Traffic engineering

Road User Characteristics, Vehicle Characteristics, PIEV Theory, Traffic Studies, Volume Studies,Speed Studies, Origin Destination Studies, Accident Studies,

1. Traffic engineering TE/BE/2016-2017 Part II

2. Traffic Characteristics Road user characteristics Vehicular characteristics Traffic studies Name of various studies & Uses Accident studies objectives, causes, diagrams, preventive measures Traffic regulations & Control Devices Signs, signals, markings, islands, intersections Parking facilities

3. PIEV Theory Perception Time : Time required to perceive an object Intellection Time : Time required for the driver to understand the situation Emotion Time : Time elapsed during emotional sensations. Eg . Fear,anger,shocking etc Volition Time : Time taken by the driver for the final action. Eg . Braking Total Reaction Time >> 0.5 sec to 3 or 4 sec Say it as 2.5 sec on an average

4. Vehicle Dimensions Length & Width of vehicle Width of traffic lane Shoulders, Parking facilities Capacity of roads Design of vertical & horizontal alignment Extra width of pavement Safe overtaking distance Height of vehicle Clearance to be provided under structures such as bridges, underpasses, electric lines etc

5. Maximum Dimension Of Road Vehicles Dimensions of vehicles Details Maximum dimensions ( Excluding front & rear Bumpers), m Width All Vehicles 2.50 Height Single deck vehicle for normal application 3.80 Double deck vehicle 4.75 Length Single unit truck with two or more axles ( type 2,3) 11.00 Single unit bus with two or more axles (t ype 2,3) 12.00 Semi trailer tractor combination ( Type 2-S1,2-S2,3-S1,3-S2) 16.00 Tractor & Trailer combination ( Type 2-2,Type 3-2,2-3,3-3) 18.00

6. Weight of loaded vehicle Affects – design of pavement thickness & Gradient IRC recommends maximum permissible gross weight & axle weights Power of vehicle Governs the limiting values of gradient on roads Consider : total resistance to traction, rolling resistance, air & grade resistance From total hauling capacity >>> speed & acceleration of vehicles are determined

7. Speed of vehicles Affects design of sight distance Superelevation Length of transition curves Design gradients Capacity of traffic lane Design of Control measures Braking Characteristics & Efficiency Deceleration and braking characteristics Safety of operation, sight distance, spacing Braking efficiency to be 100 % Braking system

8. TRAFFIC STUDIES Traffic volume Spot speed Speed & Delay Origin & Destination Parking Accident

9. Traffic Volume Studies Measure to quantify traffic flow No. of vehicles passing across a given traverse line of the road during unit time Expressed as no. of vehicles/hour or per day Classified traffic volume : Volume of each vehicle class separately Level of measurements of traffic volume Hourly flow ( Veh /hour) Annual Average Daily Traffic ( AADT) ( Veh /day) Average Annual Flow ( Veh /year)

10. Methods for traffic counts ( Traffic Volume ) Manual Method No. of observers needed Equipments needed Watch, Pencil, Eraser, Sharpner , Data Sheets, Clip Board Field summary sheets Automatic Method ( Devices) Sensors Pneumatic Tubes, Electric Contact, Coaxial Cables Photoelectric devices, Radar, Infrared/ Ultrasonic devices Magnetic devices Recording Mechanism Video/Photographic Method

11. Traffic volume count ( Manual)

12. Traffic volume count ( Automatic)

13. Traffic Speed Studies Change in speed of vehicles Change in Level Of Service (LOS) of the roads Spot Speed Studies: Instantaneous speed of a vehicle at specific location Method of measuring : time taken to cover a known distance Long – base Method Short – base Method

14. Radar Speed meter Photographic Method Data presented as cumulative speed distribution diagram

15. Speed & Delay Studies Running speed, fluctuations in speeds, Overall travel speed Location, duration & frequency of delays Measuring Methods: Floating car License plate / vehicle registration number Interview technique Elevated observations Photographic

16. O – D Studies Basic data for determining “ Desired Lines” Establish preferential routes for different trips Methods of conducting : Road – side interview License plate Return – post card Tag on car Home – interview method Work spot interview method Presentation of data Showing no. of trips between different zones Desire lines are plotted connecting Origin & Destination

17. ACCIDENT STUDIES Objectives To Study the causes of accidents and to suggest corrective treatments at potential locations To evaluate existing design, regulations and control measures To carryout before and after studies after implementing changes To make computations of financial loss due to accidents To provide economic justifications for the improvement measures suggested by engineers

18. Causes of accidents Drivers Excess speed, Rash driving, Violation of rules,Failure to understand the situation,fatigue,alcohol Pedestrians Violating regulations,carelessness Passengers While alighting from or getting into vehicles Vehicle defects Failure of brakes, Steering,Lighting Systems,Tyre defects Road conditions Slippery/Skidding surface, pot holes, Ruts, Obstructions to sight

19. Road design Defective geometric design, Inadequate sight distance & width Traffic Conditions Vehicles moving ahead, Presence of disable vehicles Weather Like mist, Fog, Snow, Dust, Heavy Rain Animals Stray animals on the road

20. Collision Diagram Drawn not to scale Depict the details of the accident location shows appropriate path of the vehicles and pedestrians involved in accident Shows other objects with which the vehicles have collided Most useful for Before and After studies

21. Condition Diagram Drawn to Scale Shows all important physical features of the road and adjoining area Important details to be shown are Width of roadway shoulders,medians,curves,kerb lines, Roadway conditions, Obstructions if any Both Collision & Condition diagrams can be combined together

22. Accident Reduction Measures