I'm watching this movie, Final Run, in which a passenger train, traveling at high speed, loses control and becomes a runaway train. Some nonsense about some kind of new locomotive technology, and then the engineer spills coffee on the equipment, and, bang, there's no stopping the damn thing, and there's no switching to manual, if there is any kind of manual. The engineer tries to repair some fuses outside and gets electrocuted and falls off, so now no one is even pretending to be in charge.

A bunch of passengers with some skills try to solve the problem, to no avail. The locomotive just won't respond to anyone's efforts.

My question is: in order to save the passengers, wouldn't it be a good idea to try to uncouple the locomotive from the rest of the train? That way, the passenger cars would eventually come to a stop on their own, while the runaway locomotive could be dealt by some specialists up ahead, who would then have some options, including derailing the damn thing at some (safe) point.

What am I missing?

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    $\begingroup$ It seems that the movie is missing a good plot. $\endgroup$
    – NMech
    Nov 18 '21 at 7:38
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    $\begingroup$ Been “done” in lots of films. In reality they can be disconnected as that is how licomotives are changed and carriages added & removed. but if they are under load then not likely. $\endgroup$
    – Solar Mike
    Nov 18 '21 at 7:46
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    $\begingroup$ Pulling the communication cord will operate the train brakes pneumatically. Shutting off the fuel would stop the engine. There would be multiple circuit breakers and isolators available in the cab to switch off the traction control as it was probably a diesel electric locomotive. Any of those would stop the train. $\endgroup$
    – Transistor
    Nov 18 '21 at 12:22

US freight knuckle couplers can be unhooked at speed. A fictional coupler might work or might not. Couplers for other countries provide almost endless varieties.

US-style freight couplers can be unhooked at speed. This feature is used for a "flying switch." If the siding isn't reverse-facing and there is no way to do a runaround to get the locomotive to the other end of the train, the cars can be unhooked at speed, the locomotive accelerates away, and the switch is thrown between the locomotive and the cars, allowing the cars to move up the siding. The hand brake is then used to stop the cars. This is a very dangerous maneuver; I'm not sure if it is allowed by any Class 1 railroad. Also, if the locomotive is under power the release lever might be extremely difficult to throw.

Type H couplers are used in the US on passenger trains. These are tight-locking and prevent slack between cars, which is extremely undesirable in passenger operations. I believe that the uncoupling lever on these is typically locked and the locking mechanism would not be accessible from the train, nor would passengers have the tool required to unlock the lever.

A typical high speed train wouldn't even have the couplers accessible from the train; these cars are considered semi-permanently coupled.


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