There are many different possible causes of a rear-end collision, but all of them involve the rear driver moving faster than the car in front. This might mean that the front car is stopped at an intersection, slowing down because of upcoming traffic or a pedestrian crossing, or even parked. In many cases, the rear driver is either driving too fast to come to a complete stop before colliding with the car in front, is distracted and doesn’t notice the car in front of them is stopped, or may be experiencing some sort of mechanical issue like bad brakes. In Northern California, ice can also be a factor in rear-end collisions, but it is highly unlikely that ice will ever play a role in a rear-end collision in Southern California.

Some rear-end collisions may ultimately lead to multiple-car pileups, meaning that the lead car of the initial impact is forced forward into the vehicle in front of them, or the rear vehicle is then collided into by the vehicle behind them because of the abrupt stop. In some cases, multiple car pileups can involve several vehicles and cause major injuries to many people. In these cases, it can become very complicated to determine who was originally at fault, and even a simple interaction with the other insurance companies can be extremely frustrating and confusing.