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.
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.
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
16. WARNING SIGNS
To indicate Cross roads, School Zones, Narrow
Bridges, Steep Hill etc.
17.
18. Informatory Sign
Signs are used to guide the road users
along routes, inform them of destination,
distance and provide with information.
19.
20.
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
23.
24. ADVANTAGES OF TRAFFIC SIGNALS
To reduce accidents
To facilitate orderly movement of traffic
More economical
To provide safe and orderly movement of vehicles
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
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.
37.
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