Accident Study
The
problem of accident is a very acute in highway transportation due to
complex flow pattern of vehicular traffic, presence of mixed traffic
along with pedestrians. Traffic accident leads to loss of life and
property. Road accidents cannot be totally prevented but by suitable
traffic engineering and management the accident rate can be reduced. Causes of road accidents
The various causes of road accidents are:
• Road Users - Excessive speed and rash driving, violation of traffic rules, failure to perceive traffic situation in time, carelessness, fatigue, alcohol, etc.
• Vehicle - Defects such as failure of brakes, steering system, tyre burst.
• Road Condition - Skidding road surface, pot holes, ruts.
• Road design - Defective geometric design like inadequate sight distance, inadequate width of shoulders, improper curve design, improper traffic control.
• Unfavorable weather condition
Accident data collection
The data collection of the accidents is primarily done by the police. Motorist accident reports are secondary data
which are filed by motorists themselves. The data to be collected should comprise all of these parameters:
• General - Date, time, person involved in accident, classification of accident like fatal, 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 - Details of collision, damages, injury and casualty
• Road and traffic condition - Details of road geometry, surface characteristics
• Accident cost - Financial losses incurred due to property damage, personal injury and Casualty
Accident analysis
Site Analysis
One of the most important tasks in traffic safety is the study and analysis of site-specific accident information to identify contributing causes and develop site remediation measures that will lead to improved safety. Once location has been statistically identified as “high-accident” location, detailed information is required in two principal ways:
1. Occurrence of accident
2. Environmental and physical conditions
The best information on the occurrence of accidents is compiled by reviewing all accident reports for a given location over a specified study period. This can be done using accident record. Environmental and physical conditions are established by a through site investigation. Two primary graphical outputs are then prepared.
1. Collision diagram
2. Condition diagram
Collision diagram:A
collision diagram is a schematic representation of all accidents
occurring at a given location over a specified period. Depending upon
the accident frequency, the “specific period” usually ranges from one to
three years. Each collision is represented by a set of arrows, one for
each vehicle involved, which schematically represents the type of
accident and directions of all vehicles. Arrows are generally labeled
with codes indicating vehicle types, date and time of accident, and
weather conditions. Condition diagram
A condition diagram describes all physical and environmental conditions at the accident site. The diagram must show all geometric features of the site, the location and description of all control devices (signs, signals, markings, lighting, etc.) and all relevant features of the road side environment, such as the location of carriage ways, roadside objects, lane uses etc.
Safety measures
The ultimate goal is to develop certain improvement measures to mitigate the circumstances leading to the accidents. The measure generally includes engineering, enforcement and education. Measures for the reduction in accident rates
The various measures to decrease the accident rates may be divided into three groups:
1. Engineering
2. Enforcement “3-Es”
3. Education
Engineering measures
a. Road design: The geometric design features of the road such as sight distances, width of pavement, horizontal and vertical alignment and intersection design elements are checked and corrected if necessary. The pavement surface characteristics are checked and suitable maintenance steps taken to bring them upto the design standards.
b. Preventive maintenance of vehicle: The braking system, steering and lighting arrangements on vehicle may
be checked.
c. Before and after studies: After making the necessary improvement in design and enforcing regulation, it is
again collect and maintain the record of accidents “before and after” the introduction of preventive measures
to study their efficiency.
b) Road lighting: Lighting is particularly desirable at intersections, bridge sites and at places where there are restrictions to traffic movements.
Enforcement measures
a. Speed control: Checks on spot speed of all fast moving vehicles should be done at selected locations and timings and legal actions on those who violate the speed limits should be taken
b. Traffic control devices: Signals may be re-designed or signal system be introduce if necessary. Proper traffic control device like signs, markings or channelizing island may be installed if necessary.
c. Training an
d. Medical check: The drivers should be tested for vision and reaction time at prescribed intervals.
e. Special precautions for commercial vehicles: having attendant to help and give proper direction to drivers of heavy vehicles.
f. Observance of law and regulations: Traffic authorities should send study groups of trained personal, to different locations to check whether the traffic regulations are being followed by the road users and also to enforce the essential regulations.
Educational measures
a. Education of road users: The passengers and pedestrians should be taught the rules of the road, correct manner of crossing etc.
b. Safety drive: Imposing traffic safety week when the road users are properly directed by the help of traffic police and transport staff is a common means of training the public these days.
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