A rear-end collision (often called simply rear-end) is a traffic accident where a vehicle (usually an automobile or a truck) impacts the vehicle in front of it, so called because it thus hits its rear. It may also be a rail accident where a train runs into the rear of a preceding train.
Typical scenarios for rear-ends are a sudden deceleration by the first car (for example, to avoid someone crossing the street) the following car that does not have the time to brake and impacts the first at a road junction the following car accelerates more rapidly than the leading.
As a rule of thumb, impacting into another car is equivalent to impacting into a rigid surface (like a wall) at half of the speed. This means that rear-ending a still car while going at 30 mph is equivalent, in terms of forces, to impacting a wall at 15 mph. The same is true for the impacted vehicle.
A typical medical consequence of rear-ends, even in case of collisions at moderate speed, is whiplash.
For purposes of insurance and policing, the driver of the car that rear-ends the other car is almost always considered to be at fault due to not being within stopping distance or lack of attention. An exception to this rule comes into play if the impacted vehicle is in reverse gear. If the driver of the car that was rear-ended files a claim against the driver who hit him, said driver could be responsible for all damages to the other drivers car.
The Ford Pinto became the focus of a major scandal when it was alleged that a flaw in its design could cause fuel-fed fires as the result of a rear-end collision.
The Ford Crown Victoria which is commonly used as a police cruiser or taxi cab in many parts of the United States has also been the focus of safety investigations focused on a small number fuel tank explosions, in some cases causing injury or death, during rear end collisions. According to critics the Crown Victoria's design is flawed, with the location of the fuel tank within the rear crush zone designed to absorb impact during a rear end collision. Several police jurisdictions sued Ford over the vehicles alleged defects. For further discussion see Ford Crown Victoria.