# Does a train really jerk backwards at the moment that it comes to a complete stop? **URL:** \ **Category:** Factual Questions\ **Created:** [June 20, 2021, 9:16pm UTC](https://boards.straightdope.com/t/does-a-train-really-jerk-backwards-at-the-moment-that-it-comes-to-a-complete-stop/944705 "2021-06-20T21:16:18Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![hibernicus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hibernicus/32/2802_2.png) [@hibernicus](https://boards.straightdope.com/u/hibernicus)\ **Post date:** [June 24, 2021, 10:05pm UTC](https://boards.straightdope.com/t/does-a-train-really-jerk-backwards-at-the-moment-that-it-comes-to-a-complete-stop/944705/21 "2021-06-24T22:05:09Z")
This is a really interesting discussion - thanks everyone for your thoughtful replies. It’s clear that the effect (real or not) is maximised when the braking effect is maintained right up to the moment that the vehicle comes to a stop, and that it can be mitigated by progressively easing up on the brakes. By the same token, it would be most noticeable in an emergency braking situation, where passengers would be thrown forwards at the sudden onset of maximum deceleration, and (apparently) thrown backwards when the deceleration suddenly stops. ---
**Author:** ![Mr\_Downtown](https://avatars.discourse-cdn.com/v4/letter/m/8e8cbc/32.png) [@Mr\_Downtown](https://boards.straightdope.com/u/Mr_Downtown)\ **Post date:** [June 25, 2021, 4:04am UTC](https://boards.straightdope.com/t/does-a-train-really-jerk-backwards-at-the-moment-that-it-comes-to-a-complete-stop/944705/22 "2021-06-25T04:04:41Z")
> [@Machine\_Elf](#): > > the conductors of regular trains often neglect to ease up on the brakes Conductors are the guys walking around inside the train, and have no control over braking. (This mistaken usage has become extremely widespread in the US and I’m not sure why.) The train’s driver (“engineer” in American English) operates the brakes. ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [June 25, 2021, 5:00am UTC](https://boards.straightdope.com/t/does-a-train-really-jerk-backwards-at-the-moment-that-it-comes-to-a-complete-stop/944705/23 "2021-06-25T05:00:46Z")
I wondered about “conductor” as well but thought it must be a local Japanese usage. In New Zealand the conductor is called a train manager. The driver is called a locomotive engineer, often shortened to “LE” in the business, but “driver” is also used casually. ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [June 25, 2021, 5:19am UTC](https://boards.straightdope.com/t/does-a-train-really-jerk-backwards-at-the-moment-that-it-comes-to-a-complete-stop/944705/24 "2021-06-25T05:19:01Z")
> [@Mr\_Downtown](#): > > Train brakes aren’t that sophisticated; they are set or released. All wheels get the same impulse, whether an air brake piston or the electric current used for dynamic braking (on trams and some rapid transit trains). Leaks in hoses and other vagaries mean all the wheels in a freight train don’t get the same resistive force—but they all get the brakes applied and released at essentially the same time. I think it’s slightly more complicated than that. As I understand it, the locomotive’s brakes can be applied or released separately from the wagon’s, helping with “stretch braking” where tension is maintained on the couplings during braking. ---
**Author:** ![TokyoBayer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tokyobayer/32/13989_2.png) [@TokyoBayer](https://boards.straightdope.com/u/TokyoBayer)\ **Post date:** [June 25, 2021, 6:12am UTC](https://boards.straightdope.com/t/does-a-train-really-jerk-backwards-at-the-moment-that-it-comes-to-a-complete-stop/944705/25 "2021-06-25T06:12:06Z")
> [@Machine\_Elf](#): > > The Shinkansen conductors are much better at easing up on the brakes at the end (maybe a job requirement, to line up the train doors with the platform gates?); if you’re on board and close your eyes, it can be hard to tell when you’ve come to a complete stop. See Post 8, they train them to do that. Local trains also need to stop on the stop lines, but they are on a much tighter schedule so you see them clamp the brakes occasionally. I have also seem the overshoot the line and need to back up. That’s embarrassing for the driver. ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [June 25, 2021, 7:12am UTC](https://boards.straightdope.com/t/does-a-train-really-jerk-backwards-at-the-moment-that-it-comes-to-a-complete-stop/944705/26 "2021-06-25T07:12:52Z")
> [@TokyoBayer](#): > > I have also seem the overshoot the line and need to back up. That’s embarrassing for the driver. In New Zealand you need special authorisation to back up (set back), so everyone on the radio channel knows what’s happened. ---
**Author:** ![Melbourne](https://avatars.discourse-cdn.com/v4/letter/m/b5e925/32.png) [@Melbourne](https://boards.straightdope.com/u/Melbourne)\ **Post date:** [June 25, 2021, 7:20am UTC](https://boards.straightdope.com/t/does-a-train-really-jerk-backwards-at-the-moment-that-it-comes-to-a-complete-stop/944705/27 "2021-06-25T07:20:50Z")
> [@Richard\_Pearse](#): > > In New Zealand you need special authorisation to back up (set back), so everyone on the radio channel knows what’s happened. Or sometimes, (around here) doesn’t backup, and doesn’t open the doors. I’m sure that the rules here have changed over the years: back when the passengers controlled the doors, they _would_ back up, or else risk passengers jumping out. I’ve never seen a passenger train here settle back after coming to a stop. ---
**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\ **Post date:** [June 25, 2021, 7:52am UTC](https://boards.straightdope.com/t/does-a-train-really-jerk-backwards-at-the-moment-that-it-comes-to-a-complete-stop/944705/28 "2021-06-25T07:52:31Z")
> [@TokyoBayer](#): > > That’s embarrassing for the driver. [pulls out sword, commits seppuku on platform] ---
**Author:** ![Spoons](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spoons/32/3141_2.png) [@Spoons](https://boards.straightdope.com/u/Spoons)\ **Post date:** [June 25, 2021, 8:02am UTC](https://boards.straightdope.com/t/does-a-train-really-jerk-backwards-at-the-moment-that-it-comes-to-a-complete-stop/944705/29 "2021-06-25T08:02:30Z")
> [@Mr\_Downtown](#): > > The train’s driver (“engineer” in American English) operates the brakes. It’s “engineer” or “operator,” but never “conductor” in Canadian English. A friend of mine proudly called himself an operator of Canadian Pacific trains, and he would tolerate being called an engineer (“Engineers design bridges, but okay, fine”), but he would always point out that train conductors, in Canada anyway, had an entirely different job, and most could not operate an engine at all. ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [June 25, 2021, 8:27am UTC](https://boards.straightdope.com/t/does-a-train-really-jerk-backwards-at-the-moment-that-it-comes-to-a-complete-stop/944705/30 "2021-06-25T08:27:54Z")
Here the Wellington metro train doors are controlled by the passengers but only after the Train Manager has released the appropriate doors. I think the drivers can also override doors to keep them shut. So the train stops at the appropriate mark for the length of train, the train manager releases the appropriate doors (not the ones that open onto the adjacent track!) and only then may the passengers open the doors themselves. If the driver misses the mark by a little bit, the train manager can prevent passengers from opening doors that don’t open to the platform. If the train does need to set back then it just needs verbal authorisation from the Train Controller. The Train Controller is in charge of all movements on their part of the rail network, they do signalling, verbal authorisations for setting back, arrange crossing of trains in single track areas, that sort of thing. ---
**Author:** ![TokyoBayer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tokyobayer/32/13989_2.png) [@TokyoBayer](https://boards.straightdope.com/u/TokyoBayer)\ **Post date:** [June 25, 2021, 8:37am UTC](https://boards.straightdope.com/t/does-a-train-really-jerk-backwards-at-the-moment-that-it-comes-to-a-complete-stop/944705/31 "2021-06-25T08:37:09Z")
> [@Richard\_Pearse](#): > > In New Zealand you need special authorisation to back up (set back), so everyone on the radio channel knows what’s happened. In the 20 plus years of riding Tokyo area trains, it only happened a few times. I wonder if they have to get special authorization as well. They really punish drivers who make mistakes and that punishment and punitive retraining system lead to a [really deadly train accident](https://en.wikipedia.org/wiki/Amagasaki_derailment) after the driver needed to back up. > [@](#): > > It occurred when a seven-car [commuter train](https://en.wikipedia.org/wiki/Commuter_train) came off the tracks on [West Japan Railway Company](https://en.wikipedia.org/wiki/West_Japan_Railway_Company)’s (JR West) [Fukuchiyama Line](https://en.wikipedia.org/wiki/Fukuchiyama_Line) in just before [Amagasaki Station](https://en.wikipedia.org/wiki/Amagasaki_Station_(JR_West)) on its way for Dōshisha-mae via the [JR Tōzai Line](https://en.wikipedia.org/wiki/JR_T%C5%8Dzai_Line) and the [Gakkentoshi Line](https://en.wikipedia.org/wiki/Gakkentoshi_Line), and the front two cars rammed into an [apartment building](https://en.wikipedia.org/wiki/Apartment_building). The first car slid into the first floor parking garage and as a result took days to remove, while the second slammed into the corner of the building, being crushed against it by the weight of the remaining cars. Of the roughly 700 passengers (initial estimate was 580 passengers) on board at the time of the crash, 106 passengers, in addition to the driver, were killed and 562 others injured. > [@](#): > > Investigators primarily focused on the speeding by the 23-year-old driver, later identified as Ryūjirō Takami (who was among the dead), as being the most likely cause of the derailment. Twenty-five minutes before the derailment, the driver had [run a red signal](https://en.wikipedia.org/wiki/Signal_passed_at_danger), causing the [automatic train stop](https://en.wikipedia.org/wiki/Automatic_train_stop) (ATS) to bring the train to a halt.[[2]](https://en.wikipedia.org/wiki/Amagasaki_derailment#cite_note-Seconds_from_Disaster-2) The train had also overshot the correct stopping position at an earlier stop at [Itami Station](https://en.wikipedia.org/wiki/Itami_Station_(JR_West)), **requiring him to back up the train** , and resulting in a 90-second delay,[[1]](https://en.wikipedia.org/wiki/Amagasaki_derailment#cite_note-journal465-1) about four minutes before the disaster.[[2]](https://en.wikipedia.org/wiki/Amagasaki_derailment#cite_note-Seconds_from_Disaster-2) By the time the train passed [Tsukaguchi Station](https://en.wikipedia.org/wiki/Tsukaguchi_Station_(JR_West)) at a speed of 120 km/h, the delay had been reduced to 60 seconds.[[1]](https://en.wikipedia.org/wiki/Amagasaki_derailment#cite_note-journal465-1) ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [June 25, 2021, 8:41am UTC](https://boards.straightdope.com/t/does-a-train-really-jerk-backwards-at-the-moment-that-it-comes-to-a-complete-stop/944705/32 "2021-06-25T08:41:23Z")
Wow, that’s an unfortunate chain of events. My partner drives metro trains. The fear of being caught speeding would far outweigh the fear of being late here. ---
**Author:** ![TokyoBayer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tokyobayer/32/13989_2.png) [@TokyoBayer](https://boards.straightdope.com/u/TokyoBayer)\ **Post date:** [June 25, 2021, 8:59am UTC](https://boards.straightdope.com/t/does-a-train-really-jerk-backwards-at-the-moment-that-it-comes-to-a-complete-stop/944705/33 "2021-06-25T08:59:29Z")
> [@Richard\_Pearse](#): > > The fear of being caught speeding would far outweigh the fear of being late here. This accident occurred while I was in Japan and they had a special on the punishment system for the drivers, and how that humiliation was seen as a likely cause of the accident. From the same linked article. > [@](#): > > Drivers for JR West face financial penalties for lateness as well as being forced into harsh and humiliating retraining programs known as _nikkin kyōiku_ (日勤教育, “dayshift education”), which include weeding and grass-cutting duties during the day. They have that culture of never being late, but this was the unfortunate outcome. ---
**Author:** ![The\_Librarian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/the_librarian/32/402_2.png) [@The\_Librarian](https://boards.straightdope.com/u/The_Librarian)\ **Post date:** [June 25, 2021, 9:01am UTC](https://boards.straightdope.com/t/does-a-train-really-jerk-backwards-at-the-moment-that-it-comes-to-a-complete-stop/944705/34 "2021-06-25T09:01:44Z")
The effect you are noticing is the transition between dynamic and static friction (the little jerk). The locomotive rolling back a couple of inches is the delay in releasing the brakes and the elasticity of the train (after the whole train has stopped, the brakes are released (last car last) causing the locomotive to be “pulled back” by the last car: The whole train is stretched out a little bit during braking and goes back to normal when all brakes are released with the brakes on the last car the latest to release. If the brakes all release at the same time the locomotive only goes back 1/2 the distance (depending on the center of gravity of the train). ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [June 25, 2021, 12:37pm UTC](https://boards.straightdope.com/t/does-a-train-really-jerk-backwards-at-the-moment-that-it-comes-to-a-complete-stop/944705/35 "2021-06-25T12:37:03Z")
> [@TokyoBayer](#): > > See Post 8, they train them to do that. In post 8 you were speaking of deceleration, i.e… the time rate-of-change of velocity. The detail I was referring to (what Shinkansen operators are good at minimizing) is jerk, i.e. the time rate-of-change of acceleration. You can comfortably subject passengers to pretty high deceleration, provided you ramp up/down to/from that level in a gradual fashion. Conversely, even mild deceleration can create unpleasantly high instantaneous jerk values if that decel isn’t gradually tapered to zero as velocity also approaches zero. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [June 25, 2021, 3:33pm UTC](https://boards.straightdope.com/t/does-a-train-really-jerk-backwards-at-the-moment-that-it-comes-to-a-complete-stop/944705/36 "2021-06-25T15:33:24Z")
And trains used to have separate employees specifically called “brakemen”, before it was practical to directly control all the brakes from the front. ---
**Author:** ![Melbourne](https://avatars.discourse-cdn.com/v4/letter/m/b5e925/32.png) [@Melbourne](https://boards.straightdope.com/u/Melbourne)\ **Post date:** [June 25, 2021, 9:47pm UTC](https://boards.straightdope.com/t/does-a-train-really-jerk-backwards-at-the-moment-that-it-comes-to-a-complete-stop/944705/37 "2021-06-25T21:47:05Z")
> [@The\_Librarian](#): > > The locomotive rolling back a couple of inches is the delay in releasing the brakes and the elasticity of the train (after the whole train has stopped, the brakes are released (last car last) causing the locomotive to be “pulled back” by the last car: In 50 years as a rail commuter here, I have never seen a passenger carriage “pulled back”. ---
**Author:** ![Lucas\_Jackson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lucas_jackson/32/303_2.png) [@Lucas\_Jackson](https://boards.straightdope.com/u/Lucas_Jackson)\ **Post date:** [June 25, 2021, 10:33pm UTC](https://boards.straightdope.com/t/does-a-train-really-jerk-backwards-at-the-moment-that-it-comes-to-a-complete-stop/944705/38 "2021-06-25T22:33:11Z")
This thread reminds me… As kids we used to watch the old Ripcord TV series. For may years afterwards my friend refused to believe that skydivers didn’t go back upwards a bit after the 'chute inflates. The illusion, of course, being created because the cameraman continued to fall after the skydivers parachute deployed and slowed them. ---
**Author:** ![The\_Librarian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/the_librarian/32/402_2.png) [@The\_Librarian](https://boards.straightdope.com/u/The_Librarian)\ **Post date:** [June 26, 2021, 10:29am UTC](https://boards.straightdope.com/t/does-a-train-really-jerk-backwards-at-the-moment-that-it-comes-to-a-complete-stop/944705/39 "2021-06-26T10:29:20Z")
The “pulling back” I was responding to: > [@Mr\_Downtown](#): > > d stopped to watch a long train being slowly brought into the yard for servicing. I happened to be watching the locomotive wheels as it came to a stop and . . . saw a noticeable movement backwards as it came to a complete stop. My answer formulated differently: > [@Richard\_Pearse](#): > > There would be a very small amount of rearward movement due to various bits of the train compressing under breaking load and then returning to normal. ---
**Author:** ![Melbourne](https://avatars.discourse-cdn.com/v4/letter/m/b5e925/32.png) [@Melbourne](https://boards.straightdope.com/u/Melbourne)\ **Post date:** [June 27, 2021, 11:15pm UTC](https://boards.straightdope.com/t/does-a-train-really-jerk-backwards-at-the-moment-that-it-comes-to-a-complete-stop/944705/40 "2021-06-27T23:15:36Z")
The OP I was referring to: > [@hibernicus](#): > > standing passengers have to brace themselves [Previous page](https://boards.straightdope.com/t/does-a-train-really-jerk-backwards-at-the-moment-that-it-comes-to-a-complete-stop/944705.md?page=1) [Next page](https://boards.straightdope.com/t/does-a-train-really-jerk-backwards-at-the-moment-that-it-comes-to-a-complete-stop/944705.md?page=3)