Day Time Running Lights

Published on 7 March 2003 by Gill

Review of the Evidence for Motorcycle and Motorcar Daytime Lights.

Summary.

The paper reveals the defects of method, conduct or findings of Janoff et al 1970, Andersson et al 1976 and the other main monitoring studies to date of the effect of motorcycle and motorcar daytime light laws. It weighs up the prima facie arguments for and against motorcycle and motorcar daytime lights, and predicts that on balance motorcar daytime lights may manifest a net safety disbenefit. It approves the method of Olson et al 1981's motorcycle gap acceptance experiment, but notes the limited import of the findings. It finally canvasses how ostensible motorcycle 'conspicuity' accidents that in fact have other causes can be prevented.

Abstract

The accepted remedy for motorcycle-and to a lesser extent also motorcar-'conspicuity' accidents with other vehicles or pedestrians in daytime is daytime lights.

So in 2002 the European motorcar manufacturers (ACEA) made an offer to the European Union to fit daytime lights to all new motorcars; and shortly after the European motorcycle manufacturers (ACEM) agreed amongst themselves also to fit them to all new motorcycles.

Against this background, the paper first, 'negatively', critically reviews the main evidence and arguments that motorcycle (or motorcar) daytime lights are effective to reduce accidents. In the course of the review the paper:

a) Reveals the defects of method, conduct or findings of Janoff et al 1970, Andersson et al 1976, and the other main monitoring studies to date of the effect of motorcycle (or motorcar) daytime light laws;

b) Concludes on the balance of the prima facie arguments for and against the use of motor car (and motorcycle) daytime lights that an overall net safety benefit from daytime lights is not assured - indeed a net safety disbenefit from motorcar daytime lights cannot be discounted; and

c) Considers the highly persuasive-but time and place specific-findings of Olson et al 1981's experimental field study of the effect of motorcycle daytime lights upon the gap acceptance behaviour of ordinary motorcar drivers in Ann Arbor, Michigan.

The paper second, 'positively', describes the other possible causes of an ostensible motorcycle daytime 'conspicuity' accident besides an actual 'Lack of conspicuity of the motorcycle', such as 'Obscuration of the motorcycle' or 'Arbitrary estimation of the motorcycle's speed'.

It describes the research that remains to be conducted in order formally to establish the causes in question. The paper finally canvasses some of the important means of prevention of motorcycle 'conspicuity' accidents that might potentially flow from successfully establishing the causes.

Last updated/reviewed 23/9/04