The National Highway Traffic Safety Administration conducted the National Motor Vehicle Crash Causation Survey of crashes involving light passenger vehicles, with a focus on the factors related to pre-crash events. The survey used a statistical sample of the 4,031,000 vehicles, 3,945,000 drivers, and 1,982,000 passengers that were estimated to have been involved in crashes between 2005 and 2007. The survey tried to identify the critical reason for the crash which is the last event in the crash causal chain.

The survey found that the critical reason was assigned to the driver in 94 percent (±2.2%)† of the crashes. In about 2 percent (±0.7%) of the crashes, the critical reason was assigned to a vehicle component’s failure or degradation, and in 2 percent (±1.3%) of crashes, it was attributed to the environment (slick roads, weather, etc.).

In the overwhelming majority of car crashes it is the driver’s error that lead to the crash. In only four percent of the cases was there truly an accident.