Slip Coaches: Back When British Express Trains Detached Passenger Cars at Speed | Hacker News Reader

Slip Coaches: Back When British Express Trains Detached Passenger Cars at Speed

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176 pointsmisnamed68 comments

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? :)

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

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.

My dad told me about my grandfather, who I never knew, who would pull the emergency cable at the end of his garden and be ready with the fine in his hand, before walking to his house.

Thank you for this. I actually had never heard of this guy and my evening is richer now having read about him!

any discussion, regardless of topic, is improved by referencing mad jack.

Taking intercity bus from Boston to NYC, I've many times been fully stopped in Connecticut rush-hour traffic, and looked longingly out the window at an oh-so-close commuter rail station, with trains rumbling away, fast and empty. Or later, stopped at a red light in the city, mused that by getting off now, I'd shave an hour off my travel time. In India, in much of the world, one could just go for it. I often forget to notice the severe systemic inefficiencies of everyday life.

Not intercity, but for a time london's routemaster buses made this sort of thing possible. Alas, no more. https://metro.co.uk/2016/09/02/you-can-no-longer-hop-on-hop-...

Why not take the train?

The BOS-NYC Amtrak route costs a significant multiple of the buses (2-3x fares of the reputable bus companies, depending on day+time). On average, it takes about the same amount of time -- the bus is just higher variance.

The train that mncharity refers to is the much more reasonably priced NYC commuter rail, which does not reach Boston.

If you book at least 2 weeks out and travel off-peak you can get the Amtrak trip for about $50. Otherwise it’s $70-100.

Ignoring the costs, I find the quality of life on the train to be far superior. No traffic, you can walk around, there are power outlets and the seats are pretty big.

For me, being able to work for 4.5 hours vs feeling carsick on a bus for similar or more time (I get nausea very easily when other people drive me), it was always worth it.

The other thing I would do is drive the car to an MTA stop and garage it for a couple of days while I took the commuter rail into town. Which option I took depended on ticket prices and the length of time I was staying.

Could he take a bus to the edge of New York's railway network, then change to a train? I did roughly that to get from Hartford to New York once - got to New Haven by car, then got a Metro-North train into town. So, train to Providence, bus to New Haven (a bit over two hours), train to New York? It does seem like quite a trip.

Somebody is working on "escapable" capsules inside planes, though for the purpose of surviving a plane crash. Maybe they could extend it to grant you your wish at some point ;-)

That doesn't seem like a very worthwhile endeavor. Most plane crashes occur on landing or just after takeoff, there would be no time to get into an escape pod.

The plane should be comprised of a series of these pods, each of them as a single unit with a few passengers. Then upon unavoidable crash they can be "released" with explosive parachutes, hoping for the best.

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.

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

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.

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.

> The problem would be the scheduling.

Not in Japan.

This one?

https://www.theatlantic.com/china/archive/2013/12/this-propo...

On most rail routes in Austria we have high speed trains and low speed trains on the same routes. When you need to go to a smaller station, you get off at the closest major station and switch to the slow train. It would be awesome if you could just switch directly to the low speed train whenever the high speed train passed it... (Then you don't even need to have shuttles going back and forth)

This would be awesome.

Seems extremely cost prohibitive. In addition to the extra rails and control systems, you’d need a high speed locomotive and several cars for every single station along the route.

In theory it could work. I think one big problem would be the erosion of the rails, slowly drifting apart.

You could just link all four rails to prevent that.

It would also be tricky because you'd have to get everyone transferred in time. Those stretches would have to be pretty long.

Reminds me of the moving platform idea a few years back. Essentially, platform trains would run on a loop, connecting to high speed express trains. It sounded unsafe, but maybe not more dangerous than a slip coach.

https://io9.gizmodo.com/5863484/moving-platforms-let-you-get...

Your question makes me think of how some airplanes refuel in flight, which blows my mind.

Sure, at zero :)

And I'm reminded of the various whip devices in Stephenson's Seveneves.

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.

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

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?

https://www.quora.com/What-is-a-link-express-train-in-Indian...

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.

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.

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

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.

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!

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.

In the Netherlands we have trains with the cab above the passenger compartiment[1][2] but the national rail service has recently revised these and welded shut the passenger walk-through coupling due to maintenance costs and frequent breakdowns of the many moving parts.

[1] photo: https://upload.wikimedia.org/wikipedia/commons/thumb/c/cf/NS...

[2] video of the walk-through coupler: https://www.youtube.com/watch?v=mIi2CDYG7jc

I was on a sleeper train a few years ago that would detach cars as it went along.

The Scottish sleepers detach en route, you leave London and some coaches go to Fort William, some to Inverness, some to Aberdeen.

The later train does Edinburgh and Glasgow.

One of the few (only?) loco hauled splits in tr UK. DMU and EMU splits are very common - both ones where half the train terminates short (e.g. London to Birmingham via Northampton, or London to Holyhead via Chester), or they go to different locations.

I'm not sure about the specifics, but it would drop cars in the station on the route. It was from Amsterdam to Prague via Berlin. This was back in 2013, so I'm not sure if things have changed.

The effect of the northern Scotland sleeper splitting, but being pulled by a locomotive, is the train reverses at Glasgow.

I found I woke travelling in the opposite direction, with the sun streaming through the now East-facing window.

I think it depends on the day, sometimes th train runs via the west coast, sometimes via the east coast

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.

Uh, electric train cars are all but self propelled, and could carry their own electricity if so desired.

Trollies and street cars are individually powered.

Slip cars only made sense during the age of steam power, when locomotive power was supplied by huge coal powered engines with furnaces, before internal combustion and deisel made smaller power plants possible.

It's interesting, but now we have monorails, magnetic levetation, induction and more, and the concept of coasting to a halt at a precise point pretty much only has utility in amusement parks.

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.

Modern passenger trains have motors spread throughout the entire train. It allows them to accelerate better than is possible with a dedicated power car. This is because multiple wheels have more contact with the track. Modern diesel trains have multiple smaller generators spread throughout the train rather than dedicated power cars. Both these approaches give better modularity as the power availabile scales with the length of a train.

The efficiency gain in splitting trains is mostly related to reducing the number of drivers needed. It also reduces the demand on track and platforms that may be congested. Both these things could be solved through better automation. Have the train driven by a computer and automate signalling to allow trains to run closer together.

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.

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.

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.

> 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.

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.

My understanding is that freight trains use electric motors as well. The diesel engine acts as an electric generator rather than being connected directly to the drivetrain.

No engines have an internal combustion engine connected directly to the wheels. You can't get anywhere near enough torque. Steam engines have incredible torque. What you're describing is a diesel-electric and is essentially synonymous with saying diesel engine on the railway.

There are also electro-diesels which can shut off their diesel engine and take electricity directly from an overhead line or third rail by raising a pantograph or lowering a boot. This used to happen at Faringdon in London (maybe still does).

There are non-trivial numbers of diesel-mechanical (IC to wheels via a gearbox) and diesel-hydraulic (IC to wheels via a fluid coupling) trains out there. The British class 172 Turbostar is an example of the former, most other class 1xx DMUs the latter.

Diesel electric transmission does happen on smaller multiple units sometimes, but really shines on larger and faster trains, or on electro-diesels (where you need the electric final drive anyway).

Doubt Farringdon switched from diesel to overhead - overhead to third rail. Some trains have to stop to raise the pantograph, some do it on the fly (I think the 395s can switch 3rd rail to ohel at 60mph when coming on/off hs1)

Some trains are hybrid - will use electricity while under wires, and switch to diesel when there's no wires, the new class 800 in the UK as an example.

It was diesel to overhead. It was the Thameslink train and I think it used diesel south of London (to Brighton).

When the snow hill tunnel re-opened in 1988, and trains started from Farringdon to Blackfriars, they were operated by class 319s, which were dual voltage from the very start. While I'm sure some diesel engineering trains have been through the tunnels, and perhaps some diesel goods trains in the 60s before the closure, I'm not aware of any diesel passenger trains through them (as there were no passenger trains since 1916)

Some 319s are being converted to partial diesel and becoming class 769s, but not on this route.

Oh it could have been switching from overhead to third rail... I never actually went on the train to Brighton, I just remember the pantograph coming down.

Still does it now, there's a similar switchover north of Shepherds Bush. The Southern 350s used to stop when I got that train, I think the overground trains can raise/lower on the fly. I assume there's a similar changeover in East London.

Before 2009 and HS1 to St Pancras, Eurostar also switched from overhead to third rail, on the fly I think, somewhere near Ashford.

You're completely wrong. Most diesel locomotives are in fact diesel electrics. I.e. diesel engine, generator, electric motors. Most of those cannot use external power sources (although a few can, e.g. class 73 in the UK).

Certainly in the UK: the most common locomotives such as class 66, 60, 58, 67, 47 - they're all diesel electric.

In the US, same story: for passengers the GE Genesis is pretty big, things like SD90MAC and AC6000CW are big for freight.

I think you misread my comment.

I'm loving how nobody has called out the fact that this comment pretends trains have "steering systems" and need to "concentrate steering" in locomotives.

I hate to "well actually"...but some loco's do actually have steerable bogies (or trucks). The class 66 is an example of such a loco which permits it to go pretty much anywhere on the UK rail network where the track would previously only allow lighter and less powerful engines.

https://www.youtube.com/watch?v=2OGRwD-00b8

https://patents.google.com/patent/US20030230213

Not sure if this is what jarfil meant by "steering".

https://en.wikipedia.org/wiki/Point_machine

It would be kind of tedious to go into great detail. Feels like nerd sniping.

What's going on with hyperloop these days?

Reply on news.ycombinator.com