Chapter 2 traffic studies

Chapter-2
TRAFFIC STUDIES
Prepared By: Ankit N Patel
Traffic Engineering
BITS Edu
Campus
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Traffic Studies
.
Traffic studies are carried out to analyze the traffic characteristics.
These studies helps in deciding the geometric design features traffic
control for safe and efficient traffic movement.
•The various traffic survey studies generally carried out are:
 Traffic volume study
 Speed study
 Spot speed study
 Speed and delay study
 Origin and destination study
 Traffic flow characteristics
 Traffic capacity study
 Parking study
 Accident studies
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2

Traffic Volume Study
 It is the number of vehicles crossing a section of road per unit time
at any selected period.
 It is used as a quantity measure of flow: the commonly units are
vehicles/day or vehicles/hour
Object and Uses of Traffic Volume Study:
 It is generally accepted as a true measure of the relative importance
of roads and in deciding the priority for improvement and
expansion.
 It is used in planning, traffic operation and control of existing
facilities and also for planning the new facilities.
 It is used in the analysis of traffic patterns and trends.
 Useful in structural design of pavement
 Pedestrian traffic volume study is used for planning side walk,
cross walks, subway and pedestrian signals.
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3

Scopes of Volume Study
SCOPES
Design
Planning
Improvement
Dynamic
Traffic
Management
Estimating
Highway
Use
Computing
Accident
Rates
Traffic
Stream
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Main Methods of Counting
• 1. Direct Method
• 2. Indirect Method
Manual Counting
Method
• 1. Contact System
• 2. Contact-less System
Automatic
Counting Method
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Manual Method
counts are typically used to gather data for determination of vehicle
classification, turning movements, direction of travel, pedestrian
movements, or vehicle occupancy. Most applications of manual counts
require small samples of data at any given location.
Manual counts are sometimes used when the effort and expense of
automated equipment are not justified. Manual counts are necessary
when automatic equipment is not available. Manual counts are
typically used for periods of less than a day. Normal intervals for a
manual count are 5, 10, or 15 minutes. Traffic counts during a Monday
morning rush hour and a Friday evening rush hour may show
exceptionally high volumes and are not normally used in analysis;
therefore, counts are usually conducted on a Tuesday, Wednesday, or
Thursday.
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Manual counts
• A manual classified count (MCC) involves counting all the
vehicles passing a selected location on a road for a pre-determined
period of time.
• The count is conducted by persons standing at the roadside and
recording passing vehicles on a form, hence the term “manual
traffic count”. This distinguishes it from counts by machines that
can record passing vehicles automatically, which are know as
“automatic traffic counts”.
• The count records individual vehicles by categories (i.e. a truck or
car) and the direction they are travelling in. This is the reason it is
called a ‘classified count’.
BITS Edu Campus Prof. Ankit Patel 7

 Employs a field team to count and classify traffic volume.
Procedure
 No. of observers required depends upon no. of Lanes and
type of information required.
 More desirable to record traffic in each direction of travel
by posting separate observers for each direction.
 For all-day counts ,work in three shifts can be arranged.
 Data is recorded by Five- dash system. (IIII)
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Equipments for manual counts
• Watch
• clip board
• Pencil, rubber, shapner
• Data sheet

Manual Count Recording Methods
• Tally Sheets

Tally Sheets
• Recording data onto tally sheets is the
simplest means of conducting manual counts.
The data can be recorded with a tick mark on
a pre-prepared field form. A watch or
stopwatch is necessary to measure the desired
count interval.

Survey Procedure

Vehicle Type Tally
Car
CNG
Bus
Motorcycles
NMT

 Details such as vehicle classification and no. of occupants can
be obtained.
 Records Turning movement data of vehicles at intersections.
 Analyzing traffic characteristics in unusual conditions such as
adverse weather conditions, traffic breakdowns, temporary
closure of any lane of highway etc.
 Comparatively cheaper method of counting.
 Data accumulated by manual methods are easy to analyze.
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 Not practicable to have manual count for 24 hrs of the day
and throughout the year.
 Counts of remote areas is possible by automatic devices.
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Automatic Counting Method

Automatic Counting Methods
 An automatic survey involves placing a tube or loop across a road
which is connected to a box containing the means for storing the
information.
 In this method, vehicles are counted automatically without any
human involvement.
 There are two techniques of automatic counting:
 a) Contact system based on pneumatic, mechanical, magnetic or
b)Contactless system based on electrical/optical,
ultrasound/infrared radar, micro wave, CCTV/video image
processing method etc.

Automatic Method
 The automatic count method provides a means for gathering large
amounts of traffic data. Automatic counts are usually taken in 1-
hour intervals for each 24-hour period.
 The counts may extend for a week, month, or year. When the counts
are recorded for each 24-hour time period, the peak flow period can
be identified.
 Automatic counts are recorded using one of three methods:
portable counters, permanent counters, and videotape
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Automatic Method
Portable Counters
Portable counting is a form of manual observation. Portable counters
serve the same purpose as manual counts but with automatic counting
equipment. The period of data collection using this method is usually
longer than when using manual counts. The portable counter method is
mainly used for 24-hour counts.
Pneumatic road tubes are used to conduct this method of automatic
counts Specific information pertaining to pneumatic road tubes can be
found in the users’ manual.
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20

Automatic Method
Permanent Counters
Permanent counters are used when long-term counts are to be
conducted. The counts could be performed every day for a year or
more. The data collected may be used to monitor and evaluate traffic
volumes and trends over a long period of time.
Videotape or Videography
Observers can record count data by videotaping traffic. Traffic
volumes can be counted by viewing videotapes recorded with a
camera at a collection site. A digital clock in the video image can
prove useful in noting time intervals.
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Pneumatic road tube
Pneumatic road tube sensors send a burst of air pressure along a rubber tube
when a vehicle's tires pass over the tube.
Figure : Pneumatic Road Tube 23
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Pneumatic Tubes

Bending plate
A weight pad attached to a metal plate embedded in the road to measure axel weight
and speed. It is an expensive device and requires alteration to the road bed.
Figure : Bending Plate 25BITS Edu Campus Prof. Ankit Patel

Equipments Used For Automatic Counting Method:
1.Pnematic Tubes 2. Weigh-In-Motion Sensor Types
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3. Vehicles counting by video camera (a) 3. Vehicles counting by video camera (b)
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4. Traffic counters
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7. Bending plate and pneumatic road tube 8. Automatic traffic recorders
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Factors affecting vehicle counting:
Weather conditions.
Purpose of the traffic counting.
Method of traffic counting.
Location of the counting sites.
Traffic flow level.
Road type.
Traffic composition.
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 Traffic Flow Maps:
 Show volume along various routes by using bands
proportional to traffic volume carried.
 Thickness of lines represent traffic volume.
 Intersection Flow Diagrams
 Give direction and volume of traffic through an intersection.
 Trend charts
 Shows the hourly , daily or monthly changes in volume
through an area.
 Useful for planning future expansion, design and regulation. 31

 Annual Average Daily Traffic(AADT)
 The total yearly volume divided by number of days in the year.
 Average Daily Traffic(ADT)
 The total volume during a given time period, in whole days
greater than one day and less than one year, divided by number
of days in that time period.
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Passenger Car Unit
The different vehicle classes have a wide range of statics
characteristics and dynamic characteristics, apart from these the driver
behavior of the different vehicle classes is also found to vary
considerable. Therefore mixed traffic flow characteristics are very
much complex when compare to homogeneous traffic and it is difficult
to estimate the traffic volume, capacity of roadway under the mixed
traffic flow, unless the different vehicle classes are converted to one
common standard vehicle unit.
•Therefore it is a common practice to consider the passenger car as the
standard vehicle unit to convert the other vehicle classes and this unit
is called passenger car unit PCU.
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Passenger Car unit (PCU) :-
It is a common practice to consider the passenger
car as the standard vehicle unit to convert the
other vehicle classes and this unit is called
Passenger car unit or PCU.
Thus in mixed traffic flow, the traffic volume &
capacity are generally expressed as PCU per hour
or PCU/lane/hour & the traffic density as PCU per
kilometer length of lane.

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Factor affecting Passenger Car Unit
 Vehicle characteristics
 Speed distribution of the mixed traffic stream, volume to capacity
ratio.
 Roadway characteristics.
 Regulation and control of traffic.
 Environmental and climatic conditions.
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 Spot Speed
 Instantaneous speed of a vehicle at a specified
location.
 Average Speed
 Average of the spot speeds of all vehicles passing a
given point on the highway.
 Running Speed
 Average speed maintained by a vehicle over a given
course while the vehicle is in motion.
 Running speed= Length of course / Running time
= Length of course /( Journey time- Delays)
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 Journey speed
 Also known as overall travel speed
 It is the effective speed between two points. It is the distance
between two points divided by the total time taken by the
vehicle to complete the journey ,including all delays.
 Journey speed = Distance/ Total journey Time (including
Delays).
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Speed and Delay Study

The methods available for measuring spot speed can be
grouped as
 Those observations that require time taken by a vehicle to
cover a known distance.
 It consist of
 long base methods- vehicles are timed over a long distance.
 Short base methods- vehicles are timed over a Short distance,
say about 2m.
 Radar Speedometer which automatically records
instantaneous speed.
 Photographic method.
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I). Those observations that require time taken by a vehicle to
cover a known distance.
 Long base methods
 Direct timing Procedure
 Enoscope
a)Direct timing Procedure
Simplest method
Two reference points are marked on the pavement at a
suitable distance apart and an observer starts and stops
stopwatch as a vehicle crosses these two marks.
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 From known distance and time, speed can be calculated.
 Disadvantage: errors due to parallax effect.
 Observation by two observers one at each reference points
 First observer standing at the point in which the vehicle pass
first, signals and seconds observer starts the stop watch. The
second observer stops the stop watch when he observes the same
vehicle passing the reference point.
 Disadvantage: reaction time of two observers.
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b). Enoscope
 Also known as mirror box
 L-shaped box, open at both ends ,with a mirror set
at 45 ˚ to the arms of the instrument.
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47
45˚
observer
vehicle
mirror
It bends the line of sight of the observer perpendicular to the
path of vehicle.

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 The instrument is placed directly opposite to the first reference
point and the observer stations himself at the second reference
point.
 Stop watch is started as soon as the vehicle passes the first point
and is stopped as soon as it passes the observer.
 If two enoscope is used, the observer stations himself midway
between two reference points.
 Advantages:
 Eliminates parallax error.
 Equipment is of low cost, simple and can set up easily
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 Works on the Doppler principle.
 Speed of a moving body is proportional to change in
frequency between the Radio wave transmitted to the
moving body and the radio wave received back.
 Instrument directly measures speed.
 Instrument is setup near the edge of carriageway at a
height of 1m.
 The speed meter is so kept that the angle between
direction of travel of vehicle and axis of transmission of
radio wave is as low as possible, say within 20˚.
 Speed of vehicles in both directions can be observed.
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 Time-lapse camera photography can be used.
 Photographs are taken at fixed intervals of time(say one
second per frame) on a special camera.
 By projecting the film on a screen, the passage of any
vehicle can be traced with reference to time.
 Images by video cameras can be also used.
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Data collection formBITS Edu Campus Prof. Ankit Patel 52

 Average speed of vehicles
 From spot speed data, distribution tables are prepared by
arranging the data in groups covering various speed ranges
and number of vehicles in each range.
 Arithmetic mean is the average speed.
 Cumulative speed of vehicles
 Graph is plotted with average values of each group on X-
axis and cumulative % of vehicles travelling at different
speeds.
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 85th percentile speed: Speed at or below 85 % of
vehicles are passing the point of highway.
 Only 15 % of vehicles exceed the speed at that spot.
 Drivers exceeding 85th percentile speed are considered to
drive faster than the safe speed. Hence 85th percentile
speed is adopted for Safe speed limit at that zone.
 50th percentile speed: median speed.
 15th percentile speed: represents the lower speed limit. 54

• Speed and delay studies give running speeds,
overall speeds, fluctuations in speed and delay
between two stations of a road spaced far apart.
They also give the information such as amount,
location, duration, frequency and causes of the
delay in the traffic stream. Various methods to
carry out speed and delay survey are:
• Floating Car method
• Licence Plate record method
• By Interview
• By Photography and videography

Methods of Speed and Delay Study
License Plate Method: it synchronized stop watches or voice
recording equipment are used. Observers are stationed at the entrance
and exit of a test section where information of travel time is required.
The timings and vehicle numbers are noted by the observers of the
selected sample. From the office computations , travel time of each
vehicle could be found. But the method does not give important detail
such as causes of delays and the duration and number of delays within
the test section.
Interview Technique: The work can be completed in a short time by
interviewing and collecting details from the road user spot. However
the data collected may not provide with all the details correctly.
Elevated observation and photographic technique: this are useful
for studying short test section like intersection. BITS Edu
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 In a transportation study, it is often necessary to know the
exact origin and destination of the trips. The information
yielded by O-D survey includes land-use of the zones of
origin and destination, household characteristics of the
trip making family, time of the day when journeys are
made, trip purpose and mode of travel.
INTRODUCTION
 Origin is defined as the place where the trip begins and
destination is defined as the place where the trip ends.
 Origin-Destination (OD) studies are an important tool
for transportation Professionals. OD studies are
conducted to understand the pattern of the movement
of Persons and goods in a particular area of interest
during a particular period of time (Wang, 1997).

O & D SURVEY
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 THE ORIGIN AND DESTINATION STUDY IS
CARRIED OUT MAINLY TO KNOW THE ORIGIN
AND DESTINATION OF VARIOUS VEHICALS .
 IN THIS STUDY THE DATA COLLECTED ARE,
NUMBER OF VEHICLES, THEIR ORIGIN AND
DESTINATION NUMBER OF PASSENGERS IN
EACH VEHICLE,ROUTE ETC.
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USE FOR O & D SURVEY
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 TO ESTABLISH PREFERENTIAL ROUTES FOR
VARIOUS CATEGORIES OF VEHICLES
 TO LOCATION OF NEW PROPOSED ROADS
 TO LOCATION OF PARKING PALACES
 TO LOCATE EXPRESSWAY
 TO REGULATE MOVEMENT OF HEAVY
VEHICLES
 TO LOCATE NEW BRIDGE AS PER TRAFFIC
DEMANDS
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METHOD OF O & D SURVEY
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 ROAD SIDE INTERVIEW SURVEYS
 HOME-INTERVIEW SURVEYS
 TELEPHONE SURVEYS
 TAXI SURVEYS
 POST CARD QUESTIONNAIRE SURVEYS
 REGISTRATION NUMBER SURVEY
 TAG SURVEY
 PUBLIC TRANSPORT SURVEY
 COMMERCIAL VEHICAL SURVEY
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ROAD SIDE INTERVIEW SURVEY
 IN THIS METHOD INTERVIEW STATIONS ARE
PREVIOUSLY DECISED ON THE ROADWAY.
 THE VEHICLES ARE STOPPED AT THE
INTERVIEW STATIONS BY A GROUP OF
PERSONS AND THE ANSWERS TO PRESCRIBED
QUESTIONNAIRE ARE COLLECETED ON THE
SPOT.
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INFORMATION COLLECTED
• PLACE AND TIME OF ORIGIN
• PLACE AND TIME OF DESTINATION
• ROUTE
• PURPOSE OF THE TRIP
• TYPES OF VEHICLES
• NUMBER OF PASSENGERS IN EACH VEHICLE
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ROAD SIDE INTERVIEW SURVEY
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Survey Questionnaire:
Location:
Date:
STANDARD FORMAT
Origin-Destination Survey
Questions
Please take a moment to answer a few questions
about your trip. Your responses will help determine the
need for improvements in this area.
·Where did your trip begin?
City/Town _____________________________
State ______
Zip _______
·What type of place is your trip start point?
❒ Primary Residence ❒ Workplace ❒ Store
❒ School (I am a student) ❒ Recreation Area
❒Other _________________________________

·Where did your trip end?
City/Town _____________________________
State ______
Zip __________
·What type of place is your trip end point?
❒ Primary Residence ❒ Workplace ❒ Store
❒ School (I am a student) ❒ Recreation Area
❒ Other _________________________________
·What was the purpose of your trip?
❒ Work Commute ❒ Business Related
❒ Shopping ❒ School (attend class)
❒Recreation ❒Other ___________________
·How many people were in the vehicle, including
the driver?
❒ 1 ❒ 2 ❒ 3 ❒ 4 ❒ 5 or
More

·What type of vehicle were you in?
❒ Passenger vehicle (car,
motorcycle,
SUV, pick-up truck, minivan)
❒ Commercial vehicle
❒Other
____________________________
·Do you regularly use this route?
❒ Yes
❒ No
·Please add any comments on
transportation you
May have.
Comments
____________________________
Thank you very much for your
cooperation!

ADVANTAGES & DISADVANTAGES
 ADVANTAGES :
 DATA IS COLLECTED QUICKLY IN SHORT
DURATION
 DISADVANTAGES:
 THE VEHICLES ARE STOPPED FOR INTERVIEW
AND THERE IS DELAY TO THE VEHICULAR
MOVEMENT
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HOME-INTERVIEW SURVEY
 IN THIS METHOD RANDOM SAMPLE OF 0.5 TO 10%
OF THE POPULATION IS SELECTED AND THE
RESIDENCE ARE VISITED BY THE TRAINED PERSON
WHO COLLECT THE TRAVEL DATA FROM EACH
MEMBOR OF THE HOUSEHOLD.
 DETAILD INFORMATION REGARDIND THE TRIPS
MADE BY THE MEMBERS IS OBTAINED ON THE SPOT.
 THE DATA COLLECTED MAY BE USEFUL EITHER FOR
PLANNING THE ROAD NETWORK AND OTHER
ROADWAY FACILITIES.
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HOME INTERVIEW SURVEY
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DATA COLLECTION
 NUMBER OF TRIP MADE
 THEIR ORIGIN & DESTINATION
 PURPASE OF TRIP
 TRAVEL MODE
 NUMBER OF RESIDENTS
 AGE
 VEHICLE OWNERSHIP
 NUMBER OF DRIVERS
 FAMILY INCOME
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ADVANTAGES & DISADVANTAGES
 ADVANTAGES:
 THE PROBLEM OF STOPPING OF VEHICLES AND
CONSEQUENT DIFFICULTIES ARE AVOIDED
 THE PRESENT TRAVEL NEEDS ARE CLEARLY
KNOWN AND THE ANALYSIS IS ALSO SIMPLE.
 ADDITIONAL DATA INCLUDING SOCIO-
ECONOMIC AND OTHER DETAILS MAY BE
COLLECTED SO AS TO BE USEFUL FOR
FORECASTING TRAFFIC AND TRANSPORTATION
GROWTH.
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TELEPHONE SURVEY
 THIS METHOD INTERVIEW ARE CONDUCT
WITH COMPUTER ASSISTED TELEPHONE
INTERVIEW TECHNOLOGY.
 A COMPLETE CATI SYSTEM MIGHT INCLUD
AUTOMATIC DAILING OF NEXT HOUSEHOLD TO
THE INTERVIEWER TO ASK THE NEST
QUESTION AUTOMATIC SKIPPING AND
BRANCHING WITHIN THE LIST OF QUESTIONS
DEPENDING ON THE ANSER TO THE PREVIOUS
QUESTION ,IMMEDIATE LOGIC CHECKS ON
ANSWER PROVIDED.
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TELEPHONE SURVEY
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 ADVANTAGES:
 SAVING THE TIME

 DISADVANTAGES:
INFORMATION RESPONCE NOT GOOD
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TELEPHONE SURVEY
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TAXI SURVEY
 LARGE URBAN AREAS USUALLY HAVE A
SIZEABLE AMOUNT OF TRAVEL BY TAXIS.
 IN SUCH CASES, A SEPARATE TAXI SURVEY IS
NECESSARY .
 THE SURVEY CONSISTS OF ISSUING
QUESTIONNAIRES OR LOG SHEETS TO THE
TAXI DRIVERS AND REQUESTING THEM TO
COMPLETE THE SAME.
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Prof. Ankit Patel
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TAXI SURVEY
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POST CARD
 IN THIS METHOD REPLY-PAID
QUESTIONNAIRES ARE HANDED OVER TO
EACH OF THE DRIVERS AT THE SURVEY POINTS
AND REQUISTING THEM TO COMPLETE THE
INFORMATION AND RETURN BY POST.
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 ADVANTAGES:
 THIS METHOD ARE SIMPLER AND CHEAPER
THAN MANY OTHERS.
 DISADVANTAGES:
 RESPONSE MAY NOT A GOOD
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POST CARD
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REGISTRATION NUMBER PLATE SURVEY
 REGISTRATION NUMBER PLATE SURVEY
CONSISTS OF NOTING THE REGISTRATION
NUMBER OF VEHICLES ENTERING OR LEAVING
AN AREA AT SURVEY POINTS LOCATED ON THE
CORDON LINE.
 BY MATCHING THE REGISTRATION NUMBER
OF THE VEHICLES AT THE POINT OF ENTRY
AND EXITFROM THE AREA , ONE IS ENABLED
TO IDENTIFY TWO POINTS ON THE PATHS OF
THE VEHICLES.
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 ADVANTAGES:
 WORK DOES NOT INTERFERE WITH THE
TRAFFIC IN ANY WAY.
 DISADVANTAGES:
 LARGE NUMBER OF OBSERVERS ARE NEEDED
 ANALYSIS OF THE RESULTS CAN BE
COMPLICATED.
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TAG SURVEY
 IN THIS METHOD AT EACH POINT WHERE THE
ROADS CROSS THE CORDON LINE, VEHICLES ARE
STOPPED AND A TAG IS AFFIXED ,USUALLY UNDER A
WIND SCREEN WIPER.
 THE TAGS FOR DIFFERENT SURVEYS STATIONS HAVE
DIFFERENT SHAPES/COLOUR TO IDENTIFY THE
SURVEY STATION.
 THE VEEHICLES ARE STOPPED AGAIN AT THE EXIT
POINTS WHERE THE TAGS ARE REMOVED.
 THE TIME OF ENTERING AND LEAVING THE AREA
MAY BE MARKED ON THE TAGS IN ORDER TO ENABLE
THE JOURNEY TIME TO BE DETERMINED
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 ADVANTAGES:
 THIS METHOD IS SIMPLE AND ERROR ARE NOT
VERY LARGE.
 DISADVANTAGES:
 IT IS NOT POSSIBLE TO HANDLE ALL THE
VEHICLES, SAMPLING MAY BE RESTORED TO
DONE.
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TAG SURVEY
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PUBLIC TRANSPORT SURVEYS
 IN THIS METHOD INTERVIWER MAY ENTER
THE VEHICLE AND CARRY OUT THE
INTERVIEWS WHEN THE VEHICLES IS IN
MOTION.
 POST-CARD QUESTIONNAIRES ELIMINATE
DELAYS, BUT ARE LIKELY TO EVOKE POOR
RESPONSE OR CONTAIN AN ELEMENT OR BIAS.
 THESE QUESTIONNAIRES MAY ALSO BE
COLLECTED AT THE STATIONS INSIDE THE
SURVEY AREA.
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PUBLIC TRANSPORT SURVEYS
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COMMERCIAL VEHICAL SURVEYS
 COMMERCIAL VEHICLE SURVEYS ARE
CONDUCTED TO OBTAIN INFORMATION ON
JOURNEYS MADE BY ALL COMMERCIAL
VEHICLES BASED WITHIN THE STUDY AREA.
 THE ADDRESSES OF THE VEHICLES
OPERATORS ARE OBTAINED AND THEY ARE
CONTACTED .
 FORM ARE ISSUED TO DRIVERS WITH A
REQUEST THAT THEY RECORD PARTICULARS
OF ALL THE TRIPS THEY WOULD MAKE.
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COMMERCIAL VEHICAL SURVEYS
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Introduction
One of the problems created by road traffic is parking. Not only do
vehicles require street space to move about, but also do they require
space to park where the occupants can be loaded and unloaded. The
period over which a car is parked is very great compared with the time it
is in motion. Every car owner would wish to park the car as closely as
possible to his destination so as to minimize his walking.
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Introduction
 Traveling vehicles at one time or another will
need to park for short or long times.
 Need for parking spaces is great in areas where
land uses include (business, residential, or
commercial).
 In high density areas spaces are very
expensive, thus the space provided for
automobiles usually has to be divided between
their movement and parking.

Effect of parking
 Congestion
 Accidents
 Obstruction to fire fighting operations
 Effect on environment
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1. Congestion: Parking takes considerable street space leading to the
lowering of the road capacity. Hence, speed will be reduced, journey
time and delay will also subsequently increase. The operational cost of
the vehicle increases leading to great economical loss to the
community.
2. Accidents: Careless maneuvering of parking and unparking leads to
accidents which are referred to as parking accidents. Common type of
parking accidents occur while driving out a car from the parking area,
careless opening of the doors of parked cars, and while bringing in the
vehicle to the parking lot for parking.
ILL EFFECT OF PARKING
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3. Environmental pollution: They also cause pollution to the
environment because stopping and starting of vehicles while parking
and unparking results in noise and fumes. They also affect the
aesthetic beauty of the buildings because cars parked at every
available space creates a feeling that building rises from a plinth of
cars.
4. Obstruction to fire fighting operations: Parked vehicles may
obstruct the movement of firefighting vehicles. Sometimes they block
access to hydrants and access to buildings.
ILL EFFECT OF PARKING
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General Terms of Parking
Facilities
 Parking Accumulation :-The total number of vehicles parked in an area at a
specified moment.
 Parking volume:-The number of vehicles parked in a particular area over a given
period of time. It is usually measured in vehicles per day. 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
also be obtained by simply multiplying the number of vehicles occupying the
parking area at each time interval with the time interval. It is expressed as vehicle
hours.
 Parking duration:-The length of time spent in a parking space.
 Parking turn over:-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.
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Parking system
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. Common types of on-street parking are as listed below. This
classification is based on the angle in which the vehicles are parked
with respect to the road alignment. As per IRC the standard
dimensions of a car is taken as 5× 2.5 meters and that for a truck is
3.75× 7.5 meters.
1. Parallel parking: The vehicles are parked along the length of the
road. Here there is no backward movement involved while parking or
unparking the vehicle. Hence, it is the most safest parking from the
accident perspective.
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Parking system
2. 30◦ parking: In thirty degree parking, the vehicles are parked at 30◦
with respect to the road alignment. In this case, more vehicles can be
parked compared to parallel parking. Delay caused to the traffic is also
minimum in this type of parking.
3. 45◦ parking: As the angle of parking increases, more number of
vehicles can be parked. Hence compared to parallel parking and thirty
degree parking, more number of vehicles can be accommodated in this
type of parking.
4. 60◦ parking: The vehicles are parked at 60◦ to the direction of road.
More number of vehicles can be accommodated in this parking type.
5. Right angle parking: In right angle parking or 90◦ parking, the
vehicles are parked perpendicular to the direction of the road.
Although it consumes maximum width kerb length required is very
little. In this type of parking, the vehicles need complex maneuvering
and this may cause severe accidents. This arrangement causes
obstruction to the road traffic particularly if the road width is less.
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On – street or Kerb Parking
1. Parallel Parking
2. 30 degree parking
3. 45 degree parking
4. 60 degree Parking
5. 90 degree Parking
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 Parallel Parking
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 30 degree parking
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 45 degree parking
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 60 degree Parking
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 90 degree Parking
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Parking system
Off street parking In many urban centers, some areas are exclusively
allotted for parking which will be at some distance away from the
main stream of traffic. Such a parking is referred to as off-street
parking.
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Parking survey
In-out survey
In this survey, the occupancy count in the selected parking lot is taken
at the beginning. Then the number of vehicles that enter the parking lot
for a particular time interval is counted. The number of vehicles that
leave the parking lot is also taken. The final occupancy in the parking
lot is also taken. Here the labor required is very less. Only one person
may be enough. 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. For quick survey purposes, a fixed period
sampling can also be done. 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 i hour, the count is
again taken. Here there are chances of missing the number of vehicles
that were parked for a short duration. BITS Edu
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Parking survey
License plate method of survey
This results in the most accurate and realistic data. In this case of
survey, every parking stall 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. If the time interval is shorter, then there are less chances of
missing short-term parkers. But this method is very labor intensive.
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Parking survey
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ACCIDENT STUDY
Causes of road accidents
1. Road Users - Excessive speed and rash driving, violation of traffic
rules, failure to per-ceive traffic situation or sign or signal in adequate
time, carelessness, fatigue, alcohol, sleep etc.
2. Vehicle - Defects such as failure of brakes, steering system, tyre
burst, lighting system .
3. Road Condition - Skidding road surface, pot holes, ruts.
4. Road design - Defective geometric design like inadequate sight
distance, inadequate width of shoulders, improper curve design,
improper traffic control devices and improper lighting.
5. Environmental factors -unfavorable weather conditions like mist,
snow, smoke and heavy rainfall which restrict normal visibility and
and makes driving unsafe.
6. Other causes -improper location of advertisement boards, gate of
level crossing not closed when required etc.. BITS Edu
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ACCIDENT STUDY
Collision Diagrams
Collision diagrams are used to display and identify similar accident
patterns. They provide information on the type and number of
accidents; including conditions such as time of day, day of week,
climatic conditions, pavement conditions, and other information
critical to determining the causes of safety problems.
Accident reports should be organized by year of occurrence and
accident type for the analysis period. Accidents that occurred after
significant changes in highway or local land use should not be
included.
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ACCIDENT STUDY
A. Construction of Collision Diagram
Sketch of the collision diagram for either an intersection or a roadway
section using a standard form as shown on the following page.
1. The sketch need not be to scale.
2. Show the path of each vehicle involved in the accident with
adequate room for information.
3. Place a north arrow for orientation and any other descriptive
information:
a) Location identification
b) Period of analysis
c) Label the roads
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ACCIDENT STUDY
4. Sketch the path of each vehicle to show vehicle manoeuvre, type of
collision and accident severity, and;
a) Time of day
b) Day of week
c) Date
d) Lighting condition
e) Pavement condition
f) Other important information, e.g., alcohol involvement
B. Symbols
Symbols representing the nature of operation, vehicle or object
involved and severity of the accident are adopted. These are shown in
the example collision diagram below. Symbols to represent types of
collisions diagrams are also standardized.
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ACCIDENT STUDY
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ACCIDENT STUDY
Condition Diagrams: The purpose of the Condition Diagram is to
show the intersection and the conditions within the surrounding area as
it exists. The diagram should include the intersection alignment, items
such as buildings, sidewalks, trees, lighting poles, water hydrants, stop
signs, number of lanes, and lane use if required, associated with the
streets forming the intersection. When applicable, the Condition
Diagram shall show the length of all exclusive lanes.
The Condition Diagram provides the engineer with details of field
conditions and helps investigate the need for changes to existing traffic
control devices. The diagram should also be part of an intersection
crash analysis.
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ACCIDENT STUDY
Preparing the Condition Diagram
A. General Details
1. The engineer should enter the Location I.D. so that the intersection
is thoroughly identified.
2. The name of the highway, highway number, and direction for both
streets should be included.
3. County, City, Date, and Person(s) preparing the diagram.
4. Orient the intersection by indicating north on the north arrow.
All items associated with the streets should be drawn using the
symbols as outlined on the bottom of the form.
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ACCIDENT STUDY
B. Highway and intersection design features, including:
a) Pavement edges, curbs, and shoulders (unpaved or paved)
b) Widths of approaches
c) Approach grades
d) Channelization
e) Parking conditions and restrictions
f) Bus stops
g) Safety lighting or continuous lighting
h) Any other roadway features which may affect traffic operations
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ACCIDENT STUDY
C. Roadside development, including:
a) Sight distance restrictions (trees, bushes, advertising and other
signs, poles, fences, bridge, and guard rails)
b) Off street parking
c) Driveway locations
d) Utility and other poles
e) Adjacent land use
f) Any other pertinent features
D. Traffic control devices, such as:
a) Signs
b) Traffic signals (type, face locations, etc.)
c) Distance to adjacent traffic signals within 1.61 km (one mile)
(indicate if none)
d) Pavement markings
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ACCIDENT STUDY
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PREVENTION OF ROAD
ACCIDENT
Strict punishment should be enforced
by govt. if a person drives in over
speed
Tamper proof speed controllers
should be installed in all vehicles.
Two wheelers should not exceeded
50-70km/h.
All the rules should be followed
properly by the people.

THANK
YOU
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5

Chapter 2 traffic studies

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