Road safety

1. MODULE 5

2. Syllabus
Road Safety Situation in India, Causes of road
accidents – influence of road, vehicle, driver and
environmental factors - Pedestrian Safety,
Collection and statistical analysis of accident
data, Collision and condition diagram,

3. Road Accidents
• An event that occurs on a street open to public traffic;
resulting in one or more persons being injured or killed,
where at least one moving vehicle is involved.
• Road Traffic Accident is a collision between vehicles;
between vehicles and pedestrians; between vehicles and
animals; or between vehicles and geographical or
architectural obstacles.

4. Collection of accident data
• Serves to identify the basic causes of accidents
and suggest means for overcoming the
deficiencies that lead to such accidents
• Engineering uses
• Enforcement uses
• Administrative and policy uses
• Educational uses
• Uses for the motor vehicle administrator

5. Engineering Uses
• In determining the adequacy, size, shape and
legibility of traffic signs
• In determining the justification for traffic control
devices, such as traffic signals
• In determining and planning pedestrian safety
features (underpass, overbridges, barriers, refuge
islands, signals, street lighting)
• In determining speed zoning and speed control
• In planning traffic regulation measures
• In designing and providing channelization

6. Enforcement Uses
• In planning deployment of personnel for duties such
as manual control, streel patrolling etc.
• In controlling pedestrian behaviour
• In directing enforcement effort
• In enforcing curb parking regulations
• In planning and enforcing vehicle inspection
measures
• In aiding prosecution of offenders in courts

7. Administrative and policy uses
• In initiating and administering traffic safety
programmes
• In evaluating success of traffic safety programmes
• In determining the accident costs
• In identifying the need to amend the legislative
measures in force and to take appropriate action to
amend them

8. Educational Uses
• In planning and organizing school safety
education programmes
• In planning and organizing driver safety
educational programmes

9. Uses for the motor vehicle administrator
• In reviewing the procedures for licencing drivers
• In reviewing the procedures for registration and
licencing of vehicles
• In reviewing the vehicle inspection requirement

10. Requirements of accident records
• If accident records are to be of use, they should be accurate
and comprehensive, instead of being vague and misleading
• Must be reported on a standard form so that uniform
procedure is followed
• The term describing the accidents (fatal accident,
grievously injured person, slightly injured person, minor
injury accidents etc.) must be accurately defined.
• For the facility of being analysed by a computer, the data
should be coded properly.

11. Standard accident reporting forms
• Forms prescribed by IRC 1982
• Form A-1: Form for collecting the details of
the accident
• Form 4 : Summary of the road accidents in the
State during the year

12. Factors Causing Road Accidents
• The road
• The vehicle
• The driver
• The road user other than the motorists
• Environmental factors

13. The Road
• Radius of Curvature
• Vertical Alignment
• Sight distance
• Super elevation
• Carriageway width
• Width and condition of shoulder
• Road signs and road markings
• Junction design
• Pavement surface characteristics
• Formation delineators and guard rails
• Narrow bridges and culverts
• Median width
• Street lighting

14. Radius of Curvature (RoC)
• Safe speed while negotiating a curve depends on RoC
• Sharpe curves- low speed
• Large radii curves – high speeds
• Provide RoC as large as possible

15. Vertical Alignment
• Provide suitable shock proof vertical curves
• Vertical curve should homogeneously blend in with the
horizontal curve

16. Sight Distance
• Safe stopping and overtaking sight distance
• All roads should be designed for safe stopping sight
distance and overtaking sight distance
• If overtaking is prohibited – provide suitable signs

17. Super elevation
• For vehicle negotiating a curve at the desired
speed – adequate super elevation should be
provided.
• Deficiency cause accidents

18. Carriageway Width
• Minimum width – 7 m for 2 lanes
• Most of Indian roads are single lane
• Danger due to overtaking and crossing
• Intermediate lane width of 5.5 m for roads where
the traffic is heavy for single lane

19. Width and conditions of shoulder
• Shoulders needed for parking stopped vehicles are
used for overtaking and crossing vehicles.
• Shoulders should be of adequate width
• Should be maintained properly even during rainy
season

20. Road Signs and Road Markings
• Properly and well maintained road signs – prevent
accidents
• Centreline marking, stop line marking, pedestrian
crossing marking can reduce accidents.

21. Junction Design
• Any deficiency in the design of junctions cause accidents
• Elements of junction design should receive proper
attention
– Turning radius
– Width at entry and exit
• Channelization reduce no. of collision points, thus
reduce accidents

22. Pavement Surface Characteristics
• Pavement Surface Characteristics determine the
safety of a vehicle when applying brakes and
negotiate a curve
• Road surface should have anti-skid properties
when the pavement is wet

23. Formation delineators and guard rails
• On curves or embankments driver needs to be guided
about the direction of the road- Formation delineators
with reflection are provided
• Guard rails and safety barriers prevent the vehicle from
going off the roadway

24. Narrow bridges and culverts
• Narrow bridges and culverts cause accidents,
especially if the roadway is wide.
• If accidents occur frequently – widen it
• Proper warning signs prevent accidents

25. Median Width
• Wide median prevents glare from opposite stream of
vehicles
• 5 m is desirable width
• Extreme situations (less space) – 1.2 m width

26. Street lighting
• Adequate street lighting during night time
prevent accidents
• Also reduces the more severe type of accidents

27. The Vehicle
• Braking system
• Vehicle Lighting system
• Vehicle body and its features
• Tyres
• Vehicle inspection and maintenance

28. Braking System
• Interaction between tyre and roads governs the braking
performance of vehicles
• Element of design of braking system involve:
– Load distribution among different wheels
– Brake distribution between the front and rear wheels
• Prime cause for accidents – wheels getting locked and the
driver losing the control of vehicle
• Research undertaken –ways of applying the brakes
severely but at the same time to prevent the vehicles from
being locked.

29. Vehicle Lighting System
• Efficiency and reliable system of lighting in vehicle
prevent accidents
• Lighting system consists of
– Headlights – glare is a serious problem
– Side lamps
– Parking lights
– Rear lights – efficient operation prevent front to rear
collision
– Direction indicators
– Stop lamp

30. Vehicle Lighting System
• Head light should perform 2 functions:
– Main beam: allows driver to see road ahead for long
distance
– Dipper beam: avoids glare to opposing traffic, at the
same time provides sufficient visibility
• Direction indicators provide adequate notice of
the intention of driver to turn or to stop.
– Usually amber in colour
– Provided at side of vehicle at the eye level of driver of
the following vehicle

32. Vehicle body-its features
• Factors to be considered
– Shape and dimension of driver seat
– Position of control in relation to driver seat
– Visibility of the driver from the seat
– Noise levels in the vehicle
– Concentration of carbon monoxide inside the vehicle

33. Vehicle body-its features
• Seat of the driver should be comfortable and adjusted
to give him a clear view
• Dials must be clearly visible and controls must be easily
operated
• For better design: the lack of proper vision due to
bonnet and windscreen pillars should be minimum.
• External mirrors fitted on the sides provide better
visibility to the rear portion.

34. Tyres
• Important aspect of vehicle design
• Research works done about:
– Performance of tyre relative to puncture, blow-outs,
vulnerability to damage by sharp objects, braking and road
surface characteristics
• Skidding is governed by the interaction of the tyre,
brakes, road surface, speed and wetness of the road
surface

35. Vehicle Inspection and Maintenance
• Frequent inspection and testing is an important
requirement
• In India, old vehicles used to their maximum life time
• Period inspection of
– Brakes, tyres, lighting system
– Steering mechanism, suspension system,
– windscreen
• Legislative enforcement of inspection system yield
good results in safety.
– UK and USA compulsory
– India, as per Motor Vehicle Act – period testing and
inspection of vehicles

36. The Driver
• Driver judgement, skill and emotional make up
• Age and sex of drivers
• Marital status
• Training of drivers
• Alcohol, drugs and the driver
• Fatigue
• Use of helmets and safety belts

37. Driver judgement, skill and emotional make up
• The time taken to perceive the danger depends upon his
mental makeup- perception time
• Once the information gone to his mind, some time must
elapse before he react to the stimulus – reaction time
• PT and RT vary from driver to driver (total = 2.5 s)
• PIEV time – perception, intellection, emotion and volition
• How driver react to situations? – based on past experience,
driver education and his estimate of his own capacity
• Skill – driver’s capacity to control and manipulate
– Partly inborn
– Training and experience

38. Driver judgement, skill and emotional make up
PIEV time – perception, intellection, emotion and volition
Perception time : Is the time required for the sensations received
for the eyes or ears to be transmitted to the brain through
nervous system and spinal cord. Time required to perceive an
object or situation
Intellection time: time required for understanding the situation.
Emotion time: time elapsed during emotional sensations and
disturbance such as fear, anger etc.
Volition time: time taken for the final action.

39. Age and Gender of driver
• Young drivers cause more accidents rather than mature
drivers
• Old drivers cause more accidents than middle age
drivers
• Males have more accident records than female, but
when miles driven are taken into account the difference
disappears.
• Married drivers have been observed to better drivers
(both male and female)

40. Training of Drivers
• Systematic training of drivers have impact on driving
behaviour and performance
• Truck and bus drivers receive classroom training and
driving instructions
• Suitable legislation – driving instruction should be given
by fully qualified personnel

41. Training of Drivers contd...
• Reward for good and clean driving should be provided.
• Penalties for negligent drivers.
• Those who have licenses have learnt the basic principles
of driving and traffic rules
• Those who accure licence should be able to handle their
vehicle.

42. Alcohol, drugs and the driver
• Alcohol and drug affect the judgement and skill of a driver
• Traffic on roads at midnight is less but accidents are more
-reason is alcohol
• Alcohol enters into the blood stream after it is consumed
( measured by simple clinical test)
• The actual amount of alcohol in blood depend on: amount
consumed, weight of that person, kind of alcohol, time
interval between alcohol and test etc.
• If blood alcohol content is > 50 mg/100 ml, the driver is
unfit to drive

43. Alcohol, drugs and the driver
• Different countries, the limitations are different
• In India, Motor Vehicle act provides suitable punishment
for drivers under the influence of alcohol and drugs
• India Road Congress – blood alcohol content of more
than 0.08% should be liable for fine or imprisonment
(3 months)

45. Fatigue
• Long hours of driving – lack of concentration
• Long and monotonously straight sections of a road –
induce drowsiness and lack of vigilance
• Alignment with good blend of straight and curvature
tend to keep the driver alert
• Loss of sleep causes drowsiness and lapses in attention
• Limiting the period of driving by regulations – to prevent
accidents in case of professional drivers

46. Use of helmets and safety belts
• Motorcycles and pillion riders – prone to head injuries
• Protecting head against injuries – reduce fatalities
• Wearing helmet reduces 30-40% of head injuries
• IRC suggest to make helmets compulsory and those who
not wear helmets are to be fined
• If a driver does not wear a seat belt and if any accident
happens – diver thrown out of the vehicle
• Safety belts can save many lives – strong enough to bear
the forces that will act on him/her
• Automatically inflatable air bags reduce the driver
fatalities considerably.

48. Lack of Monitoring Agencies
Increase in road accidents due to:
• Non-cooperation from road related authorities
• Authorities allow movement of
– non-road worthy vehicles
– Movement of extra length vehicles
– Abnormally loaded
– over projected goods loaded vehicle

49. Weather and its effects on accidents
Elements of weather that cause accidents are:
• Rain:
– causes the pavements to be slippery, contributes to
skidding accidents.
– Higher the rainfall, higher the accidents rate
• Snow and ice:
– accidents more frequent
– Slipperiness is the major cause
• Fog:
– visibility get reduced just a few meters under the
thick fog

50. Condition and Collision Diagrams
Collision Diagram
• Schematic Representation of all accidents occurring
at a given location over a specified Period usually
ranges from one to three years
• Diagram contains a large scale map of the location
and the paths of the vehicles and position of the
pedestrians involved in each of the accidents
• A uniform system of symbols would be necessary to
identify the full details and nature of the accidents

53. Condition Diagram
• The purpose of the Condition Diagram is to show
the intersection and the conditions within the
surrounding area as it exists.
• The diagram should include the intersection
alignment, items such as buildings, sidewalks, trees,
lighting poles, water hydrants, stop signs, number
of lanes, and lane use if required, associated with
the streets forming the intersection.
• When applicable, the Condition Diagram shall show
the length of all exclusive lanes and associated
tapers.

55. • The Condition Diagram provides the engineer
with details of field conditions and helps
investigate the need for changes to existing
traffic control devices. The diagram should
also be part of an intersection crash analysis.

56. Preparing the Condition Diagram
A. General Details
1. The engineer should enter the Location I.D. so that the intersection
is thoroughly identified.
2. The name of the highway, highway number, and direction for both
streets should be included.
3. County, City, Date, and Person(s) preparing the diagram.
4. Orient the intersection by indicating north on the north arrow.
All items associated with the streets should be drawn using the
symbols as outlined on the bottom of the form.
The diagram should also include B.
Highway and intersection design features, including: a) Pavement
edges, curbs, and shoulders (unpaved or paved) b) Widths of
approaches c) Approach grades d) Channelization e) Parking conditions
and restrictions f) Bus stops g) Safety lighting or continuous lighting h)
Any other roadway features which may affect traffic operations