Trained traffic collision reconstructionists can look at the light bulbs inside a vehicle’s headlamps and tail lights to determine if these lights were on or off at the time of collision. In many cases, this information can be quite valuable. If at the time of collision, headlamps or tail lights were not properly illuminated – and they should have been, this can be evidence of fault. A bulb’s filament can be used by a reconstructionist to make this determination. The terminology is: Hot Shock (evidence that the bulb was illuminated at the time of collision) and Cold Shock (evidence that the bulb was off at the time of collision).
The following are examples of this evidence:
This bulb contains evidence of Cold Shock. The filament of this bulb broke apart without stretching.
This bulb contains evidence of Hot Shock. The filament of this bulb stretched and was deformed after this impact.