Accident Investigators and Accident Reconstructionists routinely utilize tire marks as a means to understand the how, what, when, where and why of an accident. Tire marks can also provide a wealth of understanding of the vehicle dynamics at the time the tire marks are made on the roadway. Vehicles involved in an accident can produce many different types of tire marks. Not all tire marks are produced by locked wheels. Accident Investigators and Reconstructionists are trained to identify the type of tire mark that the vehicle produced whether it was a yaw, skid, or scrub mark.
It is important to understand that when a tire is locked and skidding, the tire provides no lateral stability to the vehicle. This lack of lateral stability means, in lay terms, that the driver will not be able to steer the vehicle when the front wheels skid and the vehicle will tend to spin when the back wheels are locked. In the past, the length of straight skid marks was used to determine the speed lost by the skidding vehicle. The dark, primarily straight skid marks were easy to observe, mark and measure to determine the change in speed. However, today, the majority of vehicles are equipped with anti-lock brakes ( ABS ) which are designed to prevent tire lockup and subsequent skidding.
ABS brakes, by virtue of preventing front wheel lockup, allow the driver to maintain directional control of the vehicle. Rear wheels that do not lock up prevent spins from occurring. The question becomes, “If there is no wheel lock up and therefore no skidding, how can the accident reconstructionist/investigator determine the speed lost by the vehicle during emergency/panic braking?” Vehicles equipped with ABS brakes will in fact leave faint tire marks on the roadway when the ABS system is activated. A trained accident reconstructionist/investigator can actually visualize, measure and document ABS tire marks. However, these marks are highly perishable and can become undetectable in a very short time on a heavily traveled roadway. This short time frame is measured in hours or minutes as opposed to days and weeks for locked-wheel skid marks.
For this reason, it is very important when dealing with a vehicular accident that CED Technologies Inc. engineers be contracted to arrive at the scene of the accident as soon as possible. This quick response time allows CED engineers to document and analyze crucial evidence that can be used to defend or pursue the accident with concrete evidence such as skid marks.
Senior Civil Engineer
Biomechanical / Mechanical Engineer