Light Examination

Vehicle Visibility and Crash Analysis

Background: As a chain of school buses were making a left turn onto a road in early morning darkness, a motorcyclist laid down his motorcycle to avoid the bus traffic, then struck one of the buses in the side. At issue was the lighting condition of the motorcycle and the visibility of the school buses.

What We Did: A series of videotaped runs were made with an instrumented passenger car with and without headlights on to establish the baseline visibility of the buses in darkness (see photo). Once these were completed, an exemplar motorcycle was purchased and additional motorcycle runs were completed with and without a working headlight. A bulb inspection of the accident motorcycle headlight showed significant plastic deformation and oxidation/darkening of the filament, indicated that the headlight was operational when the bulb was fractured, but not proving one way or the other that the light was operational and fracture occurred when the accident happened.

As incandescent vehicle lighting has given way to quartz halogen, xenon and gas discharge lighting, the technology of lighting analysis has changed, and is changing rapidly. MARS is atop of the changes and ready to help, regardless of the lighting used.

Suzuki motorcycle used in accident.

Suzuki's front headlights.

Suzuki's rear lights.

School bus chain with reflective tape.