Why can't future train orders be for double deck trains?

[mike57]

That's magnificent! I don't suppose there's any chance you've got one showing C1, W12 and UIC GB? Would be interesting to have a visual representation of what we'd need for something like the French or German DD trains on our network

I could probably produce one, if I can find some suitable graphics, I created that one by dropping them onto a scaled sheet in Visio, and streched the graphics until the dimensions shown match the scale dimension. I then used transpancy settings to overlay the graphics. It not perfect but gives a good visual representation of the issues. I'll have a play after work

 

[MarkyT]

Your comment got me looking into it, after a bit of googling I managed to find two images which I have managed to superimpose to the same scale, its not 100% accurate, but shows the problem we have in the UK, we cant go out or up.

Red is UK C1, Blue is pre 1987 Japanese 3'6", Grey is post 1987 Japanese, and green is Japanese 4'8" high speed. current Japanese loading gauge is bigger all round, earlier one (which still applies on some line as far as I can work out) is very similar to UK, except the bottom quarter, which as you say is a lot more generous

View attachment 99676

That's a brilliant superimposition showing the similarity of Japan's narrow gauge profile to that of the UK's standard gauge trains. Many people are aware of the double decker Shinkansen trains which clearly fit within the much bigger green profile, but are currently being phased out. Japan also has some bi-level narrow gauge rolling stock. It's rarely complete trains however, mostly a handful of 'green' (1st) class cars within otherwise standard class single deck outer suburban EMUs, working longer distance limited expresses into Tokyo. There were also some double decker sleeping car trains on the narrow gauge, although I think all of these have been discontinued with the steady growth of the Shinkansen. Some of their rolling stock has found a new use in various luxury cruise trains that tour the nation.

 

[Bald Rick]

That's magnificent! I don't suppose there's any chance you've got one showing C1, W12 and UIC GB? Would be interesting to have a visual representation of what we'd need for something like the French or German DD trains on our network

Various places have it, but here is one example. W12 is the black box.

 

[zwk500]

Various places have it, but here is one example. W12 is the black box.

Much obliged.

 

[mike57]

Here is C1 superimposed:

 

[AM9]

View attachment 99749

Here is C1 superimposed:

Although this is the umpteenth thread where the DD question as been explained, they still keep coming. The fact is that height isn't the main limitation of the modern UK network, and dealing with that need not be as prohibitively expensive as is often assumed. On many lines when they are electrified, adjustments to overbridge clearance have been made when what is Victorian infrastructure needs replacing for road reasons or just that they are life-expired. For a few decades now, their replacement structures have normally been built with sufficient clearance for normal height OLE which at 4.77m would in itself allow up to GB+ to pass under, and with some of the modern techniques for Reduced and Special Reduced clearance installations could be configured to allow GB+ electric stock to operate there. Tunnels are a different proposition but even they need major refurbishment or reboring such as for W12 clearance and the Farnworth tunnel shows just what can be achieved. Above floor width wise, although less than the 3.15m of UIC stock, 2.82m is no problem for 2+2 seating so it wouldn't be any more a problem on two decks, but....
the real killer is the below floor width where the maximum external width is 2.59m. Any sensible design of DD stock would need to have at least 2+2 seating in the lower deck and that limit just couldn't deliver it. To fix that is much more difficult, - platform edges could be moved back in many cases but the proliferation of girder truss underbridges would be extremely expensive and disruptive (read that as even more expensive) to deal with, especially on the 3rd rail routes out of London where for many miles across south London, tracks run on raised formations with road underbridges every few hundred metres.
One other issue is that DD stock may provide slightly more seating capacity per metre of train length (but not much after underfloor equipment has been relocated and accessibilty modifications made for split levels), but on a busy line (as others have explained) dwell times would need to be extended, which can result in lower total line or route capacity, making the whole expensive exercise completely pointless.

 

[The exile]

In respect of loading times, I seem to remember that when the Munich S-Bahn started to reach capacity (both in terms of full trains and number of trains through the tunnel), DB briefly borrowed some DD stock (shows how long ago this was) and trialled it. Didn’t take long to realise it cut capacity - partly through slower acceleration ( Ok irrelevant to this discussion) but also due to load times. Loading times were also a problem on the RE1 through the Ruhr in peak times. Where they work well is increasing capacity on medium use lines with chronically short platforms!

 

[Emyr]

Given a fixed formation of 2-4 cars, and the need for some single-deck space for accessibility, buggies, bicycles and toilets, how much underfloor equipment does an EMU need? I assume the increase in density of power electronics is balanced by an increase in performance requirements. Can we make some guestimates by comparing EMU and bi-mode versions of the same family?

 

[AM9]

Given a fixed formation of 2-4 cars, and the need for some single-deck space for accessibility, buggies, bicycles and toilets, how much underfloor equipment does an EMU need? I assume the increase in density of power electronics is balanced by an increase in performance requirements. Can we make some guestimates by comparing EMU and bi-mode versions of the same family?

Well, any multiple unit requires auxiliary power arrangements for hotel services, compressors and storage cylinders for brakes, toilet retention tanks, then for diesel-electric/bi-mode units there's the diesel engines, generators, traction electronics, switchgear, fuel tanks, transformer. For a BEMU, there's the small issue of the batteries which might take a similar space to the gensets. I would say that lot would occupy about half of a car in a four-car set. So capacity would already be 12% down on above floor length.
Above floor level there's also the need for stairs up and down from the entrance vestibules and end car crumple zones (on both decks), so it's easy to see that there's very little gain but a lot of operational disadvantages, and that's ignoring the hefty cost of route clearance.

 

[miklcct]

Because it will increase dwell time at stations, making the line congested.

 

[Jozhua]

Double decker trains are a bit of a red herring. I see their primary uses on super long distance and sleeper services, where loading times are less important and having some extra space is a plus.

For commuter service, they can end up causing more accessibility issues and longer dwell times.

New alignments are being built to a more standard loading gauge, but for now, double deckers are just impractical considering the cost of adapting the infrastructure, which could go towards improved frequency or just longer trains.

Japan have double decker trains on their classic lines, but how does their loading gauge compare with ours (yes I know track gauge is 3ft 6in)

I remember looking this up a while ago - Japanese loading gauge is actually still bigger on the narrow gauge network lol.

 

[AM9]

Double decker trains are a bit of a red herring. I see their primary uses on super long distance and sleeper services, where loading times are less important and having some extra space is a plus.

For commuter service, they can end up causing more accessibility issues and longer dwell times.

New alignments are being built to a more standard loading gauge, but for now, double deckers are just impractical considering the cost of adapting the infrastructure, which could go towards improved frequency or just longer trains.

I remember looking this up a while ago - Japanese loading gauge is actually still bigger on the narrow gauge network lol.

It is wider especially in the critical below solebar area.

 

[MarkyT]

For commuter service, they can end up causing more accessibility issues and longer dwell times.

I think that's why in general Japanese railways only use bi-level 'green cars' in their suburban limited express rakes. Green car is equivalent to European first class, so density is lower than standard class. I assume they've calculated that the lower number of premium 'green' passengers should not add to dwell time significantly and the limited expresses obviously have only limited stops en route anyway.

I remember looking this up a while ago - Japanese loading gauge is actually still bigger on the narrow gauge network lol.

A Scottish engineer was heavily involved with setting up the first railways in Japan when the country started opening up to the west I recall. Scottish lines have some of the most generous structure gauges for railways in the UK, whereas our C1 is the 'go anywhere' profile which is limited by the worst-case throughout the UK, probably in the south-east of England somewhere (clearly the Hastings line was a special outlier case with its special narrow rolling stock before the offending tunnels were singled).

 

[WideRanger]

I think that's why in general Japanese railways only use bi-level 'green cars' in their suburban limited express rakes. Green car is equivalent to European first class, so density is lower than standard class. I assume they've calculated that the lower number of premium 'green' passengers should not add to dwell time significantly and the limited expresses obviously have only limited stops en route anyway.
View attachment 99836

A Scottish engineer was heavily involved with setting up the first railways in Japan when the country started opening up to the west I recall. Scottish lines have some of the most generous structure gauges for railways in the UK, whereas our C1 is the 'go anywhere' profile which is limited by the worst-case throughout the UK, probably in the south-east of England somewhere (clearly the Hastings line was a special outlier case with its special narrow rolling stock before the offending tunnels were singled).

In the train shown, there are 2 bi-level cars, in a rake of 15. Those 2 cars don't have motored bogies, or pantographs. Unlike the rest of the train, each of the cars has only 2 single-leaf doors (because as @MarkyT says, there is not expected to be as many people going in or out because the people riding in those cars are often on the train for an hour or more - which is why they are willing to play the supplement to ride in those cars). More importantly, those cars are not for standing.

So, even on a normal Japanese train, they only have a few cars of bilevel at most, in order to maximise standing space, and to allow for pantographs and motors.

 

[Jozhua]

While double deckers don't make sense for the UK, considering the extra cost, I think there is absolutely space for the use of double-decking on longer distance/limited stop services in other countries, or indeed on some of our high speed services.

Sleepers for example have lower density seating due to the requirement for extra space to sleep - if double decking those is an option, it would be hard to find a reason not to do it! If we started to run sleeper services to areas of Europe - I can imagine Spain would be a fantastic place to run sleeper trains to - then having those be double deck would make a ton of sense! On Amtrak's long distance routes outside of the North East corridor, they also make quite a lot of sense. Heck, even GO Transit limited express services in Toronto are probably quite suited to double decks (but local services maybe not lol)...

RM transit has a pretty good video on the double-deck conundrum, where it is/isn't appropriate.