
Slip Coaches: Back When British Express Trains Detached Passenger Cars at Speed - misnamed
https://99percentinvisible.org/article/slip-coaches-back-when-british-express-trains-detached-passenger-cars-at-speed/
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ljoshua
The flight path of landing planes is often directly over my home. How many
times I have wished during the final approach that I could hop in an personal
landing pod or sky dive out, landing in my driveway, than take the extra hour
or so that is required to deplane, get to transportation, and drive home...
Slip air travel anyone? :)

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jcl
Reminds me of Mad Jack Churchill, who in his later years would surprise fellow
passengers by throwing his briefcase out the train window -- ostensibly into
his backyard to avoid having to carry it home from the station.

[https://en.wikipedia.org/wiki/Jack_Churchill](https://en.wikipedia.org/wiki/Jack_Churchill)

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ascar
Churchill was said to be unhappy with the sudden end of the war, saying: "If
it wasn't for those damn Yanks, we could have kept the war going another 10
years!"

This made me laugh. His story is a really good read.

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pjc50
The Aramis PRT system of the 70s was intended to do this with individual or 4
seat cars, accelerating and decelerating to make trains. But the control
systems of the time weren't quite up to it.

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5DFractalTetris
...But could you match a platform to a slipcoach's velocity?

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cup-of-tea
I remember reading a proposal for a system where a high speed train would
travel non-stop for the entire length of its route. In halfway towns a shuttle
would be sent out to match the train's speed, interface with it to exchange
passengers then detach to return to the halfway town platform.

It sounds unbelievable, but remember it was once considered insane to consider
building a railway between Liverpool and Manchester.

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bobthepanda
The problem would be the scheduling. Even at the best of times railways rarely
run on the kind of precision that these kinds of operations would demand. Plus
it’d require a lot of duplicate railway since presumably it would take
distance for shuttles to accelerate and decelerate, and the shuttles would
need to get back to the original stations in time for the next trains.

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colejohnson66
> The problem would be the scheduling.

Not in Japan.

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myself248
I always figured the solution to this problem was buses. Take a bus and drive
it alongside the running train, then merge it sideways into a C-shaped train
car frame that accepts it and lifts it up. Now the bus is just another train
car. At another point along the route, it can be set down, and un-merge back
out again, and ply the streets again.

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victor106
They used to do this India till at least 15 years ago.

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Karupan
As an Indian who used to travel in trains quite a lot, this is news to me. Was
it only for particular routes? And sources I can read?

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victor106
[https://www.quora.com/What-is-a-link-express-train-in-
Indian...](https://www.quora.com/What-is-a-link-express-train-in-Indian-
Railways)

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fizzbuzzbazz2
Splitting for different destinations also seems useful. If one is to walk the
transfer time must be that of the slowest passengers. I lose 2 times 20 min
like that twice per day.

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cup-of-tea
Many trains in Europe split up and go in different directions. It's something
you have to be aware of so you don't end up on the wrong one.

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zimpenfish
Reasonably frequent for London trains heading to the coast (e.g. Brighton)

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tialaramex
The phrase in announcements for these trains will be e.g. "This train divides
at Southampton. Passengers for stations to Poole should be in the front 5 cars
of the train".

Because (as described below) these trains are actually constructed from
Multiple Units, the train can only be sub-divided if it in fact consists of
two or more smaller trains, for example 450s come in multiples of 4 so a 12
car train could divide into three. Some designs offset the driver's cab so
that a gangway for passengers fits through the "nose" of the train when it's
connected. In other designs you must leave the train and walk along a platform
to pass the point where the trains are joined.

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linker3000
On one UK journey from Portsmouth to Preston (Virgin Trains on Sundays), the
train would divide en route and the rear half continue to Preston and the
front half would go to Manchester.

One time, the conductor announced - several times during the first part of the
journey - that due to an electrical fault in the rear half of the train (no
lights), that part would go to the depot in Manchester, and the front would go
to Preston, so when the train stopped for splitting, please would everybody
swap carriages and make sure they were in the right half.

Needless to say, a few minutes after our section was on its way to Preston, a
few fretful discussions that included the phrase "...didn't you hear the
announcements?..." could be heard, followed by the odd expletive.

On another occasion, my train left London Victoria for (I think) Brighton,
Bognor Regis and Southampton Central (a double split to make 3 x 4 coach
trains), and the announcement went something like...

"This is the xxx train to Brighton, Bognor Regis and Southampton Central. Due
to a fault, this train is composed of 10 coaches instead of 12. This train
divides on route so please make sure you are in the correct part of the train;
the front 4 coaches will call at....the rear 4 coaches will call at....and the
middle 4...oh we've only got 10..oh, how are we going to do this...erm...hang
on I'll have to have a think about this...."

I don't recall the outcome!

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tialaramex
Southern has a bunch of different variants of class 377 in different lengths,
so presumably your 12 cars would have been 3 x 4 car length 377s.

Depending on what they had spare ("due to a fault") the 10 cars might have
consisted on 2 x 3 car plus 1 x 4 car, or of 2 x 5 car configurations.

In the latter case obviously the train can't split three ways, that's
impossible. I would expect that for your service they would choose to run the
train to Brighton, then split it and run half to Southampton Central, half to
Bognor.

To be fair this route actually could be served (albeit with a little delay) by
a single train, there's no huge divergence along the route to serve all of
them, it's mostly that it'd be a pain to get back out of Bognor heading for
Southampton, the signaller may not want to allow the relevant movement
(crossing from the up to the down side, or reversing on the down side) and the
driver may not be trained to do it even if a signaller will signal it.

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transfire
There is no reason this can't be done for modern rail systems. It would
greatly improve efficiency and time schedules. But alas, innovation in rail
has been very incremental (HyperLoop aside), and practically non-existent in
the States.

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jarfil
Rail systems shine when they can concentrate steering an power in more
efficient dedicated locomotives, with as many "dumb cars" as possible
"automatically" following them (thanks to the rails).

But in order to achieve higher granularity and better schedules, cars would
have to become more autonomous, which means duplicate steering systems and
lower efficiencies... unless there were no efficiency benefits in having a
dedicated locomotive, in which case it would make no sense to join cars
together in the first place.

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greglindahl
Dedicated locomotive? That's true for things like diesel freight trains, but
most high speed electric trains have motors in every car because electric
motors scale down just fine.

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cup-of-tea
Most, if not all, high speed trains operate as "train sets". They don't split
arbitrarily. Some like ICE use smaller sets that can join. Others, like
Eurostar, are fixed.

Some inner-city rail in Europe is like you describe but not anything high
speed (>~100mph) AFAIK.

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tialaramex
The technical term you're looking for is "multiple unit", and you're correct
that in a multiple unit it is not possible to arbitrarily couple together
arbitrary carriages, re-arranging the multiple unit is possible only at
dedicated maintenance facilities and may require a complete refit.

However everything else you've claimed is wrong. The designs you're talking
about DO have motors under many (or in some cases all) passenger coaches
driving the wheels, rather than a dedicated "locomotive" so they support your
parent's point, not yours.

The original Eurostar (class 373) trains are confusing because they're built
as multiple units but the lead and trailing cars basically just provide
traction, so the result looks a lot like a "conventional" locomotive plus
carriages. But modern Eurostar (class 374) looks exactly like any other
multiple unit and has motors distributed across the whole train.

Britain does operate a bunch of locomotive pulled high speed (125mph)
services, but it also owns a bunch of 125mph multiple units. Even the Desiro
444 and 450 trains could do 125mph if not for the fact they're configured
exclusively for third rail power limited to 100mph.

The reason none of those trains exceeds 125mph is purely down to legal/ safety
considerations. Britain uses coloured light signals with route control, as
speeds increase drivers struggle to correctly interpret and act on a light
signal by the side of the track. HS-1 (Eurostar) and many European high speed
services have in-cab signals, so the driver doesn't need to try to observe
fixed coloured light signals at the side of the track, the indications are
inside the cab with them.

As well as the reasons given earlier about improved performance from
distributing the traction power across the train, distributing the weight also
improves crash performance. Heavy locomotives will tend to crush a lightweight
passenger car, if we make all the cars of more similar weight this problem
goes away.

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cup-of-tea
> However everything else you've claimed is wrong.

Eh? I didn't say anything at all about where the motors were.

You're the second person in this thread to imagine me saying something wrong
and call me out on it.

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tialaramex
You wrote:

> Some inner-city rail in Europe is like you describe but not anything high
> speed (>~100mph) AFAIK.

That's referring to a post which claimed:

> most high speed electric trains have motors in every car because electric
> motors scale down just fine

The examples you gave were ICE and the Eurostar, which are groups rather than
specific classes of high speed train, but in both cases the modern classes
have motors in every car, they specifically _disprove_ your claim.

