i witnessed a quite serious car crash earlier.
i was driving on the highway (2 lanes in each direction with a 1m concrete wall separating the 2 directions) when someone on the other side fell asleep on the wheel. in that particular place the other side had a concrete wall on the right side of the road as well to prevent debris falling from the mountainside. he hit the right wall, bounced off, hit head on the concrete wall in the middle, made a 180, hit the middle wall again with the back of the car and them rolled and came to a stop with the front of the car (or what was left of it) on the right wall.
luckily enough, the passengers got out with a few cuts and bruises and there wasn't any traffic to make the situation worse. i thought they would get more hurt since when they hit the middle wall the first time, the impact was so strong that the back wheels of the car jumped high enough to be seen over the wall.