Buffer stop

The term "buffer stop" is of British origin, since railways in Great Britain principally use buffer-and-screw couplings between vehicles.

If there is extra room behind the bumper block, there is usually a sand or ballast drag that is designed to further retard a runaway train.

One such accident occurred in 1975 on the London Underground system, when a Northern City Line train powered past the bumper block at Moorgate station.

Largely because of its mass, a train transfers an enormous amount of kinetic energy in a collision with a buffer stop.

To improve stopping performance, a way of dissipating this energy is needed, through compression or friction.