Traffic engineering involves the planning and design of roads and intersections to optimize traffic flow. Key aspects include conducting traffic studies to determine volume and patterns, installing traffic control devices like signs and signals, designing intersections, and separating road grades. Traffic signs help regulate, warn, and guide drivers while markings delineate lanes and spaces. Intersections come in various forms like squares, Ts, and Ys, with squares and roundabouts being safer options. Grade separations allow roads to cross without intersecting to reduce conflicts. Accident prevention requires both engineering solutions and enforcement of traffic rules.

1. TRAFFIC ENGINEERING

2. TRAFFIC ENGINEERING
Introduction
Traffic Volume Study (TVS)
Traffic Control Devices
Grade Intersections
Grade Separations
Road Accident

3. INTRODUCTION
 A branch of civil engineering concerned with
the Design and Construction of streets and
roads under Traffic operation
 Phase of Highway Engineering which deals with
the
Planning & Geometric Design of Highway
 Includes the Analysis to Traffic characteristics,
Planning, Designing & Control of Control
devices.

4. TRAFFIC VOLUME STUDY
• Traffic volume is the no of vehicles crossing a section
of a road per unit time.
The uses of traffic studies are as follows:-
• Planning
• Traffic operation and control
• Traffic pattern
• Structural design of pavement
• Design and extension of existence road

5. METHODS OF TRAFFIC VOLUME STUDY
 Manual counting
 Automatic counters
 Moving car method
MANUAL COUNTING
A field team of traffic persons are deputed to record traffic
volume on the prescribed record sheets in specified period.
ADVANTAGES
The field team can record the type and direction of vehicles.
DISADVANTAGES
It is not practicable to do manual counting for all the 24 hours
of the day.

6. AUTOMATIC COUNTERS
 The total number of vehicles crossing at a road intersection
in the desired period is automatically recorded by a
mechanical recorder (photo electric cell, electric circuit)
ADVANTAGES
The automatic recorders is that they can work throughout the
day
DISADVANTAGES
The automatic recorders cannot record
the type and direction of vehicles

7. Passenger Car Unit
(PCU)
 It is a vehicle unit used for expressing highway
capacity.
 One car is considered as a single unit, cycle,
motorcycle is considered as half car unit.
 Bus, truck causes a lot of inconvenience
because of its large size and is considered
equivalent to 3 cars or 3 PCU

8. Type of Vehicle PCU
 Car, taxi, pick up 1.0
 Cycle, motor cycle 0.5
 Bus, truck, 3.0 (4.o in some cases)
 Horse drawn cart 4.
 Bullock cart 6.0
 Bullock cart (Large) 8.0

9. Traffic Density
 Traffic density is the number of vehicles occupying
a given length of the highway in a traffic lane.
 It is expressed as vehicle/mile or
vehicle/kilometer.

10. TRAFFIC CAPACITY STUDY
 It is the ability of the road to accommodate traffic
under operating conditions.
TRAFFIC FLOW CHARACTERISTIC STUDY
This study is useful for Geometric design features like
Traffic capacity, Volume, No of lanes, Width of carriage
way .
ORIGIN AND DESTINATION STUDY
It was undertaken to measure Travel characteristics like
no of vehicles, their origin and destination in each zone
PARKING STUDY
A data collection related to space available for vehicles
and types of vehicles demand for parking.

11. Traffic Control Devices
 Rod signs
 Road Marking
 Road signals
 Traffic Island

12. TRAFFIC SIGNS
 These are used to Control and guide the traffic
 To prevent accident
 Should be provide only where necessary
TYPES OF TRAFFIC SIGNS
 Regulatory Sign /Mandatory Signs
 Warning Sign /Cautionary Sign
 Informatory Sign /Guiding Sign

13. Regulatory / MANDATORY SIGNS
 Prohibitory Sign
 Stop and Give way sign
 Speed Limit Sign
 Compulsory Direction
Sign
 Restriction End Sign

14. PROHIBITORY SIGNS
 Playing horns near hospitals
 Overtaking and parking at certain places

16. WARNING SIGNS
 To indicate Cross roads, School Zones, Narrow
Bridges, Steep Hill etc.

18. Informatory Sign
Signs are used to guide the road users
along routes, inform them of destination,
distance and provide with information.

21. PURPOSE OF TRAFFIC SIGNS
 Reduce the traffic accident
 To control the speed on the main and cross roads
 To provide orderly movement of vehicles
 Traffic quality should be improved

22. TRAFFIC SIGNALS
 Traffic signals are provided at road intersections
 To control, warn and guide the traffic
 Red – Top – Stop
 Yellow (or) Amber – middle – Slow
 Green – Bottom – Go

24. ADVANTAGES OF TRAFFIC SIGNALS
 To reduce accidents
 To facilitate orderly movement of traffic
 More economical
 To provide safe and orderly movement of vehicles

25. Road marking
PAVEMENT
MARKING
KERB
MARKING
OBJECT
MARKING
OBJECT
MARKING

26. Pavement Marking
1.Centerline
2.Lane Line
3.No Passing Zone
4.Stop Line
5.Cross Walk Line
6.Parking Space Limit
7.Pavement Space Lines
8. Pavement Edge Lines

31. SQUARE JUNTIONS
 Two roads cross each other at right angle
TYPES
 All paved type
 Separate turning lane type
 Circular turning lane type
 Elliptical round – about type
 Turbine type

32. GRADE INTERSECTIONS
These are road crossings, where the road cross each other at
the same level.
TYPES OF GRADE INTERSECTIONS / ROAD JUNCTIONS
Square junction
Acute junctions
T-junctions
Y- junctions
Staggered junctions
Multiple junctions

34. TYPES OF SQUARE JUNCTION

36. PREVENTION OF ACCIDENT
 Engineering Aids
 To provide Traffic Signals
 Improving Street lights
 Construction grade separations
 Providing proper cross section of road
 Providing non skid and uniform surface
 Enforcement Aids
It is the duty of traffic police to guide and force the traffic
to obey the rules of the road.
 Educational Aids
The road users should realise the large difference in speed
between pedestrians and vehicular traffic.

38. ACUTE JUNCTIONS
Two roads cross each other at an angle other than
a right angle.
Also called as skew junctions
It do not provide the sufficient sight distance.
TYPES
All paved Type
Island Type
Slip round Type

39. GRADE SEPARATIONS
 Road junction at which the two roads / a road / a
railway line cross each other at different levels.
 Also know as Fly-overs.
TYPES OF GRADE SEPARATIONS
 Over and Under- Crossing
 Diamond – Crossing
 Clover leaf Pattern
 T-pattern (Trumpet)

40. T-JUNCTIONS
 Two roads join at right angle (form T-shape)
TYPES
 All Paved Type
 Triangular Island Type
 Elliptical Island Type

41. Y- JUNCTIONS
 Two roads join and do not cross at an angle other
than a right angle.(Y Shape)
 These junctions are dangerous.

42. TYPES OF Y- JUNCTION
 All Paved Type
 Triangular Island Type
 Circular Island Type
 Channelized ‘Y’

43. STAGGERRED JUNCTIONS
 In this type , the branch roads meet the main road at right
angles at a good distance.
 These are very dangerous.
 Proper warning signals should be provided
Branch road Main road

44. MULTIPLE JUNCTIONS
 More than two branch road meets the main road at
an angle other than right angle.
 Highly dangerous.
 Special precautions should be provided.

45. ROAD ACCIDENT
 A collision of a highway user with another highway user/
highway property resulting in death, injury or property
damage.
CAUSES
 Physical defects of the road user
and vehicles.
 Adverse weather condition.
 Insufficient sight distance.
 Insufficient pavement width
 Carelessness and lethargy of
road user

48. Thank you
Prepared by,
Prof. P.G.Shinde