While handling automobile accident claims, the issue of whether lights were on or off at the moment of impact may arise. Inspection of the vehicles involved may provide
evidence as to the answer to this question.
The damaged vehicle in Figure 1 has
automobile lamps still in the vehicle, allowing physical evidence as to whether
the lights were on or off to be identified.
This article reviews several case studies of
automobile lights and what information
can be deduced regarding whether the
lights were on or off.
In Figure 2A, the bulb is a standard
sealed beam 1157 bulb found in many
tail light assemblies. Figure 2B is a bulb
extracted from the rear impact area of a
vehicle. The bulb was not fractured, but
the filament, as indicated by the arrow, is
When the light is incandescent (on),
the filament is very hot and ductile,
which means it deforms easily. The forces
of the impact cause the deformation. If
the light had been off, no deformation
would be noted since the cold filament is
much more rigid.
The deformed filament in Figure 2B
suggests that the light was incandescent at
the time of impact. Likewise, the halogen
lamp on the right in Figure 3 is deformed
when compared to a new lamp shown on
the left, suggesting it was incandescent at
the time of the accident.
Another condition observed in lamps
that were incandescent at the time of the
accident is the formation of a small ball of
tungsten, as shown by the arrow in Figure
4. During impact, a filament may break,
and as this occurs, it generates an electric
arc, causing a high temperature and the
formation of a melted ball of tungsten.
The filament in Figure 4 was incandes-
cent at the time of the accident.
In Figure 5, the bulb has fractured and
a small chard of glass is found melted
Shedding Some Light
on Auto Accidents