Accidents on a section of Thailand's super highway

A study was made of 842 reported accidents over three and half years on the Bangkok to Saraburi super highway (103 km). Accidents were classified by use of the road user movement (RUM) code and also coded for location. The analysis separated intersection accidents from link accidents and summaries printed by computer of the results at each individual location. The most frequent rum was determined and the problem intersections readily identified. To examine the link accidents a statistical quality control technique was employed to normalise the effects of varying link length. Detailed examination of the worst locations lead to the preparation of collision diagrams and the inspection of physical conditions. The highway link from the Nava Nakon intersection (46.1 Km) to the Nakon Sawan intersection (52.1 Km) was determined to be the highest accident frequency link of the most frequent rum type (running into the median). Of the 64 intersections along the 103 km section, nine had more than five accidents of any type within the three and half year period and of these, five had more than five accidents of a single specific RUM. For all accidents along the route, 'running into the median' accidents accounted for approximately 30 per cent of the total and was by far the biggest problem. This was the first application of such a technique to thai accident data and was able to highlight its value in determining the particular nature of accident problems.