A detonator is a coin-sized explosive device equipped with lead straps that secure it to the railhead. When a locomotive wheel crushes it, it fires with a loud bang that can be heard clearly inside the cab. It is used to protect work zones, disabled trains, or fouled tracks, forcing an approaching engineer to immediately reduce speed or stop.
The flagman walked back a mile and put down three detonators to protect our rear.
In North America, this device is almost universally called a torpedo; detonator is the British and Commonwealth equivalent.
Also heard as
- torpedo
Related terms
Torpedo
A small explosive charge strapped to the railhead that detonates with a loud bang to warn oncoming trains.
Red flag
A physical red cloth used to signal an absolute stop to an approaching train.
Track warrant
A written authority from the dispatcher, copied by radio, that lets a train occupy a set stretch of main track.