Rear-end crashes are among the most common types of motor vehicle accidents, but they are an especially serious problem when a semi-truck is involved. Commercial trucks can legally weigh as much as 80,000 pounds – up to 40 times more than the average passenger automobile – and they are capable of causing devastating physical damage when they plow into another vehicle. Their immense size also makes them more likely to be involved in a rear-end collision, since they take far longer to come to a complete stop. For example, a passenger vehicle traveling at 55 miles per hour can stop within 400 feet, whereas a large truck will require twice that distance to stop when traveling at the same speed.
A semi-truck rollover may be caused by sudden gusts of high speed winds, such as those which are common on the high plains, but a more common cause of rollover is the failure of the truck driver to safely navigate a corner or a turn at an intersection. Every truck has a rollover threshold, which is its ability to resist the centrifugal forces which cause a truck to roll over, and cornering at a speed which exceeds this threshold makes it all but certain that the truck will tip over. In some cases, a vehicle which is traveling alongside the truck may be crushed, while in other cases the accident victims are injured when their vehicles crash into the truck lying across the road.
One of the most dramatic types of truck accident is the jackknife accident, which derives its name from its similarity to the motion of a jackknife as it swings shut. If a truck driver suddenly hits the brakes too hard or too quickly, the trailer is liable to swing forward, pivoting on the trailer hitch in the direction of the cab. Anyone who has the misfortune of traveling alongside the truck at the time that this occurs is likely to be caught up by the trailer as it swings forward, and the accident victims may even be pinned between the trailer and the cab. Those who are following the truck at the time of the accident are liable to be involved in the crash, as their own vehicles collide with the trailer as it sits across the road presenting a barrier for oncoming traffic.
Perhaps the most horrific variety of truck accident occurs when a passenger automobile crashes into the back end of the truck trailer. Semi-truck trailers should all have underride guards installed on the bottom of the rear, since this strong metal frame can save lives in the event of an accident. If the underride guard crumples – or is not there in the first place – the smaller vehicle may slide underneath the trailer, with the result that the bottom of the structure is likely to shred through the engine compartment and sometimes into the passenger area of the automobile.