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An analysis of expressway accidents in Singapore using GIS
- Accident based on vehicle involvement
The accidents are also grouped based on the vehicle involvement and it has been observed that around 58% of the expressway accidents were multiple vehicle accidents and the rest were single vehicle accidents. Further the collision of vehicle with stationary objects has been more in accident-prone areas. On the other hand even though most of the multiple vehicle accidents are caused as a result of head to rear type of collision, the percentage of sideswipe collision is found to be more in accident-prone areas, which needs to be focused. Hence analysis of specific types of accidents may reveal important geometric and traffic control and regulatory factors which are responsible for their causation.
Fig.4: Accident-Prone Areas: Spatial distribution of accidents by vehicle involvement
Further while investigating the distribution of accidents over different times of the day, it is found to be about uniform over the evening peak and night time but slightly higher during the morning peaks. Fatality percentage is clearly higher during night. When considering the speed limit there is a clear demarcation between the accident percentage contribution (around 85%) at the maximum speed limit zones (80 km/hr) and the other less speed limit zones. These types can also be visually studied for their distribution patterns.
Framing various combinations of above accident types can still improve the analysis. They help to localize accidents and thus arrive at some more useful conclusions. Further the determination of accident-prone areas can well be approached using only accidents that result in personal injury or death, as the cause of such severe accidents cannot be reasonably attributed to randomness. There must be some deficiency with respect to the geometric features of the roadway or in traffic control and regulatory factors. Hence by proceeding in this way and having the information about the spatial distribution of accidents it is possible to model the accidents with different geometric, traffic control/ regulatory factors and environmental factors that might be responsible for a particular type of accident.
Conclusion and Recommendations
The Geographic Information System is an effective tool to display different type of spatial accident distribution on digital road network. The use of GIS enables relevant accident data to be quickly processed and displayed on a map. GIS has also been used as a tool to identify hazardous locations along the expressways depending on the historical road accident data. These in turn will help to improve the safety of road by advanced planning and maintenance of the so-called accident-prone areas. For further development of the present model, the expressway database can be manipulated by adding roadway geometrics, information about traffic control and regulatory factors, flow data at different stretches of those areas. These information will then consist of the data that can be easily accessed or referred when crucial decision have to be made in relation to the type of improvement to be done at that particular area.
References
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