Ce2026 traffic engineering and management notes

TRAFFIC ENGINEERING
AND MANAGEMENT
www.Annauniversityplus.com
special PPT'S
included last.

SYLLABUS
1. INTRODUCTION
Significance and scope, Characteristics of Vehicles and Road
Users, Skid Resistance and Braking Efficiency (Problems),
Components of Traffic Engineering- Road, Traffic and Land Use
Characteristics
2. TRAFFIC SURVEYS AND ANALYSIS
Surveys and Analysis - Volume, Capacity, Speed and Delays,
Origin and Destination, Parking, Pedestrian Studies, Accident
Studies and Safety Level of Services- Problems
3. TRAFFIC CONTROL
Traffic Signs, Road Markings, Design of Traffic Signals and
Signal Co-ordination (Problems), Traffic control Aids and Street
Furniture, Computer Applications in Signal Design

4. DESIGN OF GEOMETRIC INTERSECTIONS
Conflicts at Intersections, Classification of Intersections at
Grade, Grade Separators(Concepts only), Principles of
Intersection Design, Elements of Intersection
Design,Channelisation and Rotary Design (Problem)
5. TRAFFIC MANAGEMENT
Traffic Management- Traffic System Management (TSM)
and Travel Demand Management (TDM), Restrictions on
Turning Movements, One-way Streets, Traffic Segregation,
Traffic Calming, Tidal Flow Operations, Exclusive Bus Lanes–
Introduction to Intelligence Transport System (ITS)

Text Books
1. Khanna K and Justo C E G, Highway
Engineering, Khanna Publishers
2. Kadiyali L R, Traffic Engineering and Transport
Planning, Khanna Technical Publications
References
1. Indian Roads Congress (IRC) specifications:
Guidelines and special publications on Traffic
Planning and Management
2. Guidelines of Ministry of Road Transport and
Highways, Government of India.
3. Subhasg C.Saxena, A Course in Traffic Planning
and Design, Dhanpat Rai Publications

Chapter 1. Introduction
Definition, scope and goal
Objects of traffic engineering
Background of traffic engineering development
Some basic concepts in traffic engineering
Main elements in traffic engineering
Characteristics
Challenges traffic engineers face
References

– Transportation Engineering is defined as a discipline
applying technology and scientific principles to the planning,
functional design, operation, and management of facilities
for all modes of transportation
– Transportation mode includes: land, rail, water, air and pipe
– The focus of this course is on surface (land) transportation
and connection with other modes

Scope of Traffic Engineering
Surface transportation
Relationships and connection with other modes
of transportation
Major modes of surface transportation
Automobile,
Bus,
Truck and
Bike

Goal of Traffic Engineering
Explore how to provide for the safe, rapid,
comfortable, convenient, economical, and
environmentally compatible movement of people
and goods.
Safe --- public safety
Rapid --- time value and customer service
Comfortable/convenient --- Level of service
Economical --- Social cost
Environmental --- Clean air and sustainability
Movement --- Mobility

Unit I-INTRODUCTION
• Traffic engineering is a branch of civil
engineering that uses engineering techniques
to achieve the safe and efficient movement of
people and goods on roadways
• It focuses mainly on research and construction
of the infrastructure necessary for safe and
efficient traffic flow, such as road geometry,
sidewalks and crosswalks, segregated cycle
facilities, shared lane marking, traffic signs,
road surface markings and traffic lights.

It is the phase of transportation engineering
that deals with the planning, geometric design
and traffic operations of roads, streets and
highways, their networks, terminals, abutting
lands, and relationships with other modes of
transportation

Basic Components in Traffic Engineering
1. Road users including
Drivers,
Cyclists and
Pedestrians
2. Vehicles
3. Roads and highways
4. Control devices

Five critical components interact in a traffic system:
1. Road users-drivers, pedestrians, bicyclists,
and passengers
2. Vehicles-private and commercial
3. Roads and highways
4. Traffic control devices
5. The general environment

Traffic Control
Traffic controls could be easily designed if all
drivers reacted to them in exactly the same way.
Safety could be more easily achieved if all vehicles
had uniform dimensions, weights, and operating
characteristics.
Drivers and other road users have widely
varying characteristics.
Simple subjects like reaction time, vision
characteristics, and speed become complex
because no two road users are the same.

Traffic engineers provide information
to drivers in uniform ways. Although this does
not assure uniform reactions from drivers, it
at least narrows the range of behavior as
drivers become accustomed to and familiar
with the cues traffic engineers design into the
system.

Road User Characteristic
 Visual
 Fields of Vision
Acute or clear vision cone
Fairly clear vision cone
Peripheral vision
 Perception-reaction time (PRT)
Detection
Identification
Decision.
Response
 Reaction Time
 Reaction Distance
 Expectancy
Continuity.
Event.
Temporal.
 Age
 Complexity of reaction
 Presence of alcohol and/or drugs in the driver's system

Road User Characteristic
Visual
The test is a standard chart-reading
exercise that measures static visual acuity -that
is, the ability to see small stationary details
clearly.

Fields of Vision
Acute or clear vision cone-3° to 10° around the line
of sight; legend can be read only within this narrow field
of vision.
Fairly clear vision cone-10° to 12° around the line of
sight; color and shape can be identified in this field.
Peripheral vision -This field may extend up to 90° to
the right and left of the centerline of the pupil, and up to
60° above and 70° below the line of sight. Stationary
objects are generally not seen in the peripheral vision
field, but the movement of objects through this field is
detected.

Perception-reaction time (PRT)
The perception time includes the
detection, identification, and decision elements
involved responding to a action, whereas the
reaction time is the time it takes to initiate the
physical response.
Some references refer it to the
Perception Identification Emotion Volition time
or PIEV, which is comparable in concept to the
PRT.

Perception- Reaction Time
The time of critical driver characteristic is
perception-reaction time (PRT). During perception and
reaction, the driver must perform four distinct processes :
• Detection. In this phase, an object or condition of concern
enters the driver's field of vision , and the road users driver
becomes consciously aware that something requiring a
response is present.
• Identification. In this phase, the driver acquires sufficient
information concerning the object or condition to allow the
consideration of an appropriate response.
• Decision. Once identification of the object or condition is
sufficiently completed, the driver must analyze the
information and make a decision about how to respond.
• Response. After a decision has been reached, the response is
now physically implemented by the driver.

Reaction Time
For signal timing purposes, the Institute of
Transportation Engineers recommends a PRT
time of 1.0 seconds
The American Association of State Highway
and Transportation Officials (AASHTO)
mandates the use of 2.5 seconds for most
computations involving braking reactions

Reaction Distance
Reaction time is the distance the vehicle travels
while the driver goes through the process.
In the example of a simple braking reaction, the
PRT begins when the driver first becomes aware of an event
or object in his or her field of vision and ends when his or her
foot is applied to the brake.
During this time, the vehicle continues along its
original course at its initial speed. Only after the foot is
applied to the brake pedal the vehicle begin to slow down in
response to the stimulus .
The reaction distance is simply the PRT
multiplied by the initial speed of the vehicle.

Expectancy
• Continuity. Experiences of the immediate past are
generally expected to continue. Drivers do not, for
example, expect the vehicle they are following to
suddenly slow down.
• Event. Things that have not happened previously will
not happen. If no vehicles have been observed entering
the roadway from a small driveway over a reasonable
period of time, then the driver will assume that
none will enter now.
• Temporal. When events are cyclic, such as a traffic
signal, the longer a given state is observed, drivers
will assume that it is more likely a change will occur.

Other Factors Affecting PRT
 Age,
 Fatigue,
 Complexity of reaction, and
 Presence of alcohol and/or drugs in the driver's
system

VEHICLE CHARACTERISTICS
Size
Weight
Axle configuration
Power to weight ratio
Turning ratio
Turning path
Pollution created
Design vehicle

Size ,Weight ,Axle Configuration
A vehicle has three dimension : length , width,
height
The height of vehicles are more important
considered in placing of signals and designing over
passes and under passes.
Weight of the vehicle plays an important
role in design of both flexible and rigid pavement.
The weight of vehicle is transferred through axle ,it
is important to design a pavement.

Power to Weight ratio of vehicle
 Human powered vehicles – cycles ,rickshaw have
low powered to weight ratio and their acceleration
characteristic , speed on slopes are low.
 Motorized vehicle - have high power to weight ratio
 Heavy vehicles- have poor power to weight ratio.
Power to Weight ratio is important factors
as it relates to operating efficiency of vehicles.

Turning radius and turning path

MINIMUM TURNING RADIUS
Minimum turning radius is the radius
of the circle that will be traced by the front
wheel if the vehicle moved with its steering
maximum extend
Big vehicle have bigger turning radius and
small vehicle have smaller radius.

Turning path
Since wheel turns the rear wheel
are fixed and the vehicle body extend beyond the
tyres, the effective width of vehicle on a turn is
increases
The width of the road on curves is
increased in order to accommodate the increase
effective width of vehicle

Vehicle Pollution
 Release hydrocarbons.
 Hydrocarbons react with nitrogen oxide in the
presence of sunlight to produce ozone
 It releases major components of nitrogen
which is the main causes of acid rain
 Carbon monoxide reduces the flow of blood
streams
 Green house gases also emitted-carbon dioxide
 Noise pollution-age of vehicle, tyre type etc.
 Physiological problems-sleep ,concentration

DESIGN VEHICLE
TYPES OF VEHICLES:
 Motorized two wheeler
 Motorized three wheeler
 Passenger cars
 Buses
 Trucks
 Slow non motorized vehicle like cycles
Engineer needs to choose a type of vehicle based on the
characteristic of vehicle the road must be designed
IRC –Indian Road Congress
AASHTO- The American Association of State Highway
and Transportation Officials (AASHTO)
gives the design of roads

Vehicle characteristic
• Design vehicle
Selection of design vehicle can have a good effect
on use of roadway facilities such as turning radius,
turning pocket length, U-turn from left-turn-bay, and
design of parking .
• Acceleration performance of vehicle
Determination of length of acceleration lane when
merging, dual objectives of greater power and
improved fuel efficiency

Power performance of vehicle
Resistance to motion of a vehicle
The power developed by the engine should be
sufficient to over come all resistance to motion at
desired speed and to accelerate an any desired rate to
the desired speed
Rolling resistance
Air resistance
Grade resistance
Inertia force during acceleration and de
acceleration
Transmission losses
Tractive resistance
Pp= Pf+ Pa+Pi+Pjwww.Annauniversityplus.com

Forces acting on a moving vehicle

ROLLING RESISTANCE
When the vehicle wheels rolls over the
road surface ,the irregularities and roughness
of the surface causes deformation of the tyres,
and some times the road surface may go
deformation
Rolling resistance Pf = m x f x g
m = mass of the vehicle in kg
f = coefficient of rolling resistance
Pf = rolling resistance in N
G = acceleration due to gravity in m /sec2

VALUES OF ROLLING RESISTANCE
Types of surfacing Co efficient of
rolling resistance
CEMENT CONCRETE AND ASPHALT
SURFACING
0.01 to 0.02
ROAD WITH SMOOTH CHIPPING ,
GRAVEL SURFACE TREATED WITH
BITUMINOUS BINDER
0.02 to 0.0025
ROAD WITH SMOOTH CHIPPING ,
GRAVEL SURFACE NOT TREATED WITH
BITUMINOUS BINDER
0.03 to 0.04
COBBLESTONE PAVEMENT 0.04 to 0.05
EARTH ROADS, SMOOTH AND COMPACT 0.03 to 0.06
PLOUGHED FIELD ,SWAMPY GROUND 0.15 to 0.30

VALUES OF ROLLING RESISTANCE INDIAN STANDARD
TYPES OF SURFACING CO EFFICIENT OF ROLLING
RESISTANCE
ASPHATIC CONCRETE 0.01
PREMIXED CARPET IN GOOD
CONDITION
0.016
PREMIXED CARPET IN BAD CONDITION 0.022
WATER BOUND MACADAM IN GOOD
CONDITION
0.025
WATER BOUND MACADAM IN
BADCONDITION
0.037
GRAVEL 0.046
EARTH 0.055

Rolling resistance depend on speed also
fv = fo [ 1 + 0.01 (V-50)]
fv = coefficient of rolling resistance at speed V
V = speed in K.P.H
fo = coefficient of rolling resistance

AIR RESISTANCE
 Resistance caused against side of vehicles body
 Wheel causes power loss
 It exert reaction pressure against the front of the
vehicle
Pa = Ca x A x V2
Pa = air resistance in N
A= projected front area
V= velocity of speed in m/sec
Ca = coefficient of air resistance
G = acceleration due to gravity 9.81 m/sec2

COEFFICIENT OF AIR RESISTANCE
TYPE OF VECHICLE FRONTAL
AREA m2
MASS in kg COEFFICIENT
CAR 1.63 1065 0.42
AMBASSADOR CAR 2.15 1365 0.39
JEEP 2.38 1200 0.37
TATA TRUCK 5.37 6120 0.48
ASHOK LEYLAND 5.37 8125 0.48
MARUTI CAR 1.54 880 0.40

GRADE RESISTANCE
When a vehicle which has to moving on a
level stretch at a particular speed has to move
up in incline, addition work has to be done.
Pi= (m x i x g) /100 (+ or -)
Pi = grade resistance

INERTIA FORCE DURING ACCELERATION
AND REACCELERATION
Inertia force
Force = mass x acceleration
Pj = m x a = m x (dv/dt)
m = mass of vehicle in kg
Pj = Inertia force
TRANSMISSION LOSSES
 Losses in power from the engine to gear system. The vehicle
has a system of gear to alter the speed.
 At starting of vehicle high power is needed and speed is low.
 For high power engine for climbing a hill the speed is
reduced

POWER REQUIRES OF A VEHICLE
The mechanical power developed by
the engine is transmitted to the driving wheels
by transmission system.
Rear axle torque Ta = k x Tc x Gt x Ga
Tc = engine torque
Gt = transmission gear ratio
Ga =rear axle gear ratio = 0.80 to 0.90
K = efficiency of transmission system

Pp = (rear axle torque/radius of rolling tyre)
Pp = tractive force
Pp = (K x Te x Gt x Ge) / rw
Power output = Pp x v
v= speed in m/sec
v = (V x 1000)/3600=V/3.6
Power output
= (Pp x V)/3.6
Power output
= (Pv x 0.377 x rw x n)/(Gt x Ga)
Engine power in watts
= (Pv x 0.377 x rw x n)/(Gt x Ga x k)

Tractive resistance
Pp= Pf+ Pa+Pi+Pj
Pa = Air resistance in N
Pf = Rolling resistance in N
Pi = grade resistance
Pj=inertia force due to acceleration and de
acceleration.

Problem
• A passenger car weighing 2 tones is requires to
accelerate at a rate of 3 /sec 2 in the first gear
from a speed of 10 K.P.H the gradient is + 1
percentage and the road has a black topped
surface. The frontal projection area of the car is
2.0 m2.the car tyres have a radius of 0.33 m.
The real axle gear ratio is 3.82 :1 and the first
gear ratio is 2.78 :1 .Calculate the engine
horsepower needed and the speed of engine.
Make suitable assumption

SOLUTION:
Tractive resistance
Pp= Pf+ Pa+Pi+Pj
Pf = m x f x g
f= 0.02 assume
Pf = 2000 x 9.81 x 0.02
= 392.4 N
Pa = Ca x A x v2
Ca = 0.39
A= 2.15 m2
V=10 KMPH
Pa = 0.39 x 2.15 x (15/3.6) x (15/3.6)
= 14.5 N

Pi = (m x i x g) /100
= 2000 x 9.81 x (1/100)
= 196.3 N
Pj= m x a
= 2000 x 3
= 6000N
Pp= Pf+ Pa+Pi+Pj
= 392.4 +14.5+196.2+6000
= 6603.1 N

Power output = Pp x v
= Pp x (V/3.6)
= 6603.1 x 10/3.6
= 183441.9 W
= 183441.9/735 = 24.95 hp
Assume transmission efficiency of 0.90
The engine horse power V
= 24.95/0.90 = 27.72 hp
V= 0.377 x rw x n/Gt x Ga
rw = ro x λ
λ= tyre deformation factor = 0.935
= 0.935 x 0.33
= 0.308 m
N = (10 x 2.78 x 3.82)/(0.377 x 0.308)
= 915 R.P.M

Braking system
Braking system is more important for safety
The safe stopping distance is the distance
travelled during the perception and reaction time
and the distance required to stop the vehicle after the
brakes are applied.
The braking distance
d = V2/254f
V= speed in K.P.H
f = coefficient of friction between the tyres and the
pavement

The braking character of the vehicle influence
the skidding of the vehicle
Acceleration rate is governed by vehicle
transmission system, weight and horse power
Acceleration rate
Medium passenger car = 3-8 K.P.H per sec
Trucks and busses = 1-4 K.P.H per sec

Deceleration rates
The maximum deceleration is related to the coefficient of
friction between the tyres and the pavement
Force required to decelerate=
F= m x d
F= force required to decelerate in N
M = mass of vehicle in kg
d = deceleration in m /sec 2
d = F/m
But
f = F/(m x g)
f = coefficient of friction
d = f x g
d =9.81 f

Deceleration rate
Deceleration in
m/s2
f
Comfortable to passenger 2.62 0.27
Undesirable but not alarming to
passenger
3.39 0.34
Severe and uncomfortable to passenger 4.26 0.43

When the vehicle is travelling at a
particular speed is suddenly allowed to move by
switch off the engine and putting the gear neutral
and deceleration in caused
Pp = Pf +Pa +or -Pi+or -Pj
Pp=0 and i=0
Pj=Pa+Pf
m(dv/dt)=Cv x A x v2 + (mxf xg)
(dv/dt)= (Cv x A x v2)/m + (f xg)

Problem
A ambassador car travelling at a speed of 60 K.M.H
on a WBM road in good condition is suddenly allowed to
coast by switching off the engine and putting the gear in
neutral. What is the deceleration caused.
Solution:
(dv/dt) = (Cv x A x v2)/m + (f xg)
Cv =0.39 kg/m2
A =2.15 m2
M =1365 kg
For WBM f= 0.025
(dv/dt)=(0.39 x 2.15)/1365 x (60/3.6) x (60/3.6) + 0.025 X 9.81
=0.42 m sec2

Skidding
Road accident are very commonly caused in
pavement which results due to skidding of
vehicle.
When a driver moving at speed applies the
vehicle brakes suddenly, stability of vehicle is the
friction that develops in the tyre pavement
interference.

If the friction that can be mobilized is greater
than the deceleration force , the vehicle comes to
safe halt.
If the pavement is wet the friction developed
is much smaller than the deceleration force.
In USA the skid resistance is denoted by skid
number which is 100 times the friction factor
µ=α/g
α = acceleration or deceleration of the vehicle
g= acceleration of gravity.

Factors affecting skid resistance
Pavement
Effect of water on the surface
Speed
Tyre characteristics

Skid Resistance Value
Skid Resistance Value, SRV
This is the value obtained from the actual road
surface, measured using the Portable Skid
Resistance Tester.
The resistance to skidding of a road surface,
i.e. SRV, is dependent on the PSV (polished stone
value) of the aggregate in the wearing course
material and the texture (roughness) of the surface
of the wearing course material.

Skid Number Comments
<30 Take measures to correct
≥30 Acceptable for low volume roads
31 - 34 Monitor pavement frequently
≥35 Acceptable for heavily traveled roads

Measurement of skid resistance
Polished Stone Value, PSV
This is a value of an individual aggregate,
found by subjecting the aggregate to a standard
polishing process and then testing the aggregate
with the Portable Skid Resistance Tester.
The testing procedure and description of the
process is set out in,B.S. 812:Part 114.

METHODS OF MEASUREMENT
SKID RESISTANCE
–Stopping of test vehicle
–Braking of trailers towel by vehicle
–Braking of vehicle with test wheel
–Measuring side way force that develops
when placed at an inclination side slips
–Portable laboratory test

• Stopping of test vehicle
f= v2 /2gd
v in m/sec
d distance travelled after braking
f friction factor
• Braking of trailers towel by vehicle
SN=100 x f =100 x (F/W)
F=force at tyre pavement interface
W=load normal to the tyre

• Measuring side way force that develops when
placed at an inclination side slips
– a test wheel that is set at 20°
– 2750 lit capacity
– 200 kg dead weight load
SFC= sideways force/vertical reaction between tyres and road

PROBLEM
• A test car of mass 1250 kg is travelling AT a
speed of 72 kmph when it is suddenly bracked
by locking the wheel.the vehicle comes to stop
in a distance of 50 M.Calculate the friction
factor.(ANS=0.41)
• A trailer wheel ,loaded to 300 kg is locked by
braking. The horizontal force at a tyre road
interface then developed 1200 N. Calculate
skid number.(ANS =41)

TRAFFIC SURVEYS

TRAFFIC SURVEYS
Traffic Surveys – Volume, Speed and
Delays, Origin and Destination, Parking,
Accident-design of questionnaires for socio
economic surveys- Analysis- Capacity of road
-Level of Services -Interpretation of traffic
studies- Conclusion

TRAFFIC STUDY:
Traffic Study is carried out for:
To obtain the knowledge of the type and volume
of traffic at present and to estimate future traffic that
the road is expected to carry.
To determine the facilities provided on the roads
such as traffic regulation and control, intersections, so
that improvement on the basis of traffic density may
be carried out

To design the geometric features and pavement
thickness on the basis of traffic surveys.
To design bridges & culverts.
Survey related to accidents helps in redesigning of
roads, increasing road width and to maintain regulation
and controls

TYPES OF SPEEDS USED IN TRAFFIC
ANALYSIS
• TIME MEAN SPEED
• SPACE MEAN SPEED
• RUNNING SPEED
• JOURNEY SPEED
• PERCENTILE SPEEDS

Speed
Speed is one of the most important
characteristic of traffic and is measured frequently.
It is expressed in metric unit in kilometers per
hour.
Running Speed is the average speed maintained
by a vehicle over a given course while the vehicle is
moving.
Running speed = Length of course /running time
=length of course /(journey time – delay)

JOURNEY TIME
It is the effective speed of the vehicle between two
points
Journey time =distance /total time(including delay)
Time mean speed is the average speed measurement
at one point in space over a period of time.
Space mean speed is the average speed measurement
at an instant of time over a space

• Time mean speed is defined as the average speed
of all the vehicles passing a point on a highway
over some specified time period.
• Time mean speed is a point measurement
• Space mean speed is defined as the average speed
of all the vehicles occupying a given section of a
highway over some specified time period.
• Space mean speed is a measure relating to length
of highway or lane

Vehicle Time, Sec Speed, m/sec
A 10 10
B 20 5
C 25 4
Total 55 19
Distance Over Which Observations are made = 100 m
• Time Mean Speed = 19/3 = 6.33 m/sec
• Space Mean Speed = 300/55 = 5.45 m/sec

Uses of spot speed
• For geometric design of roads, design speed
can be selected and the horizontal curvature,
vertical profile, sight distance and super
elevation can be estimated.
• For regulation and control of traffic operation,
size of signals
• For analysis of causes of accident
• Studies of improvement of roads
• Problems of congestion

Uses of Journey speed and delay
• Cost of journey
• Congestion, capacity and level of service
• Transportation planning
• Studies of improvement of roads
• Design and installation of traffic control
devices

Methods of measurement of spot
speed
• Observation of time taken by a vehicle to
cover by a known distance
– Timed over a long distance
• Direct timing
• Enoscope
• Pressure contact tubes
– Timed over a short distance
• Radar speedometer
• Photographic method

Recommended Base Length
Average speed Base length in metres
Less than 40 27
40 to 65 54
Greater than 65 81

Traffic flow
• Counting the number of vehicles on a road
–Flow
–Volume
• Flow is defined as the number of vehicles that pass a
point on a highway or a given lane or direction of a
highway during a specific time interval.
• The measurement is carried out by counting the
number of vehicles nt, passing a particular point in
one lane in a defined period t.
• Then the flow q expressed in vehicles/hour is given
by
q = nt/twww.Annauniversityplus.com

Traffic Volume
• The variation of volume with time, i.e. month
to month, day to day, hour to hour and within a
hour is also as important as volume calculation.
• Volume variations can also be observed from
season to season. Volume will be above
average in a pleasant motoring month of
summer.
• It will be more pronounced in rural than in
urban area.

Different traffic studies:
 Traffic Volume study
 Speed Studies
 Spot speed study
 Speed and delay study
 Origin and destination study (O & D)

Classified volume count
• It is the most common highway design
• Volume or flow is expresses in vehicles per hour
or vehicles per day.
• In India the survey is to convert the mixed traffic
into passenger car unit.
• Peak hour traffic is needed for the design of
intersections, whereas for determine the number
of lanes in the carriage way the daily traffic is
needed. www.Annauniversityplus.com

• The traffic counts are taken by noting the number of
vehicles of various classes that passes the count point in
each direction during periodic time intervals.
• Traffic census is taken regularly on NH network twice a
year, for seven consecutive days in each round
• One round covers peak season and other the lean season.
• The average of seven days traffic is average daily traffic.
• If the traffic is taken continuously for all the days in a year
the average traffic is known as AADT annual average daily
traffic.

Classified volume count

Types of volume measurements
• Average Annual Daily Traffic(AADT) :
– The average 24-hour traffic volume at a given
location over a full 365-day year, i.e. the total number
of vehicles passing the site in a year divided by 365.
• Average Annual Weekday Traffic(AAWT) :
– The average 24-hour traffic volume occurring on
weekdays over a full year. It is computed by dividing
the total weekday traffic volume for the year by 260.

Types of volume measurements
• Average Daily Traffic(ADT) :
– An average 24-hour traffic volume at a given
location for some period of time less than a year.
It may be measured for six months, a season, a
month, a week, or as little as two days. An ADT is a
valid number only for the period over which it was
measured.
• Average Weekday Traffic(AWT) :
– An average 24-hour traffic volume occurring on
weekdays for some period of time less than one
year, such as for a month or a season.

Traffic Volume study:
Traffic Volume is the number of vehicles crossing a
section of road per unit time at any selected period.
The commonly used units are vehicles per day and
vehicles per hour.
The various methods available are
1) Manual methods.
2) Combination of manual and mechanical
methods.
3) Automatic devices.
4) Moving observer method.
5) Photographic methods

Manual counts
This method employs a field team to record
traffic volume on the prescribed record sheets.
In this method first the fluctuations of traffic
volume during the hours of the day and the daily
variations are observed.

ADVANTAGE
Gives classification of vehicles and turning
moments
DISADVANTAGE
It cannot work throughout day and night

Combination of Manual and Mechanical
methods
It is the multiple pen recorders.
A chart moves continuously at the speed of a
clock. Different pens record the occurrence of
different events on the chart.
A particular switch may be pressed whenever
a particular class of vehicles arrives and this
operates the pen on the channel which can be
identified with the arrival of a particular class of
vehicle

ADVANTAGE
The classification and vehicle count are
performed simultaneously.
DISADVANTAGE
It does not give turning moment of vehicle.

Speed studies
Spot speed:
Spot speed is the instantaneous speed of a
vehicle at a specified section or location.
Methods of measuring Spot Speeds:
1. Long base methods
2. Short base methods

Spot speed by Endoscope
It is one of the simplest methods of
finding spot speed.
Its principle is the observer is stationed on
one side of the road and starts a stop watch when a
vehicle crosses that section (i.e., observer) .
The enoscope is placed at a convenient
distance say30m to 50m, the moment when the
vehicle crosses the section where endoscope is
fixed, the stopwatch is stopped.
Time required to cross the known length is
found and is converted to speed in KMPH

cumulative speed distribution
• 85th percentile speed:
• It is the speed at or below 85
percentage of the vehicle are
passing the point on the
highway.
• Only 15 % of the vehicle exceed
the speed at that spot.
• The driver exceeding 85 th
percentile speed are usually
consider to drive faster than the
safe speed under existing
condition hence speed is
adopted as safe speed limit.
• 98 th percentile speed is taken
for highway geometric design.

Origin and Destination Studies:
The O & D studies of vehicular traffic determines
their number, their origin and destination in each
zone under study. The various applications of O & D
studies may be summed up as follows:
– It is carried out for assessing the by passable
traffic at towns and for planning new facilities like
expressways.
– It is done by many methods by registration
number matching. Road side interview and post
card questionnaires.

Origin and destination survey
₋ To locate expressway or major routes along the
desire lines.
₋ To judge the adequacy of parking facilities and
to plan for future.
₋ To locate intermediate stops of public
transport.
₋ To establish preferential routes for various
categories of vehicle including by pass

INFORMATION TO BE COLLECTED IN O-D
SURVEYS
• Origin
• Destination
• Purpose of Trip
• Frequency
• Travel Time
• Travel Cost
• Route Preferredwww.Annauniversityplus.com

Methods for collecting the O & D data
Road-side interview method,
License plate method.
Return post card method,
 Tag-on-car method and
The choice of the method is made
judiciously depending on the objective and
location

Road-side interview method:
The vehicles are stopped at previously
decided interview stations, by a group of
persons and the answers to prescribed
questionnaire are collected on the spot.
The information collected include the place
and time of origin and destination, route,
locations of stoppages, the purpose of the trip,
type of vehicle and number of passengers in
each vehicle noted .

License plate method:
The entire area under study is cordoned
out and the observers are simultaneously
stationed at all points of entry and exit on all
the routes leading to and out of the area.
Each party at the observation station is
given synchronized time pieces and they note
the license plate numbers(registration
numbers) of the vehicle entering and leaving
the cordoned area and the time.

Presentation of O and D Data:
The data are presented in the following forms
(i) Origin and destination tables are prepared
showing number of trips between different
zones.
(ii) Desire lines are plotted which a graphical
representation is prepared in almost all O & D
surveys.

Desire lines
• Desire lines are the lines
connecting the origin
points with the
destination points.

Speed and delay survey
Survey is carried on the existing road system
are needed for assessing the loses (in travel time)
caused by the congested condition.
The survey is convenient done by moving
observer method.
A car driven along the road ,noting its travel
time ,number of vehicles met with in opposite
direction and the number of vehicle overtaken.
About six runs are needed to average out .the
survey gives the journey speed and volume.

Speed and delay survey
Separate recording sheets are
maintained for each direction of movement for a
specified time interval.
After collecting the field date major
work remains of the office computations and
analysis, by tracking each vehicle number and its
time of entering and leaving the cordoned area.
This method is quite easy and quick as
far as the field work is concerned.

Methods of speed and delay study
Floating car or riding check method
License plate or vehicle number method
Interview technique
Elevation observation
Photographic techniques

Floating car or riding check
method
A text vehicle is driven over a given course of travel at a
approximate average speed in the traffic stream
One observer is seated in the floating car with two stop
watches.
One stop watch is used to record the time at various
control point like intersection, bridges etc.
The other stop watch is used to find the duration of
individual delay. www.Annauniversityplus.com

Floating car or riding check method
The time, location and cause of these delays are recorded by
the second observer on suitable tabular column.
The number of vehicle overtaking the test vehicle and that
overtaken by the test vehicle are noted in each trip.
The number of vehicle travelling in opposite direction in each
trip is noted by fourth observer.
In mixed traffic more number of observer are required.
More number of trips are recorded.

The average journey time t is given by
t = tw-(ny/q)
q= na +ny/(ta +tw)
q = flow of vehicle(volume per min)
na =average number of vehicle counted in direction of
stream when the test vehicle travels in opposite direction.
ny = average number of vehicle overtaking the test vehicle
minus the number of vehicle over taken by the test vehicle.
Tw = average journey time ,in minute when the test vehicle
is travelling with the stream
Ta = average journey time ,in minute when the test vehicle
is running against the stream

Time space diagram

Highway Capacity and Level of Service
• Road capacity is the maximum
potential capacity of a given roadway. It can
be expressed in terms of vehicles per hour or
per day.
• road capacity for the purpose of limiting traffic
to reduce congestion or environmental
problems.

• Typically three parameters are used under this and they are
speed and travel time, density, and delay.
• One of the important measures of service quality is the
amount of time spent in travel. Therefore, speed and travel
time are considered to be more effective in defining LOS of
a facility.
• Density gives the proximity of other vehicles in the stream.
Since it affects the ability of the driver to plan in the traffic
stream, it is also used to describe LOS.
• Delay is a term that describes excess or unexpected time
spent in travel. Many specific delay measures are defined
and used as MOE's in the highway capacity manual.

Factors affecting level of service
1. Speed and travel time
2. Traffic interruptions/restrictions
3. Freedom to travel with desired speed
4. Driver comfort and convenience
5. Operating cost

Highway Capacity Manual(HCM)
• Travel speed and volume
by capacity ratio (v/c ratio)
to distinguish between
various levels of service.
– The value of v/c ratio can
vary between 0 and 1.
Depending upon then travel
speed and v/c ratio, HCM
has defined six levels of
service, level A to level F
based on a graph between
operating speed and v/c
ratio

Level of service A
• Level of service A represents the zone of free flow.
• Here the traffic volume will be less, traffic will be
experiencing free flow also.
• The drivers will be having the complete freedom to
choose their desired speed.
• Even at maximum density, for this LOS the average
spacing between vehicles is 167 m.
• Lane changes within the traffic stream, as well as
merging and diverging movements, are made
relatively easy.
• The effect of minor incidents and point breakdowns
are easily aborted at this level.www.Annauniversityplus.com

Level of service B
Level of service B represents zone of reasonably
free flow. Free flow speeds are still maintained at this
level of service.
The drivers freedom to choose their desired
speed is only slightly restricted.
The lowest average spacing between vehicles is
about 100 m.
The effects of small incidents and point
breakdowns are still easily contained.

Level of service C
• At level of service C, the presence of other vehicles
begins to restrict the maneuverability within the traffic
stream.
• Average speeds remain at or near the free flow speed
level, but significant increase in driver alertness is
required at this level.
• Minimum average spacing between the vehicles is in
the range of 67 m.
• Queues may be expected to form behind any
significant blockage.

Level of service D
• At level of service D, the average speeds begin to
decline with increasing flows. Freedom to maneuver
within the traffic stream is noticeably restricted.
• At this level, density deteriorates more quickly with
flow.
• The spacing between the vehicles is about 50 m.
• As the traffic stream has little space to absorb
disruptions, minor incidents can lead to queuing of
vehicles.

Level of service E
Level of service E define operation at capacity.
At this level, the stream reaches it's maximum
density limit.
There will be no usable gaps in the stream
and even slight disruptions will cause a
breakdown, with queues forming rapidly behind
the disruption.
Maneuvering within the traffic stream
becomes extremely difficult.

Level of service F
• Level of service F describes conditions in a queue that
has formed behind a point of breakdown or disruption.
• As vehicles shue through the queue, there may be
periods when they move quickly, and others when they
are stopped completely.
• Thus this level of service is used to describe the point
of breakdown as well, even though operations
downstream of such a breakdown may appear good.
• Level of service F represents the region of forced flow,
having low speed .

Uninterrupted flow
• Uninterrupted flow is the flow of traffic in which there is no
obstructions to the movement of vehicles along the road .
• Freeway is one example for this type of Facility .
• In a freeway, when a vehicle enters a freeway, there is no
need for the vehicle to stop anywhere till it leaves the
freeway.
• There are three sections in a freeway - basic unit, weaving
section and ramps(on/off).
• Vehicles will be entering the freeway through ramps.
Ramps used for entering the freeway is called on-ramps
and those used for exiting the freeway are called off-ramps.
• Freeways generally have 4, 6, or 8 lane alignments. Multi
lanes also provide uninterrupted flow. In many roads, there
will be signalized as well as un signalized Intersections.

Interrupted flow
• Interrupted flow refers to the condition when
• This is experienced in signalized intersections, un signalized
intersections, arterials etc
• At signalized intersections, there will be some kind of active
control and the vehicle will have to stop or sometimes to
reduce its speed and the flow of traffic is interrupted.
• Thus the capacity is defined in terms of control delay ie
sec/veh.
• Arterials are roads of long stretches with many intersections in
between and obviously there will be interruption to the flow of
traffic.
• Here, the capacity is expressed in terms of average travel
speed.

• Example for pedestrian facility is a provision of subway exclusively
for the use of pedestrians.
• Here, the capacity may be expressed in terms of number of
passengers.
• In bus transit system, the buses has to stop at the bus bays and also
it has to share the road with the other vehicles. Hence the capacity
will be affected by the control characteristics and the traffic
conditions prevailing in the road.
• Since trains have exclusive right of way, the capacity is strictly
governed by the control characteristics.
• It has two types of capacities - line capacity and station capacity.
Line capacity is based on the number of tracks available between
two stations.
• Station capacity refers to the facilities available in the
• platform of the station,vand other facilities.

• For uninterrupted flow of traffic, measure of
effectiveness (MOE) is density in freeways.
Speed also becomes important in two-lane
highways and multilane highways.
• In the case of interrupted flow, MOE is delay.
The delay of travel time becomes an
important factor in calculating the capacity.

Highway Capacity
1. Traffic conditions:
It refers to the traffic composition in the road such
as the mix of cars, trucks, buses etc in the stream. It also
include peaking characteristics, proportions of turning
movements at intersections etc.
2. Road way characteristics:
This points out to the geometric characteristics of the
road. These include lane width, shoulder width, lane
configuration, horizontal alignment and vertical alignment.
3. Control conditions:
This primarily applies to surface facilities and often refer to
the signals at intersections etc.

Again capacity can be defined for a point or uniform
section.
Capacity is estimated for segments having uniform
conditions.
Points where these conditions change represent the
boundaries where separate analysis may be
required.
Capacity is the maximum flow rate that a facility can
afford. This maximum flow rate is taken for the
worst 15 minutes of the peak hours while finding
out the capacity.

Capacity is measured as a reasonably expected
value and not the maximum flow rate ever
observed in the facility.
This is because the measured capacity at a single
location will show significant variation from
day to day. Further, local driving habits also
produce variations in the observed capacity.

Parking
• Parking is one of the major problems that is created by
the increasing road traffic.
• It is an impact of transport development.
• The availability of less space in urban areas has
increased the demand for parking space especially in
areas like Central business district.
• This affects the mode choice also.
• This has a great economical impact.

Parking studies
• Before taking any measures for the betterment of
conditions, data regarding availability of parking
space, extent of its usage and parking demand is
essential.
• It is also required to estimate the parking fares
also.
• Parking surveys are intended to provide all these
information.
• Since the duration of parking varies with different
vehicles, several statistics are used to access the
parking need.

Parking statistics
• Parking accumulation
• Parking volume
• Parking load
• Average parking duration
• Parking turnover
• Parking index

Parking statistics
Parking accumulation:
– It is defined as the
instant of time.
number of vehicles
parked at a given
– Normally this is
expressed by
accumulation curve.
– Accumulation curve is
the graph obtained
by plotting the
number of bays
occupied with respect
to time.

Parking volume:
– Parking volume is the total number of vehicles parked at
a given duration of time.
– This does not account for repetition of vehicles.
– The actual volume of vehicles entered in the area is
recorded.
Parking load :
– Parking load gives the area under the accumulation
curve.
– It can be obtained by multiplying the number of vehicles
occupying the parking area at each time interval with the
time interval.
– It is expressed as vehicle hours.

Average parking duration:
– It is the ratio of total vehicle hours to the number
of vehicles parked
AVD=Parking Load / Parking volume
Parking turnover:
– It is the ratio of number of vehicles parked in a
duration to the number of parking bays available.
– This can be expressed as number of vehicles per
bay per time duration.
Parking turnover =Parking volume /Number of bay

Parking index:
– Parking index is also called occupancy or
efficiency.
– It is defined as the ratio of number of bays
occupied in a time duration to the total space
available.
– It gives an aggregate measure of how effectively
the parking space is utilized
Parking Index= (Parking load /Parking capacity)

Example
• To illustrate the various measures, consider a
small example in figure , which shows the
duration for which each of the bays are
occupied(shaded portion).
• Now the accumulation graph can be plotted by
simply noting the number of bays occupied at
time interval of 15, 30, 45 etc. minutes as
shown in the figure

• Parking volume
= 5 vehicles.
• Parking load
= (1 + 2 + 1 + 0 + 1 + 2 + 3 + 1
) x 15/60
= 2.75 veh per hour
• Average parking duration
= 2.75/5= 33minutes.
• Parking turnover
=5veh /2hour/3bay
= 0.83 veh/hr/bay.
• Parking index
= {2.75 /(3 x2)] x 100=
45.83%

Parking surveys
• Parking surveys are conducted to collect the
parking statistics.
The most common parking surveys
conducted are
• In-out survey,
• Fixed period sampling and
• License plate method of survey.

In-out survey:
₋ The occupancy count in the selected parking
space is taken at the beginning.
– Then the number of vehicles that enter the
parking space for a particular time interval is
counted.
– The number of vehicles that leave the parking
space is also taken.
– The final occupancy in the parking space is also
taken.

– But we wont get any data regarding the time
duration for which a particular vehicle used that
parking lot.
– Parking duration and turn over is not obtained.
– Hence we cannot estimate the parking fare from
this survey.
– Here the labor required is very less.

Fixed period sampling:
–This is almost similar to in-out survey.
–All vehicles are counted at the beginning of
the survey.
–Then after a fixed time interval that may
vary between 15 minutes to 1 hour, the
count is again taken.
–Here there are chances of missing the
number of vehicles that were parked for a
short duration.

LIC ENCE P LATE M ETHO D
– This results in the most accurate and realistic data.
– every parking space is monitored at a continuous
interval of 15 minutes or so and the license plate
number is noted down.
– This will give the data regarding the duration for
which a particular vehicle was using the parking
bay.
– This will help in calculating the fare because fare is
estimated based on the duration for which the
vehicle was parked.
– But this method is very labor intensive.

Ill effects of parking
Congestion
Accidents
Environmental pollution
Obstruction to fire fighting operations

Ill effects of parking
• Congestion:
– Parking takes considerable street space leading to the
lowering of the road capacity.
– speed will be reduced, journey time and delay will
increase.
– The operational cost of the vehicle increases leading
to great economical loss to the community.
• Accidents:
– Careless monitoring of parking and un parking leads
to accidents which are referred to as parking
accidents.
– accidents occur while driving out a car from the
parking area
– careless opening of the doors of parked cars,

• Environmental pollution:
– They also cause pollution to the environment
because stopping and starting of vehicles while
parking and un parking results in noise and fumes.
– They also affect the aesthetic beauty of the
buildings
• Obstruction to fire fighting operations:
– Parked vehicles may obstruct the movement of
firefighting vehicles.
– Sometimes they block access to hydrants and
access to buildings.

Parking requirements
– There are some minimum parking
requirements for different types of building.
– For residential plot area less than 300 sq.m
require only community parking space.
– For residential plot area from 500 to 1000
sq.m, minimum one-fourth of the open area
should be reserved for parking.

Parking requirements
– Offices may require atleast one space for every
70 sq.m as parking area.
– One parking space is enough for 10 seats in a
restaurant where as theatres and cinema halls
need to keep only 1 parking space for 20 seats.
– Thus, the parking requirements are different
for different land use zones.

Types of parking
On street parking
 Parallel parking
30 ⁰ parking
45 ⁰ parking
60 ⁰ parking
Right angle parking
Off street parking

On street parking
–On street parking means the vehicles are
parked on the sides of the street itself.
–This will be usually controlled by
government agencies itself.
–As per IRC the standard dimensions of a car
is taken as 5 x2.5 metres and that for a
truck is 3.75 x7.5 metres

Parallel parking
– The vehicles are parked along the
length of the road.
– there is no backward movement
– most safest parking from the
accident
– it consumes the maximum kerb
length
– only a minimum number of
vehicles can be parked for a
given kerb length.
– least obstruction to the on-going
traffic on the road since least
road width is used.www.Annauniversityplus.com

30⁰ parking
– The vehicles are
parked at 30 with
respect to the road
alignment.
– More vehicles can be
parked compared to
parallel parking.
– Also there is better
maneuverability.
– Delay caused to the
traffic is also
minimum www.Annauniversityplus.com

45⁰ parking
• As the angle of parking
increases, more number
of vehicles can be
parked.
• compared to parallel
parking and thirty
degree parking, more
number of vehicles can
be accommodated in
this type of parking.

60⁰ parking
• The vehicles are parked
at 60 to the direction of
road.
• More number of
vehicles can be
accommodated in this
parking type

Right angle parking:
• The vehicles are parked
perpendicular to the direction of
the road.
• maximum width kerb length
required is very little.
• the vehicles need complex
maneuvering
• this may cause severe accidents.
• This causes obstruction to the
road traffic particularly if the road
width is less.
• it can accommodate maximum
number of vehicles for a given
kerb length. www.Annauniversityplus.com

Off street parking
– In many urban centres,
some areas are allotted
for parking which will be
at some distance away
from the main stream of
traffic.
– They may be operated by
either public agencies or
private firms.

Traffic signal design-I

Objective
Movements of
traffic in different
directions is solved
by time sharing of
the principle.

Advantages of traffic signal
– Orderly movement of traffic
– An increased capacity of the intersection
– Reduce the frequency accident
– Continuous movement of traffic with defined
speed
– Dispenses the police and economical
– Requires only simple geometric design.

Disadvantages of the signalized
intersection
– It affects larger stopped delays
– Design requires complex considerations.
– Accident frequently
– Excess delay during peak hours
– Drivers prefer less safe route due to delay

Signal indication
• British practice
– Red
– Red /amber
– Green
– Amber
• American practice
– Red
– Green
– Yellow
• Indian practice
– Red
– green
– Amber www.Annauniversityplus.com

OBJECTIVES
• Amber period of 2 seconds
• Lenses are normally of two sizes of 200 mm
dia and 300 mm dia
• Large size are used for 85 th percentile
approach speed exceeds 65 KPH
• The height of the signals shall be such that
when erected ,the centre of amber shall be
not less than 2.4 m nor more than 4.0 m
above the carriageway level

• Primary signal is installed at 0.9 m from the
stop line and secondary signals is usually
installed if there is a central island
• A secondary signal is commonly installed
opposite to first primary signal on the back of
the primary signal intended for opposite
traffic
• A minimum two signal faces to be provided

Minimum visibility distance

Definition
• Cycle: A signal cycle is one complete rotation
through all of the indications provided.
• Cycle length: Cycle length is the time in
seconds that it takes a signal to complete one
full cycle of indications.
It indicates the time interval between
the starting of green signal till the next time
the green starts. It is denoted by C.

Phase diagram

• Interval: The change from one stage to another.
There are two types of intervals
–change interval
–clearance interval.
• Change interval is also called the yellow time
indicates the interval between the green and red
signal indications.
• Clearance interval is also called all red is included
after each yellow interval indicating a period
during which all signal faces show red
• It is used for clearing of the vehicles in the
intersection

• Green interval: It is the green indication for a
particular movement and is denoted by Gi.
This is the actual duration the green light of a
traffic signal is turned on.
• Red interval: It is the red indication for a
particular movement and is denoted by Ri.
This is the actual duration the red light of a
traffic signal is turned on.

• Lost time: It indicates the time during which the
intersection is not effectively utilized for any
movement.
• For example, when the signal for an approach
turns from red to green, the driver of the vehicle
which is in the front of the queue, will take some
time to perceive the signal (usually called as
reaction time) and some time will be lost here
before he moves.

• Phase: A phase is the green interval plus the
change and clearance intervals that follow it.
Thus, during green interval, non conflicting
movements are assigned.
• It allows a set of movements to flow and
safely halt the flow before the phase of
another set of movements start

Phase design
• The signal design procedure involves six major steps.
• They include the
– phase design,
– determination of amber time and clearance time,
– determination of cycle length,
– apportioning of green time,
– pedestrian crossing requirements, and
– the performance evaluation of the above design.

Two phase signals
• Two phase system is usually adopted if through
traffic is significant compared to the turning
movements.
• Traffic flow 3 and 4 are grouped in a single phase
and
• Traffic flow 1 and 2 are grouped in the second
phase.
• Flow 7 and 8 offer some conflicts and are called
permitted right turns.
• Needless to say that such phasing is possible only
if the turning movements are relatively low.
• if the turning movements are significant ,then a
four phase system is usually adopted.

Four phase signals
• Flow from each approach is put into a single
phase for avoiding all conflicts.
• The turning movements are comparable with
other movements
• When traffic and turning traffic need to share
same lane.
• This phase plan could be very inefficient when
turning movements are relatively low.

Standard Two Phase Operation
• The simplest type of signal phasing is the
standard two-phase operation.
• the major street approaches to an intersection
are served by one phase and the minor street
approaches are served by the second phase
• The two phase configuration is very efficient
and operates well under low volume
conditions but does not permit separate turn
phases.

INDIAN PRACTISE

AMERICAN PRACTISE

OPTIMUM CYCLE LENGTH
• Fixed time signals is to determine the cycle
time
• Cycle time should be least delay caused to the
traffic passing through the intersection
• If the cycle time is small the proportional of
time lost will be high resulting in insufficient
signal operation
• If the cycle time is high the proportional of
time lost will be small resulting in more
efficient signal operation

Optimum cycle time
• Optimum cycle time for intersection with
respect to cycle time
Co = (1.5 L + 5)/1-Y
Co= optimum cycle time
L= total lost time per cycle
Y=y1 +y2+…+yn= (q/s) i.e maximum of y values
q= traffic flow
S=saturation flow(maximum flow)

Rate of flow against time
• Soon as green signal is
given the rate of
discharge begins to pick
up and some time the
time is lost before the
flow reaches the
maximum value
(saturated slow)
• At the terminal of green
phase the flow tends to
taper off involving the
lost timel = k +a - g

l = k +a – g
• l=lost time for the phase
• k=green time for the phase
• a=amber time for the phase
• b=number of vehicle discharger in a saturated
flow
• s=saturated flow
• g=effective green time=b/s

• If there are n phases in a cycle
• Starting delay be nl
• Total lost time L
• L= nl+R

Trial cycle period
• 15 min traffic count n1 and n2 on road 1 and 2
are noted during design peak hour.
• Trial cycle C1 seconds is assumed
• Number of cycle in 15 min is found by
(15 x 60)/C1
• Assuming the average head way is 2.5 seconds
• The green period G1 and G2 of road 1 and
road 2 is calculated by
G1=(2.5n1 x C1)/900
G2=(2.5n1 x C1)/900

• The amber period A1 and A2 are calculated or
assumed as 3 or 4 seconds
• The length C1’=(G1+G2+A1+A2)
• If the calculated length C1’ is approximately
equal to the assumed cycle length C1,the
design cycle is accepted
• Or the trail are repeated till the trial cycle
length equal to the calculated value

Problem
• The 15 min traffic count on cross road 1 and
21 during peak hours are observed as 178 and
142 vehicles per lane respectively in the
direction of heavier traffic flow. If the amber
times required are 3 and 2 sec for two loads
based on approach speed, design the signal
timing by trial cycle method. Assume an
average time headway of 2.5 sec during green
phase.

solution
• Assume a trial cycle C1 =50sec
• Number of cycle in 15 min = 900/50=18
• Average headway time =2.5 sec
• Green time foe road 1
• G1=(2.5 x 178 x 50)/900 =24.7 sec
• Green time foe road
• G2=(2.5 x 142 x 50)/900 =19.7sec
• Amber time A1 and A2 = 3 and 2 sec
• Total cycle length =24.7+19.7+3+2=49.4 sec
• Is lower than assumed cycle, try another cyclewww.Annauniversityplus.com

Trail ii
• Number of cycle in 15 min = 900/40=22.5
• G1=(2.5 x 178 x 40)/900 =19.8 sec
• G2=(2.5 x 142 x 40)/900 =15.8sec
• Total cycle length =19.8+15.8+3+2=40.6 sec
• Is lower than assumed cycle, try another cyclewww.Annauniversityplus.com

Trail iii
• Number of cycle in 15 min = 900/45=20
• G1=(2.5 x 178 x 45)/900 =22.25 sec
• G2=(2.5 x 142 x 45)/900 =17.75sec
• Total cycle length =12.25+17.75+3+2=45 sec

Design of pedestrian and traffic
signals by approximate method
• Amber period 2,3,4 sec are taken
• Pedestrian walking speed 1.2m per second
• Minimum red time
= pedestrian clearance time +initial
interval for pedestrian to start crossing
• Minimum green time
= pedestrian clearance time for cross road
+ initial interval to start by pedestrian-amber
period

• Minimum green time= red time for crossing -
amber time for cross road
• With pedestrian signal used ,Walk period is
not less than 7 sec
• When no pedestrian signal is used minimum
period of 5 sec is used as initial interval
• Actual green time is increased based on ratio

problem
• An isolated signal with pedestrian indications
is to be installed on the rioght angled
intersection with road 18 m wide and road B
12 m wide.the heaviest volumwe per hour for
each lane of road A and road B are 275 and
225 respectively.the approximate speed are 55
and 40 KMPH.design the timing of traffic and
pedestrian signals.

• Design of traffic signals
• Based on the approach speed amber period are
For road A with 55kmph Aa=4sec
For road B with 40kmph Ab=3sec
• Based on pedestrian walking speed of 1.2 m/sec
pedestrian clearance time
Road A = 18/1.2 =15 sec
Road A = 12/1.2 =10 sec
• Addition 7 sec for initial walk period

• Minimum red time period for road A
=15+7=22 sec
• Minimum red time period for road A
=10+7=17 sec
• Minimum green time based on pedestrian
criteria
• Road B=15+7-3 =19 sec
• Road A=10+7-4=13 sec

• Based on approach volume ,green time is
increased for road A with higher traffic volume
• Using relation
(Ga/Gb)= (nA/nB)
Ga and Gb are green time and nA and nB are
approach volume per lane
Ga= (nA/nB) xGb
=(275/225) x 19 = 23.2 sec
Total cycle = Ga + Aa + Ra = Ga + Aa + Gb + Ab
=23.2+4+19+3=49.3 secwww.Annauniversityplus.com

• Hence adopt 50sec
• Addition period =50-49.2 =0.8 sec
GA =23.2+0.44=-23.64 sec
Gb=19+0.36=19.36 sec
Ra=Gb+Ab=19.36+3=22.36 sec
Rb=Ga+Aa=19.36+4=27.64 sec

Road A
Road A
RoadB
RoadB
RoadB
RoadB
Road A
Road A
Phase 1
Phase 2
Design of Traffic Signals

Road A
Road A
RoadB
RoadB
RoadB
RoadB
Road A
Road A
Phase 1
Phase 2
Design of Pedestrian Signals
DONT
WALK
WALK
DONT
WALK
WALK

DONT
WALK
WALK

TRAFFIC CONTROL AIDS AND
STREET FURNITURES

STREET FURNITURES
• ROAD WAY DELINEATORS
• SAFETY BARRIERS
• BARRICADES AND CHANNELISER
• RAILING
• TRAFFIC SIGNS
• OVERHEAD TRAFFIC SIGNS
• TRAFFIC SIGNAL POSTS
• TRAFFIC IMPACT ATTENUATORS
• TRAFFIC AID POSTS
• SPEED BREAKERS
• HAZAED MARKERS AND OBJEXT MARKERS

ROAD WAY DELINEATORS
• Visual aids to the
drivers concerning
the alignment of
roads especially in
nights
• 80-100 CM HIGH
• Side facing -10cm

Hazard marker
Used to define the
obstructions like guard
rail and a abutment
adjacent to the carriage
way

Speed breaker
• Used near school,
university etc
• Painted with white road
paint to make them
visible at night

Speed marker

Guard rail
• Guiding pedestrian to
subway ,footbridge and
surface crossing
• Should be set back 500
mm from kerb

Safety barriers
• To prevent vehicle
accident
• Used in bridges
• Used to withstand the
impact of vehicle and
deflect the same
inwards.

Barricades
• Controlling and
diverting the traffic on
construction zones and
temporary diversion

Traffic cones
Stripes may be 10-15 cm
and are alternately in
reflectorised white and
orange or red

Litter bins
For collecting trash
thrown in away by the
road user

Road marking

Road marking
The road markings are defined as
lines, patterns, words or other devices, except
signs, applied or attached to the carriageway or
kerbs or to objects within or adjacent to the
carriageway, for controlling, warning, guiding
and informing the users.

Role of Road marking
The essential purpose of road markings is to
–Guide and control traffic on a highway.
–Serve as a psychological barrier
–To delineation of traffic path and its lateral
clearance from traffic hazards.
–ensure the safe, smooth and harmonious
flow of traffic.

Types of marking
Various types of road markings is to warn
the driver about the hazardous locations in the
road,
They are
–Transverse markings
–Object markings
– Special markings

Longitudinal markings
Placed along the direction of
traffic on the roadway surface
for the purpose of indicating to
the driver his proper position
on the roadway.
Provided for separating traffic
flow in the same direction
Predominant color used is white.
Yellow color is used to separate
the traffic flow in opposite
direction and also to separate
the pavement edges.

The lines can be either
broken, solid or
double solid.
Broken lines are
permissive in
character and allows
crossing with good
judgment, if traffic
situation permits.
Solid lines are
restrictive in
character and does
not allow crossing
except for entry or
exit from a side road

• Double solid lines indicate
strictness in restrictions and
should not be crossed except
in case of emergency.
• There can also be a
combination of solid and
broken lines. In such a case, a
solid line may be crossed with
good judgment, if the broken
line of the combination is
nearer to the direction of
travel. Vehicles from the
opposite directions are not
permitted to cross the line.

Types of longitudinal marking
Different types of longitudinal markings are
– centre line
– traffic lanes
– no passing zone
–warning lines
–border or edge lines
–bus lane markings
– cycle lane markings

Centre line marking
Centre line separates the
opposing stream of traffic
and facilitates their
movements.
Usually no centre line is
provided for roads having
width less than 5 m and for
roads having more than
four lanes.
The centre line may be marked
with either single broken
line, single solid line, double
broken line, or double solid
line depending upon the
road and traffic
requirements.

Center line marking for two lane
• On urban roads with less than four lanes, the centre
line may be single broken line segments of 3 m long
and 150 mm wide.
• The broken lines are placed with 4.5 m gaps
• On curves and near intersections gap shall be reduced
to 3 metres.

two traffic lanes
• On undivided urban roads with at least two
traffic lanes in each direction, the centre line
marking may be a single solid line of 150 mm
wide .
• The broken lines are placed with 4.5 m gaps

More than two traffic lane
Double solid line of 100 mm wide separated by
a space of 100 mm

Four lane road
• The centre barrier line marking for four lane road

Traffic lane lines
• The subdivision of wide carriageways into
separate lanes on either side of the carriage
way helps the driver to go straight and also
curbs the meandering tendency of the driver.

• At intersections, these traffic lane lines will
eliminate confusion and facilitates turning
movements.
• It help in increasing the capacity of the road in
addition ensuring more safety.
• Normally single broken lines of 100 mm width.

No passing zones
• No passing zones are
established on summit
curves, horizontal curves,
and on two lane and three
lane highways where
overtaking exercises are
prohibited because of low
sight distance.
• It may be marked by a solid
yellow line along the centre
or a double yellow line.

No passing zones
• In the case of a double yellow
line, the left hand element may
be a solid barrier line, the right
hand may be a either a broken
line or a solid line . These solid
lines are also called barrier
lines.
• When a solid line is to the right
of the broken line, the passing
restriction shall apply only to
the opposing traffic.

Warning lines
• Warning lines warn the
drivers about the obstruction
approaches.
• They are marked on
horizontal and vertical curves
where no overtaking zones.
• They are broken lines with 6
m length and 3 m gap.
• A minimum of seven line
segments should be provided.

Edge lines
• Edge lines indicate edges of rural
roads which have no kerbs to
delineate the limits upto which
the driver can safely venture.
• They should be at least 150 mm
from the actual edge of the
pavement. They are painted in
yellow or white.
• All the lines should be preferably
light reflective, so that they will
be visible during night also.
• Improved night visibility may
also be obtained by the use of
minute glass beads embedded in
the pavement marking materials
to produce a retro reflective
surface. www.Annauniversityplus.com

Transverse markings
• Transverse markings are marked across the
direction of traffic.
• They are marked at intersections etc.
• The type of road marking for a particular
intersection depends on several variables such
as speed characteristics of traffic, availability
of space etc.
• Stop line markings, markings for pedestrian
crossing, direction arrows, etc.

Stop line
• Stop line indicates the
position beyond which the
vehicles should not proceed
when required to stop by
control devices like signals
or by traffic police.
• They should be placed
either parallel to the
intersecting roadway or at
right angles to the direction
of approaching vehicles.www.Annauniversityplus.com

Pedestrian crossings
Provided at places where the conflict
between vehicular and pedestrian traffic is
severe.
The site should be selected that there is less
inconvenience to the pedestrians and also
the vehicles are not interrupted too much.

Pedestral crossing
At intersections, it should be
preceded by a stop line at a
distance of 2 to 3m for un
signalized intersections and
at a distance of 1 m for
signalized intersections.
Most commonly used pattern
is Zebra crossing consisting
of equally spaced white
strips of 500 mm wide.

Directional arrows
Should used to guide the
drivers in advance over
the correct lane to be
taken while approaching
busy intersections.
The arrows should be
elongated in the direction
of traffic for adequate
visibility.
The dimensions of these
arrows are also very
important.

Object marking
• Physical obstructions in
a carriageway like traffic
island or obstructions
near carriageway like
signal posts, pier etc.
cause serious hazard to
the flow of traffic and
should be adequately
marked.
• They may be marked on
the objects adjacent to
the carriageway.

Objects within the carriageway
• The obstructions within the carriageway such as
traffic islands, raised medians, etc. may be
marked by not less than five alternate black and
yellow stripes.
• The stripes should slope forward at an angle of 45
with respect to the direction of traffic.
• These stripes shall be uniform and should not be
less than 100 m wide so as to provide sufficient
visibility.
• Poles close to the carriageway should be painted
in alternate black and white up to a height of 1.25
m above the road level.www.Annauniversityplus.com

Objects adjacent to carriageway
• Other objects such as guard stones, drums, guard rails etc.
where chances of vehicles hitting them are only when vehicle
runs on the carriageway should be painted in solid white.
• Kerbs of all islands located in the line of traffic flow shall be
painted with either alternating black and white stripes of 500
mm wide or black and white stripes of same width.

Word messages
• word message on road surface may also be
conveyed by Information to guide, regulate, or
warn the road user
• capital letters.
• shall not consist of more than three words for
any message.
• STOP, SLOW, SCHOOL, RIGHT TURN ONLY etc.
• is elongated so that driver looking at the road
surface at a low angle can also read them
easily. www.Annauniversityplus.com

Parking
• The marking of the parking space limits on urban roads
promotes more efficient use of the parking spaces tends to
prevent encroachment on places like bus stops where parking
is undesirable.
• space limitations should be indicated with markings that are
solid white lines 100 mm wide.
• Words TAXI, CARS, SCOOTERS etc. may also be written if the
parking area is specific for any particular type of vehicle.
• To indicate parking restriction, kerb or carriage way marking
of continuous yellow line 100 mm wide covering the top of
kerb or carriageway close to it may be used.

Hazardous location
Wherever there is a change
in the width of the road,
or any hazardous
location in the road, the
driver should be warned
about this situation with
the help of suitable road
markings.
Road markings showing the
width transition in the
carriageway should be of
100 mm width.

Highway lighting

PURPOSE
• It provides more
visibility
• It helps the vehicles and
pedestrians to move
safely
• It reduces the accidents
• It increases the security
in inter sections
• It provides attractive
landscape during night
hours.

FACTORS INFLUENCE NIGHT VISIBILITY
• Amount and distribution of light flux from lamps
• Size of object
• Brightness of object
• Brightness of background
• Reflecting characteristic of pavement surface
• Glare on the eyes of the driver
• Time availability to see an object

DESIGN FACTOR OF HIGHWAY
LIGHTING
• Lamps
• Luminaries distribution of light
• Spacing of lighting units
• Height and over hang of mounting
• Lateral placement
• Lighting layout

LAMPS
• Filaments
• Florescent light
• Sodium vapour light
• mercury vapour light
Choice depends on
type ,
size,
colour,
distribution of light
brightness

Luminaries distribution of light
• Proper distribution of light
• Distribution should be downwards so that
high percentage of light is used to illuminate
the pavement.
• Uniformity of pavement distribution.

Types of luminaire distribution

• Indian standard recommends an average level
of illumination of 30 lux on important roads
carrying fast traffic and 15 lux on main roads
• The ratio of minimum to average illumination
is 0.4

Height and overhang mounting
• Mounting height ranging from 6 m to 10m
• Minimum vertical clearance required for
Eletric power limit upto 650 volts has been
specified as 6m

LIGHTING LAYOUTS

Spacing =30 to 60 m

Lighting layout

Spacing calculation
Spacing=
(lamp lumen x coefficient of utilisation x
maintence factor)/averagr lux x width of road

PROBLEM
• Design a lighting system for the following
condition
• Street width = 15m
• Mounting height = 7.5 m
• Lamp sixe =6000 lumen
• Luminaire type =II
• Calculate the spacing between lighting units to
produce average lux =6.0

SOLUTION
Ratio of Pavement width / mounting height =
15/7.5 =2
Coefficient of utilization =0.44 (from graph)
Assume maintenance factor =0.8
Spacing =(6000 x0.44 x 0.8)/6 x 15 =23.2 m

Ce2026 traffic engineering and management notes

More Related Content

What's hot (20)

Similar to Ce2026 traffic engineering and management notes (20)

More from Nayana 54321 (19)

Recently uploaded (20)

Ce2026 traffic engineering and management notes