Module 8 : Specialized Traffic Studies
Lecture 42 : Accident Studies
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Accident Analysis

Accident data collection

The accident data collection is the first step in the accident study. 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:
  1. General - Date, time, person involved in accident, classification of accident like fatal, serious, minor
  2. Location - Description and detail of location of accident
  3. Details of vehicle involved - Registration number, description of vehicle, loading detail, vehicular defects
  4. Nature of accident - Details of collision, damages, injury and casualty
  5. Road and traffic condition - Details of road geometry, surface characteristics,type of traffic, traffic density etc..
  6. Primary causes of accident - Details of various possible cases (already mentioned) which are the main causes of accident.
  7. Accident cost - Financial losses incurred due to property damage, personal injury and casualty
These data collected need proper storing and retrieving for the following purpose. The purposes are as follows:
  1. Identification of location of points at which unusually high number of accident occur.
  2. Detailed functional evaluation of critical accident location to identify the causes of accidents.
  3. Development of procedure that allows identification of hazards before large number of accidents occurs.
  4. Development of different statistical measures of various accident related factors to give insight into general trends, common casual factors, driver profiles, etc.

Accident investigation

The accident data collection involves extensive investigation which involves the following procedure:
  1. Reporting: It involves basic data collection in form of two methods:
    1. Motorist accident report - It is filed by the involved motorist involved in all accidents fatal or injurious.
    2. Police accident report - It is filed by the attendant police officer for all accidents at which an officer is present. This generally includes fatal accidents or mostly accidents involving serious injury required emergency or hospital treatment or which have incurred heavy property damage.
  2. At Scene-Investigation: It involves obtaining information at scene such as measurement of skid marks, examination of damage of vehicles, photograph of final position of vehicles, examination of condition and functioning of traffic control devices and other road equipments.
  3. Technical Preparation: This data collection step is needed for organization and interpretation of the study made. In this step measurement of grades, sight distance, preparing drawing of after accident situation, determination of critical and design speed for curves is done.
  4. Professional Reconstruction: In this step effort is made to determine from whatever data is available how the accident occurs from the available data. This involves accident reconstruction which has been discussed under Section No.7 in details. It is professionally referred as determining “behavioral” or “mediate” causes of accident.
  5. Cause Analysis: It is the effort made to determine why the accident occurred from the data available and the analysis of accident reconstruction studies..