Katherine Bickford

Two train derailers on the Esquimalt & Nanaimo (E&N) line

A derail or derailer is a device used to prevent blocking or compromising a rail track (or collision with anything present on the track, such as a person, or a train) by unauthorized movements of trains or unattended rolling stock. The device works by derailing the equipment as it rolls over or through it where there is a risk of damage to equipment, injury or death if equipment is allowed to proceed past the derail point.