Vehicular accident reconstruction is the scientific process of investigating, analyzing, and drawing conclusions about the causes and events during a vehicle collision.
After a motor vehicle accident occurs, particularly one resulting in severe injuries or death, it will usually be investigated and sometimes be reconstructed. There are two primary types of people that perform these duties, the police and independent investigators.
The police will investigate an accident with the intention of determining if any criminal action took place in the accident. Some of the things the police look for are speeding, hours-of-service violations, mechanical violations, alcohol use, drug use, etc. For example, if a truck driver is exceeding his hours of service and causes a serious accident because he fell asleep at the wheel, he will likely be criminally charged. If that accident results in a fatality, the charge will likely be homicide.
With the accident investigation complete, an accident reconstruction can be performed. Reconstruction is the process of using physics to determine the speeds of the vehicles, and/or their relative positions at different times during the accident sequence. Information such as pre- and post-impact direction of travel, length of pre-impact skid marks, post-impact distances moved, friction values for the various surfaces the vehicles traveled over, point of impact, impact angles, and weights of the vehicles are all used as inputs into the equations used to reconstruct an accident.