Daylight Running Lights in Sweden—Pre-Studies and Experiences

The usage of daytime running lights in Sweden started at the end of the 60:ies. The behavioural studies of various measures to improve vehicle daylight conspicuity started at the same time. The conspicuity of oncoming vehicles was analyzed for drivers in real traffic. Brightness and colour contrast were found to be the most common causes to detection. The effect of different vehicle colours and lighted low beams on detection time was studied. The low beam condition was in all situations as good as the best colour. Many field experiments of peripheral detection as a function of running light intensity were carried out. Various types of running light systems were developed. The costs of a running light were calculated. A running light specification (intensity: 300 - 800 cd) and a law concerning its use (1 Oct. 1977) were written. The accident analyses indicate a very favourable effect of daylight running lights on collision accidents in daylight.