What is the primary use of test skids in crash reconstruction?

What is the primary use of test skids in crash reconstruction?

• A. Used to determine drag factor
• B. Must complete atleast 2 test skids which must be within 5% of each other
• C. Always use longest skid
• D. Conditions must be similar to those of the accident

Answer: (A)

Test skids are performed to determine the drag factor of the road surface and tires under the actual conditions of the crash. The drag factor is a coefficient that represents how much resistance slows a vehicle, combining road surface quality, tire condition, weather, and any contaminants. Knowing this coefficient lets investigators convert skid length into a speed estimate using the deceleration data through the stopping-distance relationship. In other words, the speed at which the vehicle was moving when braking began (or at impact) is inferred from how far it skidded, once the friction level is known. While conducting skids under conditions similar to the crash and sometimes repeating tests for reliability can be part of the process, the core purpose remains determining the drag factor so accurate speed calculations can be made.

Test skids are performed to determine the drag factor of the road surface and tires under the actual conditions of the crash. The drag factor is a coefficient that represents how much resistance slows a vehicle, combining road surface quality, tire condition, weather, and any contaminants. Knowing this coefficient lets investigators convert skid length into a speed estimate using the deceleration data through the stopping-distance relationship. In other words, the speed at which the vehicle was moving when braking began (or at impact) is inferred from how far it skidded, once the friction level is known. While conducting skids under conditions similar to the crash and sometimes repeating tests for reliability can be part of the process, the core purpose remains determining the drag factor so accurate speed calculations can be made.