reports on injury accidents in 1969 have been analysed to compare road accident rates in daylight and darkness, and to investigate some of the factors which have an important bearing on accidents occurring in hours of darkness. the analyses have concerned the severity of injury, light conditions (daylight, darkness, or twilight), presence of street lighting (statistics available for the first time for many years), the state of the road surface (dry, wet or icy) class of road and speed limit. the main findings were: the dark accident rate of 1.64 accidents per million veh km was 1.33 times the daylight accident rate: the accident rate at dawn was 1.5 times the day-light rate due largely to the coincidence of dawn with the morning hours of peak travel in winter, whereas that at dusk was of the same order as in daylight; in darkness about 20 per cent more accidents occurred on wet roads than would be expected if roads were dry: three quarters of the dark accidents occurred on lit roads. the total cost of accidents in the dark was estimated at 142m. for the year. (a)

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