Abstract
There seems little doubt that the use of a single 21 c.p. running light in city driving in Indiana is associated with a real reduction in accidents per mile of travel. There is no evidence from this study which would show how much of this improvement is due to an increase in vehicle visibility and how much is due to non- visual factors incidental to the use of running lights, such as an increase safety consciousness of the drivers. Whatever the factors are, the use of a 21 c.p. running light in the city is an effective method for reducing accidents.