A.D. Tupper & Associates Limited

It takes energy to produce damage on a vehicle and all things being equal, more damage means more energy which means more speed. Knowing the depth of crush, and the stiffness of those pieces which were bent, it is possible to calculate the amount of energy needed to produce the damage on both of the cars, and to derive the change in velocity that each car experienced during the impact phase of the collision.

Typically, this analysis is done by computer and can produce good results if there are good measurements of the crush depth, and a good assessment of the stiffness of the vehicle components.

Crush depths can be measured directly in the field or indirectly from photographic data, and stiffness factors can be obtained from controlled tests.

The velocity change derived from the energy calculations, can then be combined with other analyses to determine the initial speed of the vehicles at the point of impact.