• Total widening W = Wps+ Wm
2/10/2021 89
Mechanical Widening
Wm = R2 – R1 Wm
From Δ OAB, OA2 = OB2 –

B R1
BA2 R12 = R22 – l2
l R2
C
A O
(R2 – Wm)2 = R22 – l2
l2 = Wm (2 R2 – Wm)
Wm = l2 / (2 R2 – Wm)
Wm = l2 / 2 R (Approx.) or
Wm=nl²/2R
2/10/2021 90
Where, R = Mean radius of the curve in m, n=no. of
traffic lanes
R = Mean radius of the curve, m
l = Length of Wheel base of longest vehicle , m ( l = 6.0 m or
6.1m for commercial vehicles)
V= design speed, kmph
2/10/2021 91
Psychological Widening
V
W Ps
9.5 R (Empirical formula)
V = Design speed of the vehicle, km/h R
= Radius of the curve, m
Total extra widening = Mechanical widening
+Psychological Widening
2
nl V
W e
2 R 9.5 R
2/10/2021 92
Method of introducing extrawidening
• With transition curve: increase the width at an approximately
uniform rate along the transition curve - the extra width should be
continued over the full length of circular curve
• Without transition curves: provide two-third widening on

tangent and the remaining one-third on the circular curve
beyond the tangent point
• With transition curve: Widening is generally applied
equally on both sides of the carriageway
• Without transition curve: the entire widening should be done
on inner side
• On sharp curves of hill roads: the entire widening should be done
on inner side
2/10/2021 93
Method of introducing extrawidening
Follow Fig- 4.27, p-123
2/10/2021 94
2/10/2021 95
Horizontal transition curves
• When a non circular curve is introduce between a straight and a
circular curve has a varying radius which decreases from infinity
at the straight end (tangent point) to the desired radius of the
circular curve at the other end (curve point) for the gradual
introduction of centrifugal force is known as transition curve.
Straight curve
Circular curve
2/10/2021 96
Objectives for providing transition curve
 To introduce gradually the centrifugal force between the tangent point
and the beginning of the circular curve, avoiding sudden jerk on the
vehicle. This increases the comfort of passengers.
 To enable the driver turn the steering gradually for his own comfort and
security
 To provide gradual introduction of super elevation
 To provide gradual introduction of extra widening.
 To enhance the aesthetic appearance of the road.
2/10/2021 97
Type of transition curve
• spiral or clothoid
• cubic parabola Follow the Fig-4.29, p-126 of highway
• Lemniscate Engineering by S.K. Khanna and C.E.G.
Justo
• IRC recommends spiral as the transition curve
because it fulfills the requirement of an ideal
transition curve, that is;
 rate of change or centrifugal acceleration is
consistent
 Radius of the transition curve is infinity at the straight edge
and changes to R at the curve point (Ls ᾳ1/R)and calculation
and field implementation is very easy.
2/10/2021 98
Length of transition curve
• Case-1:Rate of change of centrifugal acceleration
LS = 0.0215V 3
CR
80
C= 0.5 < C < 0.8
(75 +V )
• Where,
 Ls= length of transition curve in ‘m’
 C= allowable rate of change of centrifugal accleration, m/ sec²
 R= Radius of the circular curve in ‘m’
2/10/2021 99
case-2:Rate of introduction of super-elevation
• If the pavement is rotated about the center line.
Ls=EN/2=eN/2(W+We)
• If the pavement is rotated about the inner edge
Ls= EN= eN(W+We)
• Where W is the width of pavement

• We is the extra widening
• Rate of change of superelevation of 1 in N
2/10/2021 100
case-3:By empirical formula
• According to IRC standards:
 For plane and rolling terrain:
2.7V 2
LS =
R
 For mountainous and steep terrain:
V2
LS =
R
The design length of transition curve(Ls) will be the highest value of
case-1,2 and 3
2/10/2021 101
Shift of the transition curve
Shift of the transition curve ‘S’
2
Ls
S =
24R
2/10/2021 102
Set-back distance on horizontal curve
Where there are sight obstruction like
buildings, cut slope or trees on the inner sides SSD
of the curves, either the obstruction should be
removed or the alignment should be changed
in order to provide adequate sight distance.
If it is not possible to provide adequate sight m’

distance on the curves on existing roads,
regulatory sign should be installed to control
the traffic suitably. clearance distance or set-
back distance is the distance required from the
centre line of a horizontal curve to an obstruct Obstruction R
on the inner side adequate sight distance of the
of the curve to provide
2/10/2021 103
Case-I: if length of curve (Lc ) > sight distance(S)
m'  R  (R  d ) cos
 '
2
'  180S
Where,
2 2 ( R  d )
M’ = set-back distance
d = the distance between the centre line of the road and the centre line of the inside lane
in ‘m’
R = radius of the curve in ‘m’
α = angle subtended by the arc length ‘S’ at the centre
2/10/2021 104
Case-II: if length of curve (Lc ) < sight distance(S)

m'  R  (R  d ) cos 
' S  LC
Sin
 '
2 2 2
'  180LC
2 2 ( R  d )
Where ‘Lc’ is the length of curve and ‘S’ is the sight distance
2/10/2021 105
Problem
106
2/10/2021
Problem Cont…
107
2/10/2021
Curve resistance
The automobiles are steered by turning the
front wheels, but the rear wheels do not turn.
When a vehicle driven by rear wheels move
on a horizontal curve, the direction of
rotation of rear and front wheels are
different and so there is some losses in the
tractive froce.
thus the loss of tractive force due to

turning of a vehicle on a horizontal curve
, which is termed as curve resistance will be
equal to (T- T cos α) or T (1-cos α) and will
depend on turning angle α
2/10/2021 108
Vertical Alignment
2/10/2021 109
Vertical alignment
The vertical alignment is the elevation or profile of the centre line of the road.
The vertical alignment consist of grade and vertical curve and it influence the
vehicle speed, acceleration, sight distance and comfort in vehicle movements at
high speed.
2/10/2021
110
Gradient
• It is the rate of rise or fall along the length of the road with respect to the
horizontal. It is expressed as a ratio of 1 in x (1 vertical unit to x horizontal
unit). Some times the gradient is also expressed as a percentage i.e. n% (n in
100).
• Represented by:
+n % + 1 in X (+ve or Ascending) or -n%

- 1 in X (-ve or descending)
valley
summit
2/10/2021 111
Typical Gradients (IRC)
• Ruling Gradient
• Limiting Gradient
• Exceptional gradient
• Minimum Gradient
• Ruling gradient (design gradient):
• It is the maximum gradient within which the designer attempts to design the
vertical profile of road, it depends on
 Type of terrain
 Length of grade
 Speed
 Pulling power of vehicles
 Presence of horizontal curves
 Mixed traffic
2/10/2021 112
Limiting Gradient:
• Steeper than ruling gradient. In hilly roads, it may be frequently
necessary to exceed ruling gradient and adopt limiting gradient, it
depends on
 Topography
 Cost in constructing the road
Exceptional Gradient:
• Exceptional gradient are very steeper gradients given at
unavoidable situations. They should be limited for short
stretches not exceeding about 100 m at a stretch.
2/10/2021 113
critical length of the grade:
• The maximum length of the ascending gradient which a loaded truck can operate
without undue reduction in speed is called critical length of the grade. A speed of
25 kmph is a reasonable value. This value depends on the size, power, load,
initial speed.
Minimum gradient
• This is important only at locations where surface drainage is important. Camber
will take care of the lateral drainage. But the longitudinal drainage along the side
drains require some slope for smooth flow of water. Therefore minimum
gradient is provided for drainage purpose and it depends on the rain fall, type of
soil and other site conditions.
• A minimum of 1 in 500 may be sufficient for concrete drain and 1 in 200 for
open soil drains.
2/10/2021 114
Value of gradient as per IRC
Terrain Ruling Limiting Exceptional
gradient gradient gradient
Plain and Rolling 3.3% 5% 6.70%
(1 in 30)
Mountainous terrain 5% 6% 7%
(1 in 20)
Steep terrain up to 5% 6% 7%
3000m (MSL) (1 in 20)
6% 7% 8%
(1 in 16.7)
Steep terrain ( >3000m)
2/10/2021 115
SUMMIT CURVE
Length of summit curve(L) for SSD
• Case-1(L >SSD)
NS 2 NS 2
L 
 2
or L
2H  2h 4.4
• Case-2(L <SSD)
L 2S 
2H  2h
2
or L  2S 
4.4
N N
2/10/2021 116
length of summit curve for OSD
• Case-1(L >OSD)
2
NS 2 NS
L  or L
8H 9.6
• Case-2(L <OSD)
8H 9.6
L  2S  or L  2S 
N N
S=sight distance i.e. SSD, OSD or ISD
N=deviation angle
i.e. algebraic difference between two grade
H=height of driver eye above the carriageway i.e. 1.2 m h=height of
driver eye above the carriageway i.e. 0.15 m
2/10/2021 117
VALLEY CURVE
Length of valley curve for comfort condition:
1
  V 
3
 2
 N    OR
L  2   3.6  
L  0.38 NV 
 C  1
  3 2
 
N= deviation angle i.e. algebraic difference between two grade

C= rate of change of centrifugal acceleration may be taken as 0.6 m/sec³
V= speed of vehicle in kmph
2/10/2021 118
Length of valley curve for head light sight distance
• Case-1(L > SSD)
NS 2 NS 2
L OR
L
2h1  2S tan   1.5  0.035S 
• Case-2(L <SSD)
2h1 2S tan  L  2S 
1.5 0.035S 
L  2S  OR
N N
h1=height of head light above the carriesway
α= inclination of focused portion of the beam of light w.r.t horizontal or beam angle .
N= deviation angle i.e. algebraic difference between two grade.
S=head light distance is equal to SSD
2/10/2021 119
Grade compensation
• At the horizontal curve ,due to the turning angle α of the
vehicle, the curve resistance develop is equal to T(1-Cos
α). When there is a horizontal curve in addition to the
gradient, there will be a increase in resistance to fraction
due to both gradient and curve. It is necessary that in
such cases the total resistance due to grade and the curve
should not exceeded the resistance due to maximum
value of the gradient specified.
• Maximum value generally taken as ruling gradient
2/10/2021
120
Cont…
• Thus grade
. be defined as the
compensation can
reduction in gradient at the horizontal curve because of
the additional tractive force required due to curve
resistance (T−Tcosα), which is intended to offset the
extra tractive force involved at the curve.
• IRC gave the following specification for the grade
compensation.
1. Grade compensation is not required for grades flatter than 4%
because the loss of tractive force is negligible.
2. Grade compensation is (30+R)/R %, where ‘R’ is the radius of
the horizontal curve in meters.
3. The maximum grade compensation is limited to 75/R%.
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2/10/2021 1
UNIT-III
Traffic Engineering & Regulations
By Mr. M. Gnanendra Babu

2/10/2021 2
• Course Outcome: : At the end of the course, the student will
be able to Design highway geometrics.
• Text Books:
1. Highway Engineering – S. K. Khanna & C. E. G. Justo,
Nemchand & Bros., 7th edition (2000).
2. Traffic Engineering & Transportation Planning – Dr. L. . Kadyali,
Khanna Publications – 6th Edition – 1997.
2/10/2021 3
• References:
1. Principles of Traffic and Highway Engineering – Garber
& Hoel, Cengage Learning.
2. Principles and Practices of Highway Engineering – Dr. L.
R. Kadiyali and Dr. N. B Lal - Khanna Publications.
3. Highway Engineering – S. P. Bindra , Dhanpat Rai &
Sons. – 4th Edition (1981)
4. IRC 37-2012 : Tentative guidelines for design of flexible
pavement
5. IRC 58-2011: Guidelines for design of plain jointed rigid
pavements.
6. IRC 81-1997 : Guidelines for design of overlay using B
enkalman Beam Deflection Technique
2/10/2021 4
Topics Included
Topics
1.Importance of Geometric Design.
2. Design controls and Criteria.
3. Highway Cross Section Elements – Sight Distance
Elements- Stopping Sight Distance.
4. Overtaking Sight Distance and Intermediate Sight Distance
5. Design of Horizontal Alignment
6. Design of Super elevation and Extra widening
7. Design of Transition Curves
8. Design of Vertical alignment
9. Gradients
10. Vertical curves.
2/10/2021 5
Basic parameters of traffic flow
•Traffic flow
–Complex movements
–Stochastic in nature
•Traffic Engineering
–Control and management of facilities
–By modeling driver, vehicle, road,
and environmental conditions
Traffic stream parameters
•Measures
–Quantitative (for modeling)
–Qualitative (for evaluation)
•Characteristics
–Macroscopic
–Microscopic
•Fundamental parameters
–Speed
–Flow
–Density
•Derived parameters
–Time headway
–Space headway
–Travel time
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Objectives of Traffic Engineering
–To achieve smooth and easy flow of traffic at intersections
–To develop the methods for improvement in general and
solving specific problems in particulars.
–To have safe, convenient, comfort, and economic transport of
goods and persons
–To improve speed of vehicles.
–To increase traffic capacity of roads.
–To make the streets safe for movements of both pedestrians
and vehicles.
–To reduce the delay in road journey.
–To reduce the chance for roads accidents to minimum
2/10/2021 8
Flow Or Volume : Flow can be defines as the
No.of vehicles passing through a point during a
period of time.
It is denoted by ‘Q’ or ‘q’
Q=n/t
where n= No.of vehicles
T= Time
2/10/2021 9
Density or Concentration: Density can be
defined as the no .of vehicles passing over
a unit length of highway at an instant of
time.
It can be expressed as vehicles/mile
It is denoted by ‘K’
K=n/L vehicles/mile
where n= No.of vehicles
L= Length of miles
1 mile= 1.609km
2/10/2021 10
SpeedSpeed is defined as the distance travelled a
vehicle during a unit of time
It can be expressed in mile/hour, km/hr
It is denoted by ‘U’
•A quality measurement of travel
–Drivers and passengers perception of journey
–Rate of motion in distance per unit of time
–Speed or velocity is given by
–Speed u: u=Distance / Time

u= l/t km/hr
–Where
•u is the speed of the vehicle in m/s
•d is the distance traveled in meters
•t time in seconds
2/10/2021 11
Speed Studies
•Various types
–Spot speed
–Running speed
–Journey speed
–Time mean speed
–Space mean speed
2/10/2021 12
2/10/2021 13
14

UNIT-IV
TESTS ON SOILS
Modulus of Subgrade Reaction
The modulus of subgrade reaction (k) is used as a primary input for
rigid pavement design. It estimates the support of the layers below a rigid
pavement surface course (the PCC slab). The k-value can be determined by
field tests or by correlation with other tests. There is no direct laboratory
procedure for determining k-value.
The modulus of subgrade reaction came about because work done
by Westergaard during the 1920s developed the k-value as a spring constant
to model the support beneath the slab
Figure : Modulus of subgrade reaction (k)

The reactive pressure to resist a load is thus proportional to the spring deflection
(which is a representation of slab deflection) and k
Figure : Relation of load, deflection and modulus of subgrade reaction (k).

The value of k is in terms of MPa/m (pounds per square inch
per inch of deflection, or pounds per cubic inch – pci) and ranges from
about 13.5 MPa/m (50 pci) for weak support, to over 270 MPa/m (1000
pci) for strong support. Typically, the modulus of subgrade reaction is
estimated from other strength/stiffness tests, however, in situ values can
be measured using the plate bearing test.
TEST ON AGGREGATES
1. Specific Gravity of Aggregate
2. Shape Tests
3. water absorption
4. Impact Test
5. Abrasion Test
6. Attrition Test
7. Crushing resistance
8. Durability (weathering resistance)
9. Stone polishing value of aggregates
1. Specific Gravity of Fine Aggregate
The aggregate passing through 4.75mm sieve size is called as

fine aggregate. Natural sand is generally used as fine aggregate, silt and
clay are also come under this category. IS specifications classify the fine
aggregate into four types according to its grading as fine aggregate of
grading Zone-1 to grading Zone-4.
The four grading zones become progressively finer from grading
Zone-1 to grading Zone-4. 90% to 100% of the fine aggregate passes 4.75
mm IS sieve and 0 to 15% passes 150 micron IS sieve depending upon its
grading zone.
The purpose of using fine aggregate in concrete is to fill the
voids in the coarse aggregate and to act as a workability agent.
The fine aggregate specific gravity test is used to calculate the specific
gravity of a sample by determining the ratio of the weight of a given
volume of aggregate to the weight of an equal volume of water.
Aggregate specific gravity is used in a number of applications
including in mix design, deleterious particle identification and separation,
and material property change identification etc. Generally the material's
weight is typically measured and then converted to a volume based on its
specific gravity. Correct and accurate material specific gravity
determinations are vital to proper mix design.
An incorrect specific gravity value will result in incorrectly
calculated volumes and ultimately result in an incorrect mix design. Specific
gravity can also indicate possible material contamination, large amount of
deleterious material in an aggregate sample may result in an abnormally low
specific gravity.
Specific gravity differences can be used to indicate a possible
material change. A change in aggregate mineral or physical properties can
result in a change in specific gravity.
Where,
W1= weight of the empty flask
W2= weight of the flask + 1/3rd of fine aggregate
W3=weight of the flask+1/3rd aggregate+ water
W4= weight of the flask+ water
Relevant IS Standard: IS : 2386 (PartIII)-1963: Methods of Test for Aggregates for

Concrete.
Specific Gravity of Coarse Aggregate
Test on Aggregate
Introduction
to
Impact test
44
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Uses of the test
To determine the impact value of the aggregates
used in pavement construction(Road);
To assess their suitability in road layers (base

course, surface course ) construction on the basis of
impact value.
45
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Apparatus used in Impact test
The apparatus of the aggregate impact value test consists of:
A testing machine weighing 45 to 60 kg and having a metal base with a
plane lower surface of not less than 30 cm in diameter. Level and plane
concrete floor of minimum 45 cm thickness are used to support it. The base of
the machine should also have provisions for fixing its base.
A cylindrical steel cup of internal diameter 102 mm, depth 50 mm and
minimum thickness 6.3 mm.
A metal hammer or tup weighting 13.5 to 14.0 kg the lower end is
cylindrical in shape, is 50 mm long, 100.0 mm in diameter, with a 2 mm
chamfer at the lower edge and case hardened. The hammer is arranged in such
a way that it should slide freely between vertical guides and be concentric
with the cup. It is arranged that the free fall of the hammer should be within
380±5 mm.
A cylindrical metal measure having an internal diameter of 75 mm and
depth 50 mm for measuring aggregates.
One end rounded tamping rod 10 mm in diameter and 230 mm long.
A balance of capacity not less than 500 g, and readable and accurate up to
0.1 g.
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Aggregate Impact value test setup
47
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48
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AIM:
To determine the aggregate impact value of coarse
aggregates as per IS: 2386 (Part IV) – 1963.
APPARATUS:
Aggregate Impact Value Tester IS : 2386 (Part-IV)
i) Impact testing machine conforming to IS: 2386 (Part IV) – 1963
ii) IS Sieves of sizes – 12.5mm, 10mm and 2.36mm
iii) A cylindrical metal measure of 75mm dia. and 50mm depth
iv) A tamping rod of 10mm circular cross section and 230mm
length, rounded at one end
v) Oven
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SIEVES OF FINE AGGREGATES
50
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SIEVES OF COURSE AGGREGATES
51
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PREPARATION OF SAMPLE:
i) The test sample should conform to the following grading:
– Passing through 12.5mm IS Sieve 100%
– Retention on 10mm IS Sieve 100%
ii) The sample should be oven-dried for 4hrs. at a temperature of
100 to 110 degree C and cooled.
iii) The measure should be about one-third full with the prepared
aggregates and tamped with 25 strokes of the tamping rod. A
further similar quantity of aggregates should be added and a
further tamping of 25 strokes given. The measure should finally be
filled to overflow, tamped 25 times and the surplus aggregates
struck off, using a tamping rod as a straight edge. The net weight
of the aggregates in the measure should be determined to the
nearest gram (Weight ‘A’).
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Procedure of Aggregate Impact value test
The test sample: normally aggregates sized 10.0 mm to 12.5 mm.
the aggregates should be dried by heating at 100-110 0C for a
period of 4 hours and cooled.
1. Sieve the material through 12.5mm and 10.0 mm IS sieves. The
aggregates passing through 12.5 mm sieve comprises the test
material.
2. Then, just 1/3 rd depth of measuring cylinder is filled by
aggregate by pouring.
3. Compact the material by giving 25 gentle blows with the
rounded end of the tamping rod in the cylinder.
4. Two more layers are added in a similar manner, to make
cylinder full.
5. Strike off the surplus aggregates.
6. Determine the net weight of the aggregates to the nearest gram
(W1).
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7. Bring the impact machine to rest without wedging or packing upon the
level plate, block or floor, so that it is rigid and hammer guide columns are
vertical.
8. 25 gentle strokes with tamping rod are used to compact the test sample by
fixing the cup firmly in position on the base of the machine with placing the
whole of the test sample in it.
9. After that raise the hammer until its lower face is 380 mm above the surface
of the aggregate in the cup and allow it to fall freely on the aggregate sample.
15 such blows at an interval of not less than one second between successive
falls are acted on it.
10. Remove the crushed aggregate from the cup and sieve it through 2.36 mm
IS sieves until no further significant amount passes in one minute. Weight the
fraction passing the sieve to an accuracy of 1 gm (W2). The fraction retained
in the sieve is weighted.
11. Note down the observations in the proforma and compute the aggregate
impact value. The ‘Aggregate Impact Value’ is the mean of two observations,
rounded to a nearest whole number.
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Precautions
1. Place the plunger centrally so that it falls directly on the
aggregate sample and does not touch the wall of the cylinder in
order to ensure that the entire load is transmitted on the
aggregates.
2. In the operation of sieving the aggregates through 2.36 mm
sieve, the sum of weights of fractions retained and passing the
sieve should not differ from the original weight of the specimen
by more than 1 gm.
3. The tamping is to be done properly by gently dropping the
tamping rod and not by hammering action. Also, the tamping
should be uniform over the surface of the aggregate taking care
taking care that the tamping rod does not frequently strike
against the wall of the mold.
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Record of observations
Reading Sample I Sample II
Total weight of dry

357.7
sample taken = W1 gm
Weight of portion
passing 2.36 mm sieve 25.3
= W2 gm
Aggregate impact value

= (W2 / W1 )*100 7.08
percent
Aggregate impact mean

value =
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Interpretation of Results
Aggregate impact value is used to classify the stones in respect of their
toughness property that is shown in table below :
Aggregate Impact value Classification
<10 % Exceptionally strong
10-20% Strong
10-30% Satisfactory for road surfacing
>35% Weak for road surfacing
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The following Aggregate Impact values for different types of road
construction is recommended by IRC.
Maximum aggregate impa

S.N. Types of pavement
ct value
Bituminous surface
dressing penetration
macadam, bituminous
1. 30
carpet concrete and
cement concrete wearing
course.
Bitumen-bound-macadam,
2. 35
base course
WBM base course with

3. 40
bitumen surfacing
Cement Concrete base

4. 45
course
58
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Test on Aggregate
Introduction
to
Los Angeles Abrasion
Test
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Objective
Abrasion test is carried out to test the hardness
property of aggregates. The principle of Los
Angeles abrasion test is to find the percentage wear
due to relative rubbing action between the aggregate
and steel balls used as abrasive charge.
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Apparatus Required
Fig. 1: Balance Balance should be accurate upto 1 g
61
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Fig. 2: Sieves
Sieves required are 80, 63, 50, 40, 25, 20, 12.5, 10,
6.3, 4.75 (as per gradation of aggregate) and 1.7 mm
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Fig. 3: Los Angeles Testing Machine
Inside Length = 50 cm and Inside Diameter = 70 cm
63
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Fig. 4: Abrasive Charges
Diameter = 48 mm and Weight = 390 to 445 g
64
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SIEVES OF FINE AGGREGATES
65
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SIEVES OF COURSE AGGREGATES
66
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3. Reference
Relevant Indian Standard for Los Angeles Abrasion
Test on Aggregate:
IS 2386(Part 4):1963 Methods of Test for Aggregates
for Concrete- Mechanical Properties. Reaffirmed Dec
2016
IS 2386 (Part IV) 1963: Methods of Test for
Aggregates Mechanical Properties, Tenth Reprint
MARCH 1997.
IS 383-1970: Specification for Coarse and Fine
Aggregates.
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4. Procedure
A. Gradation Of Aggregate
1. Gradation of the Aggregate should be carried out so as to assess the Grade of the
Aggregate (A to G)
Table 1: Gradation of Aggregate
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Theory
INTRODUCTION
Aggregates undergo significant wear and tear throughout
their life. Aggregates must be hard and tough enough to resist
crushing, degradation and disintegration and be able to transmit
loads from the pavement surface to the underlying layers and
eventually the subgrade. Testing the strength of parent rock alone
does not exactly indicate the strength of aggregates in concrete.
For this reason assessment of strength of the aggregates are made
by using a sample bulk aggregates in standardized manner. The
principal mechanical property of aggregate required in any
construction is
1. Satisfactory resistance to crushing under the roller
during construction
2. Adequate resistance to surface abrasion under traffic
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Aggregates used in road construction should be strong
enough to resist abrasion and crushing under traffic wheel load. If
aggregates are weak the stability of pavement structure is
adversely affected. If the aggregates used are not resistant to
abrasion it may cause premature failure or a loss of skid
resistance of pavements, also poor resistance to abrasion can
produce excessive dust. Abrasion test is carried out on the
aggregate sample to test the hardness property of aggregates and
to decide whether they are suitable for different pavement
construction works. Los Angeles test is widely used to test
abrasion of aggregate and the method has been standardized in
India (IS:2386 part-IV). The Los Angeles abrasion test finds the
percentage wear due to relative rubbing action between the
aggregate and steel balls.
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Los Angeles machine has a circular rotating drum of
length 520 mm and internal diameter 700 mm mounted on
horizontal axis. An abrasive charge consisting of cast iron
spherical balls of 48 mm diameters and weight 340-445 g is
placed in the cylinder along with the aggregates based on the
selected grading. The number of the abrasive spheres varies
according to the grading of the sample. The quantity of
aggregates to be used depends upon the grading and usually
ranges from 5-10 kg. The cylinder is then locked and rotated at
the speed of 30-33 rpm for a total of 500 -1000 revolutions
depending upon the gradation of aggregates. After specified
revolutions, the material passing 1.7 mm IS sieve is measured
and expressed as percentage total weight of the sample. This
value is called Los Angeles abrasion value.
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The table below shows limits of Los Angeles abrasion value for different
types of road construction:
Max. permissible
Type of Pavement abrasion value in
%
Water bound macadam sub base course 60
WBM base course with bituminous surfacing 50
Bituminous bound macadam 50
WBM surfacing course 40
Bituminous penetration macadam 40
Bituminous surface dressing, cement concrete
35
surface course
Bituminous concrete surface course 30
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Procedure For Los Angeles Abrasion Test
1. The test sample shall consist of clean aggregate which has
been dried in an oven at 105 to 110°C to substantially
constant weight and shall conform to one of the gradings
shown in Table 1. The grading or gradings used shall be
those most nearly representing the aggregate furnished for
the work.
2. The test sample and the abrasive charge shall be placed in
the Los Angeles abrasion testing machine and the machine
rotated at a speed of 20 to 33 rev/min. For gradings A, B, C
and D, the machine shall be rotated for 500 revolutions; for
gradings E, F and G, it shall be rotated for 1000 revolutions
as mentioned in Table 2.
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Table 2: Number of Charges as per Grading of Aggregate
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3. The machine shall be so driven and so counter-
balanced as to maintain a substantially uniform
peripheral speed. If an angle is used as the shelf, the
machine shall be rotated in such a direction that the
charge is caught on outside surface of the angle.
4. At the completion of the test, the material shall be
discharged from the machine and a preliminary
separation of the sample made on a sieve coarser than
the l.70 mm IS Sieve.
5. The material coarser than the 1.70 mm IS Sieve shall
be washed dried in an oven at 105 to 110°C to a
substantially constant weight, and accurately weighed to
the nearest gram (B).
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5. Calculation
1. The difference between the original weight and the final
weight of the test sample is expressed as a percentage of the
original weight of the test sample. This value is reported as
the percentage of wear.
Aggregate Abrassion Value = ((A-B)/A) X 100
where, A = weight in gm of oven-dried sample.
B = weight in gm of fraction retained on 1.70 mm IS Sieves after
washing and oven-dried upto constant weight.
Or
Aggregate Abrassion Value =((W1-W3)/W1) X 100
Where w1= Total weight of aggregate sample, gm
w2 = aggregate sample passing through Is Sieve 1.7mm
W3= aggregate sample retaining through Is Sieve 1.7mm
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Lecture-1
Pavement Design (Unit V)
Mr. M. Gnannendra Babu

Assistant Professor
Department of Civil Engineering
Malla Reddy Institute of Technology and Science (MRITS)
Hyderabad
2/10/2021 1
Introduction Pavement Design
• A highway pavement is a structure consisting of superimposed layers of
processed materials above the natural soil sub-grade, whose primary function
is to distribute the applied vehicle loads to the sub-grade.
• The pavement structure should be able to provide a surface of acceptable
riding quality, adequate skid resistance, favorable light reflecting
characteristics, and low noise pollution.
• The ultimate aim is to ensure that the transmitted stresses due to wheel
load are sufficiently reduced, so that they will not exceed bearing capacity of
the sub-grade.
• Two types of pavements are generally recognized as serving this
purpose, namely flexible pavements and rigid pavements.
• This lecture gives an overview of pavement types, layers, and their
functions, and pavement failures. Improper design of pavements leads to
early failure of pavements affecting the riding quality.
2/10/2021 2
Requirement of Pavement
An ideal pavement should meet the following requirements:
 Sufficient thickness to distribute the wheel load stresses to a safe
value on the sub-grade soil,
 Structurally strong to withstand all types of stresses imposed upon
it,
 Adequate coefficient of friction to prevent skidding of vehicles,
 Smooth surface to provide comfort to road users even at high speed,
 Produce least noise from moving vehicles,
 Dust proof surface so that traffic safety is not impaired by reducing
visibility,
 Impervious surface, so that sub-grade soil is well protected, and
 Long design life with low maintenance cost.
2/10/2021 3
Types of Pavement
Pavement are broadly classified into two category, namely flexible
pavements and rigid pavements.
Flexible Pavement: Wheel loads are transferred by grain-to-grain
contact of the aggregate through the granular structure.
Load transfer in granular structure

2/10/2021 4
Flexible Pavement
• Wheel load acting on the pavement will be distributed to a wider area,
and the stress decreases with the depth.
• Taking advantage of this stress distribution characteristic, flexible
pavements normally has many layers. Hence, the design of flexible
pavement uses the concept of layered system.
• Based on this, flexible pavement may be constructed in a number of
layers and the top layer has to be of best quality to sustain maximum
compressive stress, in addition to wear and tear.
• The lower layers will experience lesser magnitude of stress and low
quality material can be used.
• Flexible pavements are constructed using bituminous materials.
• Flexible pavement layers reflect the deformation of the lower layers on
to the surface layer (e.g., if there is any undulation in sub-grade then it will
be transferred to the surface layer).
2/10/2021 5
Typical Layers of Flexible Pavement
Typical cross section of a flexible pavement
2/10/2021 6
Surface Course: is the layer directly in contact with traffic loads and
generally contains superior quality materials. They are usually
constructed with dense graded asphalt concrete (AC). The functions
and requirements of this layer are:
• It provides characteristics such as friction, smoothness, drainage,
etc. Also it will prevent the entrance of excessive quantities of surface
water into the underlying base, sub-base and sub-grade,
• It must be tough to resist the distortion under traffic and provide a
smooth and skid- resistant riding surface,
• It must be water proof to protect the entire base and sub-grade
from the weakening effect of water.
2/10/2021 7
Binder Course
• This layer provides the bulk of the asphalt concrete structure. Its
chief purpose is to distribute load to the base course.
• The binder course generally consists of aggregates having less
asphalt and doesn’t require quality as high as the surface course, so
replacing a part of the surface course by the binder course results in
more economical design.
Base Course
The base course is the layer of material immediately beneath the
surface of binder course and it provides additional load distribution
and contributes to the sub-surface drainage It may be composed of
crushed stone, crushed slag, and other untreated or stabilized
materials.
2/10/2021 8
Sub-Base Course
• The sub-base course is the layer of material beneath the base course and
the primary functions are to provide structural support, improve drainage,
and reduce the intrusion of fines from the sub-grade in the pavement
structure.
• If the base course is open graded, then the sub-base course with more
fines can serve as a filler between sub-grade and the base course.
• A sub-base course is not always needed or used. For example, a
pavement constructed over a high quality, stiff sub-grade may not need the
additional features offered by a sub-base course. In such situations, sub-base
course may not be provided.
Sub-grade
The top soil or sub-grade is a layer of natural soil prepared to receive the
stresses from the layers above. It is essential that at no time soil sub-grade is
overstressed. It should be compacted to the desirable density, near the
optimum moisture content.
2/10/2021 9
Failure of Flexible Pavements
The major flexible pavement failures are fatigue cracking, rutting, and
thermal cracking.
Fatigue cracking: is due to horizontal tensile strain at the bottom of the

bituminous layer. The failure criterion relates allowable number of load
repetitions to tensile strain.
Rutting: Occurs only on flexible pavements as indicated by permanent

deformation or rut depth along wheel load path. Rutting mainly occurred on
the top of sub-grade due to vertical compressive strain.
Thermal cracking: includes both low-temperature cracking and thermal

fatigue cracking.
2/10/2021 10
Flexible Pavement Design Using IRC
Method
Design Criteria
The flexible pavements has been modeled as a three layer structure
and stresses and strains at critical locations have been computed using
the linear elastic model. To give proper consideration to the aspects of
performance, the following three types of pavement distress resulting
from repeated (cyclic) application of traffic loads are considered:
1. Vertical compressive strain at the top of the sub-grade which can
cause sub-grade deformation resulting in permanent deformation
at the pavement surface.
2. Horizontal tensile strain or stress at the bottom of the bituminous
layer which can cause fracture of the bituminous layer.
3. Pavement deformation within the bituminous layer.
2/10/2021 12
Failure Criteria
Critical location in pavement

A and B are the critical locations for tensile strains (ϵt). Maximum
value of the strain is adopted for design. C is the critical location for
the vertical subgrade strain (ϵz) since the maximum value of the (ϵz)
occurs mostly at C.
2/10/2021 13
Failure Criteria
Fatigue Criteria
• The relation between the fatigue life of the pavement and the
tensile strain in the bottom of the bituminous layer was obtained as:
N f  0.7111004  1/  t   1/ M R 

3.89 0.854
where, Nf indicates fatigue life in number of standard axles, εt is

maximum tensile strain at the bottom of the bituminous layer, and MR
is resilient modulus of the bituminous layer, MPa.
Rutting Criteria
N r  1.411008  1/  v 
4.5337
where, Nr = number of cumulative standard axles, and εv = vertical

strain in the subgrade.
2/10/2021 14
Design Procedure
• Based on the performance of existing designs and using analytical
approach, simple design charts and a catalogue of pavement designs is
prepared by IRC.
• Pavement designs are given for subgrade CBR values ranging
from 2% to 10% and design traffic ranging from 1 msa to 150 msa for
an average annual pavement temperature of 35 0C.
• Using the following simple input parameters, appropriate designs
could be chosen for the given traffic and soil strength:
 Design traffic in terms of cumulative number of standard axles
 CBR value of subgrade.
2/10/2021 15
Design Traffic
• The method considers traffic in terms of the cumulative number of
standard axles (8160 kg) to be carried by the pavement during the
design life. This requires the following information:
• Initial traffic in terms of commercial vehicle per day (CVPD)
• Traffic growth rate during the design life
• Design life in number of years
• Vehicle damage factor (VDF)
• Distribution of commercial traffic over the carriageway.
2/10/2021 16
Design Traffic
Initial Traffic
• Estimate of the initial daily average traffic flow for any road
should normally be based on 7-day 24-hour classified traffic counts
(ADT).
Traffic Growth Rate
• Traffic growth rates can be estimated (i) by studying the past
trends of traffic growth, and (ii) by establishing econometric models.
If adequate data is not available, it is recommended that an average
annual growth rate of 7.5 percent may be adopted.
Design Life
• It is recommended that pavements for arterial roads like NH, SH
should be designed for a life of 15 years, EW and urban roads for 20
years and other categories of roads for 10 to 15 years
2/10/2021 17
Design Traffic
Vehicle Damage Factor
• Vehicle damage factor (VDF) is a multiplier for converting the
number of commercial vehicles of different axle loads and axle
configurations to the number of standard axle-load repetitions.
• It is defined as equivalent number of standard axles per
commercial vehicle.
• The VDF varies with the axle configuration, axle loading, terrain,
type of road, and from region to region.
• The axle load equivalency factors are used to convert different axle
load repetitions into equivalent standard axle load repetitions.
• For these equivalency factors refer IRC:37 2012. The exact VDF
values are arrived after extensive field surveys
2/10/2021 18
Design Traffic
Vehicle Distribution Factor
A realistic assessment of distribution of commercial traffic by direction and by lane is
necessary as it directly affects the total equivalent standard axle load application used in
the design. Until reliable data is available, the following distribution may be assumed.
Single lane roads: Traffic tends to be more channelized on single roads than
two lane roads and to allow for this concentration of wheel load repetitions,
the design should be based on total number of commercial vehicles in both
directions.
Two-lane single carriageway roads: The design should be based on 75 %
of the commercial vehicles in both directions.
Four-lane single carriageway roads: The design should be based on 40 %
of the total number of commercial vehicles in both directions.
Dual carriageway roads: For the design of dual two-lane carriageway roads
should be based on 75 % of the number of commercial vehicles in each
direction. For dual three-lane carriageway and dual four-lane carriageway
the distribution factor will be 60 % and 45 % respectively.
2/10/2021 19
Design Traffic
The design traffic is considered in terms of the cumulative number of
standard axles in the lane carrying maximum traffic during the design
life of the road. This can be computed using the following equation:
365   (1  r) n   1
  
N  A D F
r
where N is the cumulative number of standard axles in terms of million standards axle
(msa), A is the initial traffic in the year of completion of construction in terms of the
number of commercial vehicles per day, D is the lane distribution factors, F is the
vehicle damage factor, n is the design life in years, and r is the annual growth rate of
commercial vehicles.
The traffic in the year of completion is estimated using the following
formula:
where P is the number of commercial vehicles as per
A  P(1  r) x last count, and x is the number of years between the
last count and the year of completion of the project.
2/10/2021 20
Pavement Thickness Design Charts
• For the design of pavements to carry traffic in the range of 2 to
150 msa, use below charts of IRC: 37 2012.
• The design curves relate pavement thickness to the cumulative
number of standard axles to be carried over the design life for different
sub-grade CBR values ranging from 3 % to 15 %.
• The design charts will give the total thickness of the pavement for
the above inputs.
• The total thickness consists of granular sub-base, granular base
and bituminous surfacing. The individual layers are designed based on
the recommendations given below.
2/10/2021 21
2/10/2021 22
2/10/2021 23
Numerical Problem
Design the pavement for construction of a new bypass with the
following data:
1. Two lane carriageway
2. Initial traffic in the year of completion of construction = 400 CVPD (sum of
both directions)
3. Traffic growth rate = 7.5 %
4. Design life = 15 years
5. Vehicle damage factor based on axle load survey = 2.5 standard axle per
commercial vehicle
6. Design CBR of subgrade soil = 4%.
2/10/2021 24
Numerical Problem
Solution: Distribution factor = 0.75
Total pavement thickness for CBR is 4% and traffic 7.2 msa from
IRC:37 2001 chart1 = 660 mm
Pavement composition can be obtained by interpolation from
Pavement Design Catalogue (IRC:37 2001).
Bituminous surfacing = 25 mm SDBC + 70 mm DBM
Road-base = 250 mm WBM
sub-base = 315 mm granular material of CBR not less than 30
2/10/2021 25
Rigid Pavement
• Rigid pavements have sufficient flexural strength to transmit the
wheel load stresses to a wider area below.
• A typical cross section of the rigid pavement is shown in figure.
• Compared to flexible pavement, rigid pavements are placed either
directly on the prepared sub-grade or on a single layer of granular or
stabilized material.
• Since there is only one layer of material between the concrete and
the sub-grade, this layer can be called as base or sub-base course.
2/10/2021
Typical Cross section of rigid pavement 26
Rigid Pavement
• In rigid pavement, load is distributed by the slab action, and the
pavement behaves like an elastic plate resting on a viscous medium
(See Figure).
• Rigid pavements are constructed by Portland cement concrete
(PCC) and should be analyzed by plate theory instead of layer theory
which is a simplified version of layer theory that assumes the concrete
slab as a medium thick plate which is plane before loading and to
remain plane after loading.
• Bending of the slab due to wheel load and temperature variation
and the resulting tensile and flexural stress.
2/10/2021 Elastic plate resting on viscous foundation 27

Environmental and Other Factors
• The environmental factors such as aesthetics, landscaping, air
pollution, noise pollution, and other local condition should be given
the considerations in the design of road geometric
• Some of the arterial high speed highways and expressways are
designed for higher speed standards and uninterrupted flow of
vehicles by providing controlled access and grade separated
intersection.
2/10/2021 28
Factors for design of Rigid Pavement
• Modulus of sub-grade reaction

• Relative stiffness of slab to sub-grade
• Critical load positions
• Equivalent radius of resisting section
Modulus of sub-grade reaction
• Westergaard considered the rigid pavement slab as a thin

elastic plate resting on soil sub-grade, which is assumed as
a dense liquid. The upward reaction is assumed to be
proportional to the deflection.
• Base on this assumption, Westergaard defined a modulus
of sub-grade reaction K in kg/cm3given by
𝑃
K=∆
Where Δ is the displacement level taken as 0.125 cm and p is
the pressure sustained by the rigid plate of 75 cm diameter at
a deflection of 0.125 cm.
Relative stiffness of slab to sub-grade
• Degree of resistance to slab deflection is offered by the

sub-grade. The sub-grade deformation is same as the slab
deflection.
• This pressure deformation characteristics of rigid
pavement lead Westergaard to the define the term radius
of relative stiffness l in cm
𝐸ℎ3
L=( )1/4
12𝑘(1−𝜇 2)
Critical load positions
• There are three typical locations namely the interior, edge

and corner, where differing conditions of slab continuity
exist. These locations are termed as critical load positions.
Equivalent radius of resisting section
• When the interior point is loaded, only a small area of the

pavement is resisting the bending moment of the plate.
Westergaard's gives a relation for equivalent radius of the
resisting section in cm.
where a is the radius of the wheel load distribution in cm and

h is the slab thickness in cm.
Thank you
2/10/2021 34

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MALLA REDDY INSTITUTE OF TECHNOLOGY & SCIENCE

2. Kadiyali L.R. and Lal N B, Principles and Practices of Highway

• Basic mode of transportation are

• Development, planning and location

• Highway design, geometric and structure

• Traffic performance and its control

• Materials, construction and maintenance

• Economic, finance and administration

• At 0.66 km of highway per square kilometer of

Distribution of 100% cess on petrol as follows:

50% cess on diesel for Rural Road development

• It was formed in 1939

• Planning, development and maintenance of

• To ascertain the nature and extent of

Depending the type of Carriage way

Depending upon the pavement surface

Based on Load or Tonnage

Based on location and function ( Nagpur road plan )

• In particular for short distance travel, road transport

The Mumbai-Pune Expressway as seen

• Total length of all SH in the country is 1,37,119 Kms.

• Important roads with in a district serving

• India has a total of 4,70,000 kms of MDR.

• No frontage access, no standing vehicle,

• Bus stops but no standing vehicle.

• Design Speed : 30km/hr.

• A driveway is a type of private road for local access

• Rectangular or Block patterns

• Short- desirable to have a short alignment between two

 Map study (Provisional alignment Identification)

 Final location and detailed surveys

• Finalise the best alignment from all considerations by

Elements of physical access

2/10/2021 DEPARTMENT OF CIVIL ENGINEERING 1

 IRC recommended the longitudinal co-efficient of friction

 In adequate compaction of the fill, subgrade and pavement

SL. Class of road Width of carriageway

2 Two lane without raised kerbs 7.0

3 Two lane with raised kerbs 7.5

4 Intermediate lane 5.5

5 Multilane pavement 3.5/lane

Plane and rolling Mountainous and

4 Village roads-single lane 7.5 4

• It is provided at the edge of the shoulder

• SSD is the minimum sight distance available on a highway at any

SSD=lag distance + braking distance

Coefficient of longitudinal friction

• Two-way traffic single lane road: SSD=2*SSD

OSD = 0.28 Vb. t +0.28Vb .T + 2s + 0.28 V.T

S = SPACING OF VEHICLES = (0.2 V b+ 6)

If the speed of the overtaken vehicle is not given

The minimum overtaking sight distance = d1+d2+d3 for two-way traffic.

• From drainage consideration it is necessary to have a

Split-up into two parts::

2nd Method: Crown shifted outwards

Rotation of pavement to attain full superelevation

From Δ OAB, OA2 = OB2 –