Accident Investigations: Anti-Lock Braking and Tire Marks

In any transportation accident, proper identification of tire marks can play an important part. Each tire mark found is produced by a specific action of the vehicle during the accident. Tire marks can tell engineers and accident reconstructionists what the driver did, or may have attempted to do, prior to and after a collision. An important part of an accident investigation is point-of-impact (POI) or an area-of-impact (AOI), which tire marks may help to identify.

CED’s experts are often asked if cars with anti-lock brakes can prevent accidents and skid marks. Anti-lock Brake Systems (ABS) have been standard in most vehicles since the 1990’s. Brake experts anticipated that the introduction of ABS on passenger vehicles would reduce severity of accidents. The National Highway Traffic Safety Administration (NHTSA) found that while ABS did not reduce the number of total single-vehicle accidents, multi-vehicle crashes on wet roads were reduced by 24 percent, and nonfatal crashes by 14 percent (with ABS).

ABS equipped vehicles may still leave skid marks in an accident. The typical ABS skid has the same general appearance as a regular skid mark, but the mark is slightly lighter and is interrupted in a close pattern from the rapid lock-and-release of the brakes.

As explained in this CED article, although ABS braking leaves a fainter mark in an accident, engineers can still able to gather vital information by identifying the type of skid mark left by the tires as the accident occurred. The following are the types of marks engineers look to identify after an accident:

  • Yaw Mark – this type of mark is made by a tire that is rotating and sliding sideways parallel to that wheel’s axle; also referred to as sideslip or critical-speed scuff marks.
  • Scuffs – scuffs can be made by a rotating or yawing vehicle, vehicle acceleration, or a flat tire.
  • Skids – these are made by a locked wheel.
  • Prints – these are left by a rolling tire.
  • Scrub Mark – scrub marks are left by a wheel that locks due to damage.

Combining onboard data recorders and infotainment systems that provide important information with identification of tire marks and other physical evidence is an essential part of accident-reconstruction investigations. CED has a Transportation Group that specializes in various types of vehicle accidents.

When our CED engineers investigate a motor vehicle crash, they consider a variety of factors and evidence, including skid marks, operator actions, onboard data recorder and infotainment system reports, and mechanical defects. If you have a crash that requires reconstruction or expert opinion, please contact CED.