CIE 104-1993

Lack of vehicle conspicuity is a large road safety problem judging both from accident statistics in the world, from accident-in-depth studies, and from road user explanations of collisions. One way to increase vehicle conspicuity also in daytime conditions is to equip the front of the vehicles with lights. In this report lights with this purpose are called Daytime Running Lights (DRL). Initially the variables that will influence vehicle daytime front conspicuity are analyzed. The results of various experimental studies are summarized. It is concluded that lights are an effective measure provided they have certain technical characteristics concerning intensity, light distribution, colour, number etc. Accident statistics from Finland, Sweden, Norway, USA where comparisons of vehicles with and without DRL have been carried out support the concept. The reduction of the daytime collisions due to DRL is estimated to be in the size of 10 percent. The reduction of daytime collisions between cars and unprotected road users is even larger. There are also some negative effects of DRL. However, these are judged to be of minor importance in comparison with the advantages.

Several countries have legislation for motorcycles to drive with the low beam turned on also during daytime. Some countries have legislation requiring low beam or special DRL for all vehicles during daytime (Finland, Sweden, Norway, Denmark). Canada has corresponding legislation for all new vehicles. The Economic Commission for Europe has produced a regulation for DRL. USA and some other countries do not require but allow DRL. The European Community has lately shown some interest in DRL as a road safety measure. However, except for the standard low beam as a DRL, the lighting specifications of DRL in most of these legislations, standards and regulations differ from each other.

Finally the report analyses what kind of lighting specifications should be required of a special DRL, what kind of standard vehicle lights could be accepted as DRL, and what special DRL-solutions could be recommended for motorcycles to improve vehicle conspicuity in an optimal way. For automobiles the recommendations for special DRL are two white lights each with a central intensity of 400-1200 cd and with a specified light distribution.

The report contains 20 pages with 1 figure.