1. CHARACTERISTICS OF TRAFFIC ENGINEERNG

2. TRAFFIC ENGINEERING
Deals with improvement of traffic performance of Road Networks.
Application of Scientific principles and Techniques for
safe ,rapid, convenient &economic movement of people. .

3. TRAFFIC characteristics
Road User Characteristics
Vehicular Characteristics

4. Road user characteristics
Considers the aspects of human behavior on roads.
PHYSIOLOGICAL CHARACTERISTICS- Measurable and Usually Quantifiable Characteristics
Vision
Hearing
PSYCHOLOGICAL CHARACTERISTCS-
More difficult to measure and quantify
Perception
Intellection
Emotion
Volition

5. vision Most important factor that affects highway design & safety.
(a). Acute or clear vision cone-Field of clearest & acute vision is within the cone whose angle is 3° about the centre line of Retina.
Helps for Distant Vision.

6. (b)Fairly clear vision cone- Vision is satisfactory when angle of cone is 10° to 12° around the line of sight;
color and shape can be identified in this field.
Important for locating Traffic signs and signals.
(c) Peripheral Vision- Total Visual Field for two eyes.
Vision is possible but without clear details and colour.
Angle of Peripheral Vision-
160 ° in horizontal Direction
115 ° in vertical Direction.
vision

8. glare recovery
Driver’s Ability to adapt glare and variations in lighting conditions.
Factors affecting Glare recovery –Age, Wearing of eyeglasses
Recovery time : 3-6 seconds

9. colour vision Most important for identifying : - Traffic lights
-Traffic signs
Drivers feel difficulty to recognize proper signals.

10. depth perception
Ability to judge the distance and speed of approaching vehicles
Important to pedestrians to cross the road.
For Driver ,judgment of speed of other vehicles is important.

11. hearing Very vital to road user. To hear SOUND OF HORNS
Alert Pedestrians
Important to elderly people with falling eyesight

13. psychological characteristics
PIEV THEORY
PERCEPTION
INTELLECTION
EMOTION
VOLITION

14. psychological characteristics
PERCEPTION: Time required to perceive an object
INTELLECTION: Time required for understanding the situation.
EMOTION: Time elapsed during emotional sensations and disturbances.
VOLITION: Time taken for final action

15. Age of driver Problems of younger drivers
Difficulty in judging speed, distance and reaction time
Tend to concentrate on near objects
Missing the important information, because its relevance is not understood
Having difficulty in integrating information
Under-estimating the risk of accident involvement
Making less effective driving decisions

16. Age of driver Take time to absorb traffic control information
Problems of older drivers Difficulties in rapid decision making
At intersections
Take time to absorb traffic control information
Difficulty at night
Lower light level
Headlight glare
Readily fatigued

17. Vehicular
characteristics

18. Vehicular characteristics
Affect the design and Traffic performance.
Vehicular characteristics consist of
Static Characteristics
Dynamic Characteristics
Static Characteristics include dimensions, weight and
maximum turning angle.
Dynamic Characteristics include Speed, Acceleration ,
braking Characteristics and some aspects of body design.

19. static characteristics
1.VEHICLE DIMENSIONS
a). Width : Affect width of traffic lanes, shoulders & parking facilities .
b). Height: Affects the clearance of overhead structures.
Clearance under over bridges, under bridges, electric & other service lines.
Height of driver seat –provide clear vision of the road to his front & sides.
Height of headlight- affects sight distances at valley curves.

20. static characteristics
(contd..)
c). Length: Important factor in design of Horizontal alignment
Length affects
safe overtaking distance
Capacity of road
Extrawidening
minimum turning radius
Parking Facilities
Design of valley curves.

21. static characteristics
(contd..)
2). WEIGHT: Affects design of pavement thickness & gradients.
Limiting gradients are governed by weight & power of vehicles.

22. static characteristics
(contd..)
3) . POWER: Power of heaviest and loaded weights vehicle govern permissible and limiting gradients.
Power affects the speed and acceleration of vehicle.
4). MINIMUM TURNING RADIUS : Depends on length of wheel base and features of steering system
Affects design of sharp curves.

23. Dynamic characteristics
a). SPEED: it affects
Sight distances
Superelevation
Length of transition curve
Vertical curves
Width of pavement and shoulders
Design gradient
Capacity of traffic lane
Design of intersections.
Design speed controls most of the geometric features of the highway.

24. Dynamic characteristics
(contd..)
b) ACCELERATION: Governed by Vehicle transmission system, weight and horse power.
Maximum deceleration rate depends upon friction between tyres and pavement.

25. Dynamic characteristics
(contd..)
BRAKING CHARACTERISTICS: Important for safety.
Affects Safety of vehicle operation ,stopping distance and the spacing between two consecutive vehicles in a traffic steam
Interaction between tyre & road surface governs braking performance.
One of the prime causes of accidents during braking is the wheels getting locked and driver losing control of the vehicle.

26. Vehicle lighting system
Lighting system consist of
a). Headlight
To provide a main beam for the driver to see the road ahead.
To provide a dipper beam for avoiding glare to the opposing traffic.
b). Rear Lamps : Give indication to the driver about presence of a vehicle infront of him Avoid Front- to rear collision.
c). Direction Indicators : Give adequate notice of the intention of driver to turn or to stop.
Usually amber in colour.