SPEEDS, ACCIDENT RATES AND PERSONAL INJURY CONSEQUENCES FOR DIFFERENT ROAD TYPES

Roads with a high standard have the lowest accident rates, despite the fact that speeds on these roads are higher than on roads with a lower standard. Often overlooked is the fact that when accidents do occur the accident consequences expressed as the number of injured persons and the severity of the injuries, will be higher and worse respectively with higher speeds. What is required is an adaptation of the speed level so that a high road standard with low accident rates is also accompanied by acceptable accident costs. In this investigation, which covers accidents on the national roads during 1977-1981 reported by the police authorities, the following road types have been studied: motorways with speed limit 110 km/h (mv/110), motorways with speed limit 90 km/h (mv/90), two-lane roads with grade separation (half a motorway) with speed limit 110 km/h (ml/110), twolane roads (high standard) with speed limit 110 km/h (110), two-lane roads (normal standard) with speed limit 90 km/h (90), and two-lane roads (low standard) with speed limit 70 km/h (70). The accidents studied are primarily accidents with passenger cars in which a person in a car was injured. Speed data were obtained from the continuous speed measurements carried out by VTI. The investigation was a commission from the Swedish Road Administration. (Author/TRRL)