University of California Transportation Center

Pedestrians and cyclists have little physical protection. Unlike the inhabitants of automobiles, they are not surrounded by rigid frames and such protective devices as airbags. Yet when pedestrians and cyclists share the roadway with automobiles, as they often do, the chance of collision with severe damage is high. In part, this is due to the great disparity of speeds involved. Pedestrians typically move quite slowly compared to the speed of automobiles, and the speed of bicycles is usually intermediate. Similarly, automobiles are much heavier and thus are capable of causing much more damage to the things with which they collide.