The Mechanics of Pedestrian Collisions

Pedestrian collisions can make tough cases.

That's usually because (1) the pedestrian doesn't remember very much about getting hit and (2) the driver who hit them is pretty motivated to make it someone else's fault.

But, interestingly, it's not all "he said, she said."

The crashes themselves seem violent, random and extremely unpredictable. But from this chaos very distinct patterns emerge.

There are four distinct types of pedestrian "actions" after a collision:

• Forward Projection

• Roof Vault

• Fender Vault

• Dragging/Run-Over

Each of these actions is going to be associated with different types of injuries and damage to the vehicle.

These have all been observed in thousands of collisions and studied in detail with simulated impacts in the laboratory.

This information can be used to "triangulate" what actually happened and give a very good sense--even without witness testimony--of whether a pedestrian dashed out in front of an oncoming vehicle or the vehicle drifted across the fog line and hit the pedestrian.

And it gets even better if the event data recorder (EDR) can be interrogated and data about, e.g., sudden braking can be downloaded.

Science is neat. Especially when it--in a very clean and objective way--cuts through the layers of bias that are an inevitable part of any collision where someone is seriously injured.