Car accidents fall into several major categories (whose names are self-explanatory):

* Rear-end collisions
* Rollovers
* Head-on collisions
* Single-car accidents
* Pile-ups
* Railroad crossing accidents

Head-on collision

A head-on collision is one where the front ends of the ships, trains, planes or vehicles hit each other, as opposed to a side-collision or rear-end collision.

Road transport

In the context of freeways, such collisions are particularly difficult to avoid, since freeways were designed to facilitate high-speed travel. The resulting car accidents are often fatal.

Some U.S. states have installed special signage at freeway off-ramps to discourage drivers from going the wrong way.