ROAD ILLUMINATION AND VEHICULAR TRAFFIC SAFETY

Traffic accident statistics indicate that the fatality rate on public roads and streets at night is 2 to 3 times greater compared with those of the day. Since the basic difference between night and day driving is the absence of light at night, the increase in the accident rate in the period of darkness can be mainly attributed to poor visibility conditions. In night driving the visibility distance largely depends upon the availability of artificial light, the source of light being the vehicle headlights or fixed overhead lighting. Studies carried out by various researchers and authoritative organizations determined that good quality lighting may reduce the accident rate up to 40%. Evidence that good lighting reduces night-time accidents and, in many instances improves road capacity, does not however authorize design engineers and highway administrators to use roadway lighting indiscriminately. Worsening economic conditions in various parts of the world and the continuous increase in energy costs demand a careful assessment of each individual case whether road lighting can be justified. The purpose of this paper is to review the basic driver's visibility needs, discuss the International and National lighting design standards and explore the impact of roadway illumination on vehicular traffic safety. (A) For the covering abstract of the conference see IRRD 860861.