Traffic studies for planning bypasses around towns A bypass is a road or highway that avoids or "bypasses" a built-up area, town, or village, to let through traffic flow without interference from local traffic, to reduce congestion in the built-up area, and to improve road safety.

1. TRAFFIC STUDIES
FOR
PLANNING BYPASSES
AROUND TOWNS
BY
KIRAN CHAPPA
2013BPLN028

2. INTRODUCTION
• A bypass is a road or highway that avoids or "bypasses" a built-up
area, town, or village, to let through traffic flow without
interference from local traffic, to reduce congestion in the built-up
area, and to improve road safety.
• Particulars such as volume,origin,destination and
delays,Pertaining to through and local traffic are required for
justifying the Provision of a bypass.

3. • Depending Upon its Origin and destination, the traffic going through a
town can be classified as:
I. External to External :Traffic whose Origin and destination both lie
outside the town. It is totally Bypassable whereas others traffic is not.
I. External to Internal :Origin of traffic outside and destination inside the
town.
II. Internal to External : Origin of traffic inside and destination outside the
town.
III. Internal :Traffic whose origin and destination both lie
within the town

4. ORIGIN AND DESTINATION SURVEY
• Selection of survey Points
Survey stations should be located where the approach roads intersect
the cordon line drawn to enclose the town under study.
I. The cordon line should be well away from the town for effectively
identifying the bypassable traffic.
II. The cordon line should encompass all existing bypasses catering to
regional traffic moving around the town.
• The surveys should normally be conducted for seven consecutive days
but in any case for not less than three days and must encompass the
weekly market and one working day.

5. METHODOLOGY
Depending upon the size of the town,
the survey can be carried out by any of
the following methods:
1. Registration plate method
2. Tag and disc method
3. Roadside interview method

6. Registration Plate method :
• Registration number of vehicles and time of entry and exit of the
inbound and outbound vehicles are noted down at each survey point.
• This method does not cause any inconvenience to traffic.
• It is suitable for very small towns
Tag and disc method :
• The vehicles entering the town stopped at survey points and tags with
entries such as the time of entry, place of entry and type of vehicles
are tied to the front of the vehicles. Sometimes Discs are distributed
to the drivers.
• When the vehicles leave the town at the cordons, these tags of discs
are collected by the surveyors.

7. Road side interview method :
• Inbound vehicles are stopped at the survey points and information on
time of interview, type of vehicle, registration number etc., are noted
down by the observer.
• Then the observer puts questions to the driver to get information on
origin, destination, purpose of trip and purpose of halts within the
town etc.
TRAVEL TIME AND DELAY STUDIES
• This study can be conducted by the moving car technique. By this
technique, a test vehicle is run at the perceptible average speed of
the traffic stream.

8. • The survey can be conducted by any one of the following methods:
1. Floating car method : In this method, the driver has to overtake an
equal number of vehicles which over take the test car.
2. Average car method :In this method, the driver runs the test vehicle
at the average speed which he considers as the average speed of the
traffic stream.
3. Restricted car method : this method is the same as average car
method. But it overcomes the disadvantage existing in the latter by
restricting the speed of the test vehicle under speed flow conditions
to predetermined speed limits.

9. THANK YOU