Current and prior field test data suggest that use of daytime running lights on operating vehicles can reduce the frequency and severity of collisions. Currently available data do not support the establishment of optimal or required daytime running light output and light distribution parameters. Daytime running light configurations which have been used in field tests range in output from low beam headlights to vehicle parking lights. Considerations of cost and driver visual response suggest that an optimal daytime running light would fall between these extremes. Photometric measurements were taken using parking lamp units from vehicles currently being used in daytime running light field tests. The vehicles in question all use a special bulb having a 15 candela spherical intensity. Because of differences in lamp housings and lenses, the vehicles in question vary in terms of apparent output and angular distribution. Photometric measurements of the lamps in question were taken over a range of viewing angles. A weighting scheme was developed to combine the angular measurements into a figure of merit for each vehicle. These data can be used in the final analysis of field test results to evaluate the functional relationship between daytime running light output and accident rate.
Abstract