Final answer:
An underride collision is a type of collision where a portion of a passenger vehicle slides under another vehicle. It usually occurs when a smaller vehicle collides with a larger vehicle.
Step-by-step explanation:
The collision in which a portion of a passenger vehicle slides under another vehicle is known as a underride collision. This type of collision occurs when a smaller vehicle collides with a larger vehicle and slides underneath it. This can happen, for example, when a car collides with a truck or a trailer.
In an underride collision, the smaller vehicle can slide under the larger vehicle due to the difference in height and structure. This can result in severe damage to the smaller vehicle and pose a significant risk to the occupants.
To prevent underride collisions, many modern vehicles are equipped with rear underride guards, also known as DOT guards or ICC bars, which are designed to prevent smaller vehicles from sliding underneath in the event of a collision.