Accident study and analysis, objective, causes of accidents, and analysis of accident (collection of data and preparing reports and record) , types of accidents, and statistical analysis of accidents.

1. SUB: ACCIDENTA STUDY AND ANALYSIS
PRESENTED BY
RAVINDRA C

2. ACCIDENT:
Collision involving at least one moving
transportation vehicle and other
vehicle/object.

3. OBJECTIVES OF ACCIDENT STUDIES
1. To study the causes of accidents and suggest
corrective measures.
2. To evaluate existing design, regulation and
control measures.
3. To compute the financial losses incurred
4. To support the proposed design
5.To provide economic justification (road user cost,
maintenance cost and accident cost) to the
improvement suggested by the traffic engineer
5. To carry out before and after studies after
implementing changes.
6. To calculate financial losses.

4. Causes of road accidents:
1. Road users: driver, pedestrian and passenger
Driver: age of driver, fatigue, over speed, rash
driving, carelessness, violation of rules and
regulation, failure in understanding situation,
consumption of alcohol.
Pedestrian: carelessness and lack of awareness.
Passenger: boarding and DE boarding of moving
vehicles.

5. 2. vehicle:
Braking system: interaction between system
tyre and road surface governs braking
performance(skidding).failure of this causes
the accident.
Vehicle lighting system:
Main beam: enables the driver to see road
ahead for long distance.
Dipper light: provides sufficient visibility to
driver by avoiding glare to opposite vehicles
Rear lamp: gives indication of presence of
vehicle for the following vehicles.

6. Direction indicator: notice about turning
movement.
Vehicle body and its features: shape and
dimension of driver seat.
Positioning of controls wrt drivers seat.
Visibility of driver from the seat.
Noise level in the vehicle.
Screen wipers , mirrors and tyres.
Vehicle inspection and maintenance:
defects and regular servicing.

7. 3. Road and its condition:
Slipperiness: friction between the tyre and
surface.
Potholes: depressions on roads.
Sight distance: stopping sight distance and
overtaking sight distance.
Super elevation: adequate super elevation
should be provided, deficiency leads to
accidents.
Carriageway width: sufficient depending on
traffic.

8. Deficiency in road signs and markings:
Design (placing and height) of sign boards ,
stop line marking, pedestrian crossing
markings etc..
Junction design: turning radius, width of
entry and exit.
Narrow bridges and culverts: cause
serious accident when road is wide than that
of width of bridge or culvert.
Median: prevents head on collision.
Street lighting:

9. 4. Environmental factors and
weather condition:
Smoke, dust, snow, heavy rainfall.
Animals and other factors.

10. ACCIDENT ANALYSIS
 Collection of Accident Data
 Accident Report
 Accident Records

11. COLLECTION OF ACCIDENT DATA
General - Date, time, person involved in accident,
classification of accident like serious, minor
• Location - Description and detail of location of
accident
• Details of vehicle involved - Registration number,
description of vehicle, loading detail, vehicular
defects
• Nature of accident – pedestrians or object involved,
Details of collision, damages, injury.

12.  Road and traffic condition - Details of road
geometry, surface characteristics, type of traffic,
traffic density etc..
 Primary causes of accident - Details of
various possible cases (already mentioned)
which are the main causes of accident.
 Accident cost - Financial losses incurred due to
property damage, personal injury and computed
in terms of rupees

13. ACCIDENT REPORT
 Accident should be reported to police
authorities.
 Accident report is useful in subsequent
analysis, claim for compensation , evaluation
of cost, etc…

14. ACCIDENT RECORDS
 Location Files
useful to keep a check on the location of
accidents and to identify points of high
accident insedence.
 Spot Maps
spot map show accident by spots, pins or
symbol on road map.

15.  Condition Diagrams
 It is the diagram showing all the physical
conditions of an accident location to be
studied.
 features generally to be shown in diagram
are roadway limit, kerb lines, curves,
bridges, culvert, sign signals, obstruction
to vision etc by using symbols

16. CONDITION DIAGRAM

17.  Collision Diagrams
 This diagram shows the approximate path
of vehicles and pedestrians involved in the
accidents.
 this diagram is useful to compare the
accident pattern before and after the
remedial measures have been taken.

18. COLLISION DIAGRAM

19. ACCIDENT INVESTIGATION & STUDIES
 Accident investigation
 Analysis of Individual Accidents
 Statistical Analysis of Accidents

20. ACCIDENT INVESTIGATION
 Recording general observations: partially or full break
application collision and condition diagram,
environmental condition , pavement surface condition
 Driver Tests: alcohol content, vision, reaction time, age,
distance judgment.
 Skid Resistance of Pavement Surface: skid distance
,skid resistance, speed of the vehicle
 Vehicle Tests: age of vehicle, indicators, type, type of
tyres, mirrors, brakes, steering
 Probable causes of the accidents: type of accident,
Position of vehicle and object involved in accidents.
 Cost Analysis

21. ANALYSIS OF INDIVIDUAL ACCIDENTS
Each Road accident is to be analysed by the
traffic engineer to draw sound conclusions with
reference to the major cause of accident and
other contributing causes . A few simple type of
vehicular accidents are :
1. A moving vehicle collide with the stationary
object
2.A moving vehicle collide with a movable object
.
3. To vehicles approaching from different
directions collide at an intersections.
4.Rear end collision of two moving vehicles .

22. STATISTICAL ANALYSIS OF ACCIDENTS
 The statistical analysis of road accidents
help to asses the effectiveness of various
measures to decrease the accident rate .
 The accident rate may be expressed as
no. of accidents in a year.
 Accident prone stretches of different roads
may be assessed by finding the accident
density per unit length of the road.

23. STATISTICAL ANALYSIS OF ACCIDENTS
METHODS
1. Regression Analysis
2. Poisson’s distribution
3. Use of chi-squared test
4. Quality control methods

24. MEASURES FOR REDUCTION IN ACCIDENT RATE
 Engineering
 Enforcement
 Education

25. ENGINEERING MEASURES
 Road Design
 Preventive measures of vehicles
 before and after studies
 road lighting

26. ENFORCEMENT
 Speed control
 Traffic control devices
 Training and supervision
 Medical check
 Special precaution for commercial vehicles
 observance of law and regulation

27. EDUCATION
 Education to road users
 Safety drive

28. LEVEL OF SERVICE
LOS measures how well traffic moves along a
roadway. It is the term used to qualitatively
describe the operating condition of roadway
based on factors such as speed, delay, travel
time, and safety.
It is designated with letter A to F where A
representing the best and F representing
worst.

29. FACTORS AFFECTING LOS
 Speed and travel time
 Traffic interruptions/ Restrictions
 Freedom to travel with desired operating
speed
 Driver comfort and convenience
 Economy, Operating cost

30. VARIOUS LOS
 LOS A : Traffic volume is less hence free
flow of traffic is available. Drivers can select
the desired speed. Merging, diverging, lane
changing movements can be easily done
even at maximum density the average
spacing between vehicle is 167 m.
 LOS B: Zone of reasonably free flow. Free
flow speeds are still maintained while
drivers freedom to chose desired speed is
slightly restricted. The lowest average
spacing between vehicles is about 100m.

31.  LOS C: Presence of other vehicles began to
restrict the manoeuvrability within the traffic
stream. Average speeds remain near the free
flow but significant increase on driver
vigilance is required at this level. Min average
spacing between vehicles is 67 m. Queues
formed behind is sign of blockage.
 LOS D: Avg speed began to decline with
increase in flow. Freedom of manoeuvre
within traffic stream is restricted. Spacing
between vehicle is 50m as stream as little
space, minor incidents can lead to queuing of
vehicles.

32.  LOS E : At this level stream reaches its
maximum density level. There will be no
usable gaps on streams and even slight
disruption will cause a breakdown with
queues forming rapidly behind disruptions.
Moving within stream is extremely different.
 LOS F: This describes condition on a queue
that has formed behind a point of
breakdown or disruption. LOS F represents
the region of forced flow, having low speed
and complete breakdown of system.

33. THE END