Slip Coaches: Passenger Train Cars Detached at Speed

June 13, 2018 4:55 AM

For 100 years, express trains on British railways would sometimes drop passengers off at local stations without stopping, by detaching rear cars at speed while passing the station. Operation of these "slip coaches" (also called "slip carriages") required quite a bit of technical maneuvering, as Thomas and Friends could tell you. Slip coaches had their final day in 1960--and we have video from the voyage!
posted by duffell (31 comments total)

I appreciate the video poster's acute SEO skills by using the following as the sole text in the description of the video: "SLIPCOACH SLIPCOACHES Slip Coach Slip Coaches UK GWR Bicester 1960 detached coach last", and then filing the video in the "Pets and Animals" category. But that's just how I do my trainspotting.
posted by ardgedee at 5:06 AM on June 13, 2018 [32 favorites]

My dad used to try and do that with car passengers.
posted by arcticseal at 5:55 AM on June 13, 2018 [7 favorites]

This is real right, not like the burrito tunnel?

I've been hurt before
posted by shothotbot at 6:00 AM on June 13, 2018 [9 favorites]

I'm curious what gave rise to the slip coach process. It sounds like it expedites one thing (dropping off the people at station Y with minimal effect on the time for the rest of the carriage to reach station Z) at the cost of several other things (getting people from station Y to Z, keeping an entire train ready to pick up one coach for getting to station Z and beyond, the added trained staff and specialty equipment needed for the slip).

For this service to have survived for a century would have meant that, at one time, it was more efficient than maintaining separate local and express services, or else that it was an experiment that was so elaborate in implementation that nobody within the railway service dared dismantle it on fear of having to admit it was a bad idea and absorb the cost of replacing it.
posted by ardgedee at 6:42 AM on June 13, 2018 [8 favorites]

I wondered about that too, ardgeedee. The piece that's clearly missing is a way to bring the detached cars back up to speed to connect them to another moving train. Rockets, perhaps. Or a slingshot.
posted by qxntpqbbbqxl at 7:12 AM on June 13, 2018 [7 favorites]

it makes a lot of sense for highly directional service where rush hours are a real thing though, right? you can collect the slipped cars later, on a service-only or super-local train.

as a daily train rider, I have to say, this idea is just bonkers.
posted by Exceptional_Hubris at 7:37 AM on June 13, 2018 [5 favorites]

I love learning about something new to me! What a cool idea. The sound doesn't work on the the computer I am using now, so I watched the video with The Who playing in my head.
posted by TedW at 7:38 AM on June 13, 2018 [1 favorite]

Does Elon Musk know about this?
posted by fearfulsymmetry at 7:38 AM on June 13, 2018 [4 favorites]

Do. Not. Tell. Elon Musk!!!
posted by Katjusa Roquette at 7:40 AM on June 13, 2018 [22 favorites]

Nonono...you just save up the slipcoaches until you have a whole other train. Of course, you would have to have a sliptrain of nothing but engines go down the route first, dropping off engines...
posted by sexyrobot at 7:47 AM on June 13, 2018 [3 favorites]

The piece that's clearly missing is a way to bring the detached cars back up to speed to connect them to another moving train. Rockets, perhaps. Or a slingshot.

it makes a lot of sense for highly directional service where rush hours are a real thing though, right? you can collect the slipped cars later, on a service-only or super-local train.

Easy-peasy. Wait until rush hour the following morning, have folks board the slipped coaches a few minutes before the train comes back the other way, and then use a grappling hook system to join them back up at speed.
posted by Rock Steady at 7:48 AM on June 13, 2018 [3 favorites]

Or just build all the stations at the top of hills so the slip cars automatically slow down entering the station and speed up leaving. Although rockets are good too.
posted by TedW at 8:03 AM on June 13, 2018 [3 favorites]

I just realized I described the basic design of a rollercoaster.
posted by TedW at 8:04 AM on June 13, 2018 [14 favorites]

This also makes me wonder how often a slipped coach ran out of momentum short of the station. It can't have been an easy job for the operators, especially in bad weather or strong winds.
posted by ardgedee at 8:08 AM on June 13, 2018 [1 favorite]

That's why a brake's involved; they'd always slip when going faster then necessary. With practice, I can see 'em getting really good at estimating when -- a fun job. But I wouldn't enjoy traveling in a locked coach. Still --

Best of the Web -- what a zany idea! Thanks.
posted by Rash at 8:21 AM on June 13, 2018 [1 favorite]

It's not that far removed from a train that splits in two at a certain station, with the front half going on somewhere else and leaving the rest behind. Admittedly, doing it whilst standing at a platform is far less exciting, but the problem of what to do with the remaining carriages remains.
posted by fatfrank at 8:31 AM on June 13, 2018 [2 favorites]

TedW: the Central Line on the London Underground actually was built with each underground station at the top of a small incline. Climbing the incline helps slow arriving trains, and descending it helps accelerate departing trains.
posted by monotreme at 8:37 AM on June 13, 2018 [17 favorites]

This is cool. See also Bruno Latour's book about a failed French attempt to create autonomous trains.
posted by mecran01 at 8:47 AM on June 13, 2018 [2 favorites]

This seems fun. Does the UK have the equivalent of "heritage routes" or somebody that might allow somebody to experience this? Or maybe some crazy railway somewhere in the world is still doing it?
posted by LiteOpera at 9:00 AM on June 13, 2018 [1 favorite]

What if the slipped coach didn't brake, but just collided with the previous coach at the platform, giving that car most of the momentum needed to rejoin the train? You would need a little motor to compensate for the energy lost to friction, but that seems doable. I have an illustration here of the general principle. Sure, passengers might experience mild whiplash or death, but they'd get used to it.
posted by qxntpqbbbqxl at 9:05 AM on June 13, 2018 [4 favorites]

Sounds a bit like Buzz Aldrin's "Mars Cycler" -- a pickup and dropoff fuel-saving idea.
posted by hank at 9:10 AM on June 13, 2018

This is completely demented and I love it.
posted by Eyebrows McGee at 10:23 AM on June 13, 2018 [1 favorite]

I assume you have an express and several regular lines going outward at rush hour, so the express drops off cars, the regular lines come through and pick them up and take them to the terminus to be attached back to the express for rush hour back the other way the next morning/evening.
posted by tavella at 10:57 AM on June 13, 2018 [2 favorites]

Bicester is my home town. I've gone into London from that Station many times and used to live about 6 houses away from it. Later I lived about a quarter of a mile further down the line and as a kid used to play up on that line and get yelled at by the railway workers if we were caught.

The train stuff is cool, though.
posted by Brockles at 11:20 AM on June 13, 2018 [1 favorite]

Absolutely fascinating. Great post.
posted by 4ster at 12:00 PM on June 13, 2018

Man, fuck CGI Thomas.
posted by Chrysostom at 12:03 PM on June 13, 2018 [2 favorites]

monotreme: "TedW: the Central Line on the London Underground actually was built with each underground station at the top of a small incline. Climbing the incline helps slow arriving trains, and descending it helps accelerate departing trains."

This is a thing on the rail freight side, too. They're called humps. Sometimes you will see cars with delicate freight marked NO HUMPING.
posted by Chrysostom at 12:26 PM on June 13, 2018 [13 favorites]

Sure, passengers might experience mild whiplash or death, but they'd get used to it

Do you have VC funding yet?
posted by PMdixon at 2:30 PM on June 13, 2018 [5 favorites]

minor point of order. I believe the Victoria Line is built with humped stations, not the central line.

I'm quite interested in the idea of converting energy around instead of just boring old electricity.
So, old style brakes essentially just convert energy intoheat (which is why london clay is now hot, when once it was cold). Humped platforms convert kinetic energy into potential energy and back again.
Also, modern trains have regenerative braking, so you turn your kinetic energy into electric energy and you can reuse it.

In the same way in houses you can use heat pumps to move heat instead of generating new heat or phase change materials to convert heat into forming or breaking bonds.

I think the most interesting equation of all is old style tube trains turning coal into electricity, electricity into kinetic energy and tjen kinetic energy into heat. That heat going into the surrounding clay and then using aground source heat pump to heat your home by moving that heat from the clay where it's stored into your house where you want it.
posted by Just this guy, y'know at 2:45 AM on June 14, 2018 [1 favorite]

> Sure, passengers might experience mild whiplash or death, but they'd get used to it.

Do you have VC funding yet?

It's called ElasticCollisionCoin, and we'll be using the power of the blockchain to keep track of individual cars. (When shopping for ElasticCollisionCoin at cryptocoin exchanges, please ignore InElasticCollisionCoin. It's a malicious hard fork.)
posted by sebastienbailard at 1:34 PM on June 14, 2018 [6 favorites]

Sure, passengers might experience mild whiplash or death, but they'd get used to it

Mild death would still be preferable to Southern Rail.
posted by MattWPBS at 5:46 AM on June 15, 2018 [4 favorites]