# Freight Train Safety Mechanism Question **URL:** \ **Category:** Factual Questions\ **Created:** [December 17, 2002, 11:18pm UTC](https://boards.straightdope.com/t/freight-train-safety-mechanism-question/143443 "2002-12-17T23:18:07Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![TheLoadedDog](https://avatars.discourse-cdn.com/v4/letter/t/35a633/32.png) [@TheLoadedDog](https://boards.straightdope.com/u/TheLoadedDog)\ **Post date:** [December 17, 2002, 11:18pm UTC](https://boards.straightdope.com/t/freight-train-safety-mechanism-question/143443/1 "2002-12-17T23:18:07Z")
From [this article](http://www.dailytelegraph.news.com.au/common/story_page/0,5936,5696766%255E21302,00.html) about three teenagers attempting to derail a train by putting stuff on the track, comes this: > [@](#): > > A 1.2km freight train, with 45 carriages, struck the device at relatively low speed and the driver immediately applied the train’s airbrakes. > > The brakes are believed to have triggered a safety mechanism which split the rear half of the carriages from the front half, allowing the front end of the train to come to a stop sooner. I don’t quite get this. Assuming the journalist didn’t mean “sooner than the back of the train” ( wouldn’t the back of the train just smash into the front anyway, and drive it forwards - the entire thing stopping as one unit? ), and meant “sooner than it would otherwise have”, how does it work? If the emergency brakes are applied to each freight car at the same time anyway, wouldn’t it make no difference to braking efficiency whether or not some or all of them are still coupled, as each car would more or less be responsible for arresting its own momentum? I was also under the impression that conventional railway wisdom was that,in an emergency situation, a lot of importance is placed on keeping the train in one piece, so that if it derails, it will stay close to the track alignment, and not end up as individual wagons scattered across the landscape. This train-splitting device would seem to contradict that thinking. Any train buffs out there have ideas on this? ---
**Author:** ![bernse](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@bernse](https://boards.straightdope.com/u/bernse)\ **Post date:** [December 17, 2002, 11:34pm UTC](https://boards.straightdope.com/t/freight-train-safety-mechanism-question/143443/2 "2002-12-17T23:34:20Z")
> [@](#): > > The brakes are believed to have triggered a safety mechanism which split the rear half of the carriages from the front half, allowing the front end of the train to come to a stop sooner I’m not the worlds biggest train buff by any stretch, but I do have family that has been on the railroads for years so I’ve heard of quite a bit (and gone on a number of rides). I have no idea what he means by this. Maybe he just means that since it came uncoupled, the front end of the train stopped faster (the end with the power)? That would make sense I suppose since if that happened, you’d also have the stopping force of the power (engines) and with their Dynamic brakes in addition to the air brakes that would probably stop faster since it wouldn’t have the extra tonnage. Best guess… I dunno. 😕 ---
**Author:** ![David\_Simmons](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@David\_Simmons](https://boards.straightdope.com/u/David_Simmons)\ **Post date:** [December 17, 2002, 11:42pm UTC](https://boards.straightdope.com/t/freight-train-safety-mechanism-question/143443/3 "2002-12-17T23:42:16Z")
It sounds to me like the reporter garbled the explanation from railroad people and then telephoned the report in to a rewriter who further garbled it. And then the pressroom dropped the page of type and didn’t have time to reset it.