Bicycle lighting and conspicuity.

This study examined bicycle-motor vehicle crash data for evidence of the role of bicycle lighting, carried out field tests of the apparent brightness of bicycle head and tail lights, and laboratory measurements of the characteristics of the light beam emitted by each light. There was reasonable agreement between the field and laboratory tests. Bicycle head lights have a dual role of providing illumination for the path ahead, and providing conspicuity for angles up to 90 degrees to the side. Similarly, tail lights should provide conspicuity for angles up to 90 degrees to the side, as well as from the rear. (a)