Why did the UK not pursue double deck trains?

[bakerstreet]

I’m assuming this photo is genuine - apparently at London Charing Cross in the late 1940s.

Given some infrastructure on certain routes appears to have been able to cope at that time (bridges, tunnels etc) why do we not have these today?

 

[Bletchleyite]

Because doing double deck in the UK loading gauge produced something incredibly grim and cramped. It also didn't add much capacity - it was maybe 1.5x?

 

[AlterEgo]

Added less than 1.5x capacity, and we couldn’t have this design today for lots of reasons. We don’t have closed compartment stock for safety reasons, and that is very far from being accessible!

 

[zwk500]

The 4DD has a chequered history (and yes the photo is genuine). It wasn't really double-deck but as you can see from the photo a staggered arrangement. You'd have the upper passenger's feet between lower compartment's head height.
It didn't go anywhere because it was cramped, expensive to maintain and had low dwell times compared to a single deck train.

is a contemporary Pathe newsreel, and despite the optimistic tone, you can see the problems.

 

[Wilts Wanderer]

Because doing double deck in the UK loading gauge produced something incredibly grim and cramped. It also didn't add much capacity - it was maybe 1.5x?

It also massively slowed the service down, as the people upstairs could only exit their (cramped) compartments by squeezing through (equally cramped) downstairs compartments. Not ideal for the south of London commuter networks which needed to get on the move ASAP.

 

[dosxuk]

They fitted because they fitted in the same space as our current trains - and were a horrible cludge of a design even by contemporary standards. They only gave a modest increase in capacity over existing trains, at the expense of much longer dwell times and passenger comfort.

Nowadays, with modern stock where the majority of passengers are standing, there is simply no space for the squeezed in second deck.

 

[zwk500]

See also these other threads:

Could Double Deck trains be viable in the UK?

Not sure if I've started this thread in the right place but here goes:- What exactly is it that stops trains from being double deck in the UK? Are the bridges really too low for even "lowbridge" designs of DD carriages? or is it, like bendybuses, UK resistance to "strange foreign ideas"?

www.railforums.co.uk

My idea for double deck trains on the West Coast Main Line

Moderator note: this post was erroneously posted in https://www.railforums.co.uk/threads/government-announces-independent-review-into-hs2-programme.189492/page-25 ; we wish to remind members to please ensure speculative posts are posted in the Speculative Ideas section, thanks! :) I still feel...

www.railforums.co.uk

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

This is a point that my Dad keeps bringing up, which is why is it that any new UK trains orders are for longer trains rather than double deck trains as they have in Europe? I have explained to my Dad many times that I do not think that the UK rail infrastructure would be able to take double...

www.railforums.co.uk

 

[Wilts Wanderer]

The 4DD has a chequered history (and yes the photo is genuine). It wasn't really double-deck but as you can see from the photo a staggered arrangement. You'd have the upper passenger's feet between lower compartment's head height.
It didn't go anywhere because it was cramped, expensive to maintain and had low dwell times compared to a single deck train.

is a contemporary Pathe newsreel, and despite the optimistic tone, you can see the problems.

Fascinating piece of archive film. Imagine that crush-loaded, doesn’t bear thinking about. The poor standees downstairs would be amongst the knees of those on the stairs…

 

[Sorcerer]

Because a proper bilevel unit wouldn't fit within the UK's restrictive loading gauge, and the 1.5x increase in capacity is somewhat mitigated by the increased dwell times at stations which is especially unhelpful on some of the busiest routes in the country with high frequency as well as the reduced acceleration due to the increased weight of the train itself, both of which would require bigger gaps in the timetable. Double-decker trains might fill a small niche as we see across Europe, but for the UK it was never going to work. That's basically the whole answer to your question.

 

[75A]

If anyone is interested, 2 of the coaches have been preserved by the Bulleid 4DD group and are currently stored at Sellinge in Kent.

More information at: https://www.bulleid4dd.org.uk/

 

[LNW-GW Joint]

HS1 and HS2 could take double-deck designs as used on SNCF's LGVs, for stock that is captive to HS routes in the UK.
But for various reasons the procurers have gone with lighter single-deck designs.
In HS2's case it is because the trains need to run through on to classic NR infrastructure.

 

[Wilts Wanderer]

Double-decker trains might fill a small niche as we see across Europe, but for the UK it was never going to work.

Surely they don’t fit a small niche, hence why UK has never successfully introduced them

 

[zwk500]

HS1 and HS2 could take double-deck designs as used on SNCF's LGVs, for stock that is captive to HS routes in the UK.
But for various reasons the procurers have gone with lighter single-deck designs.
In HS2's case it is because the trains need to run through on to classic NR infrastructure.

AIUI All HS2 platforms will be built for UK-Sized trains so although they have the additional vertical clearances the trains won't be any wider in the lower part of the profile. Standard UIC Gauge trains thus won't fit even captive to HS2.

HS1 international platforms are built to the UIC profile so could have double-deck, but the domestic platforms are UK sized.

 

[bakerstreet]

Wow this sounds like a Heath Robinson concept. Thanks for the history. The image just appeared on a social media feed with no additional information.
I can see why these did not take off!

 

[Bletchleyite]

Wow this sounds like a Heath Robinson concept. Thanks for the history. The image just appeared on a social media feed with no additional information.
I can see why these did not take off!

Fundamentally the problem the UK has with double deckers is that our loading gauge gets quite narrow below solebar level. Most European and US double deckers gain the space by having the train quite wide well below our platform height. We also have less height to play with in general (even a normal double decker bus wouldn't fit).

It's curious how the UK is the reverse of mainland Europe with regard to road and rail - our standard road bridge height is higher than most of Europe uses (hence very high lorries and double decker buses) but our rail loading gauge is much smaller.

 

[Sorcerer]

Surely they don’t fit a small niche, hence why UK has never successfully introduced them

Touché.

 

[popeter45]

Because a proper bilevel unit wouldn't fit within the UK's restrictive loading gauge, and the 1.5x increase in capacity is somewhat mitigated by the increased dwell times at stations which is especially unhelpful on some of the busiest routes in the country with high frequency as well as the reduced acceleration due to the increased weight of the train itself, both of which would require bigger gaps in the timetable. Double-decker trains might fill a small niche as we see across Europe, but for the UK it was never going to work. That's basically the whole answer to your question.

also thats 1.5x of compartment seating
can prob get that 1.5x from open plan not to mention standing room

 

[The exile]

also thats 1.5x of compartment seating
can prob get that 1.5x from open plan not to mention standing room

Standing room yes; seating no. Non-corridor SUburban stock had a far higher seating capacity than open stock ever could.

 

[krus_aragon]

It's curious how the UK is the reverse of mainland Europe with regard to road and rail - our standard road bridge height is higher than most of Europe uses (hence very high lorries and double decker buses) but our rail loading gauge is much smaller.

One might argue that they're causal: if you've inherited a small railway loading gauge then there's a greater motivation to build your new motorways with larger clearance, and maybe even some futureproofing. If you've got a generous loading gauge already, then there's less ugency to over-engineer your roads.

 

[edwin_m]

Fundamentally the problem the UK has with double deckers is that our loading gauge gets quite narrow below solebar level. Most European and US double deckers gain the space by having the train quite wide well below our platform height. We also have less height to play with in general (even a normal double decker bus wouldn't fit).

It's curious how the UK is the reverse of mainland Europe with regard to road and rail - our standard road bridge height is higher than most of Europe uses (hence very high lorries and double decker buses) but our rail loading gauge is much smaller.

British Rail Research looked into double deck trains within the UK loading gauge, 70s or 80s I think - before my time there but someone who later became my manager was involved with it. I believe it was longitudinal seating down near track level, which would have been very cramped because of the narrowing of the gauge below platform height, and more normal transverse seats on the upper deck but with quite limited headroom.

A standard for bridge clearances over roads probably only became a thing with the appearance of modern dual carriageways and motorways which needed lots of bridges. Urban roads had far fewer bridges over, mainly railways, often low enough to limit buses to low-height designs or single deck. Despite this, the double deck bus became common in Britain and in very few other countries, and may well account for the extra bridge clearance allowed in our roadbuilding from about the 1950s onwards. I don't think extra height for lorries was a factor in that decision, because they didn't appear until much later.

 

[The exile]

One might argue that they're causal: if you've inherited a small railway loading gauge then there's a greater motivation to build your new motorways with larger clearance, and maybe even some futureproofing. If you've got a generous loading gauge already, then there's less ugency to over-engineer your roads.

Not to mention the fact that whereas we pioneered railway engineering, we were pretty late to the motorway party.

 

[6Gman]

Bulleid.

Noted for innovation, but rarely for practicality!

 

[zwk500]

British Rail Research looked into double deck trains within the UK loading gauge, 70s or 80s I think - before my time there but someone who later became my manager was involved with it. I believe it was longitudinal seating down near track level, which would have been very cramped because of the narrowing of the gauge below platform height, and more normal transverse seats on the upper deck but with quite limited headroom.

To underline this point, see this image:

(https://qph.cf2.quoracdn.net/main-qimg-7b72ecbe1b96a6ada5b74df337bd434f)

Image of UIC loading gauge profiles compared to a typical British platform and Loading Gauge

The lime green profile is W6, which is a good approximation of the standard carriage profile. you can see that it is noticeably narrower below the platform, because of how close to the rail it is. You can also see the problem with the headroom quite clearly.

 

[Gloster]

Bulleid.

Noted for innovation, but rarely for practicality!

Somewhere I read that Bulleid was an ideal deputy to a chief who wanted to take a broad view of the whole CME’s department and design, which was roughly the situation on the LNER. Bulleid was able to experiment and come up with innovative ideas, while Gresley was able to look at them and, when necessary, say, “That is an interesting idea, but…” Once he was on the Southern there was nobody except the board to haul back on the reins.

 

[stuving]

Paul Maynard MP (then junior transport minister for rail) answered a written commons question about this subject (increasing capacity in general and and using DD trains in particular) on 22 November 2016:

The Department commissioned in 2007 a study by Network Rail into the use of double-decked trains which can be found at Preliminary Evaluation of Double Deck & Extra Long Train Operations. The outcome of the report found that it would not be economic to introduce double decker trains on the existing rail network.

In 2010 the Department commissioned a study by Atkins into alternatives to the building of HS2 which considered the use of double decked trains on West Coast and Midland main lines which can be found at High Speed 2 Strategic Alternatives Study Rail Interventions Report, the conclusion in respect of double decker trains rejected the idea because it was significantly more expensive and disruptive.

Network Rail have also undertaken a study to look at the potential use of double-decked trains on the Wessex Route for services into Waterloo. Details can be found at http://www.networkrail.co.uk/long-term-planning-process/Wessex-route-study/.

This first document is the most relevant to this thread, as it is a reasonably thorough feasibility study. Its main conclusion is:

The conclusion of this analysis, combined with the overall structure of the analysis vehicles, effectively confirmed that a vehicle fitting within the existing overall static height of 3990mm would not provide acceptable headroom. This conclusion also addresses the objective to improve the passenger experience and provide for a population that is taller than it has been historically and forecast to have an increasing body mass index.

The adoption of an existing European profile train is considered uneconomic because of the extensive infrastructure work required to accommodate the longer bogie centres with the resulting implications for end throw and mid throw. Work would also be required to the platforms to suit their highly efficient end vestibule arrangements and hence release width for the lower deck. These alterations would be further complicated by the need to continue to support the use of the existing rolling stock. One feature, seen in some European stock, that would be beneficial is the through connection at the high level, but was not assessed in this report.

The second does not consider DD trains, it just reports that previous studies rejected the ideas as impractical. The third link no longer works, but it must be the 2015 Wessex Route Study. I have a draft copy of that, and this is the final version (substantially rewritten).

The Wessex route option proposed was for double deck trains too big for the existing gauge to run Basingstoke-Waterloo only, with infrastructure work to allow them to fit. An interesting idea, of which NR concluded:

Network Rail is continuing to undertake development work to understand the scale of network investment required to operate double-deck trains on the SWML to Basingstoke. Initial conclusions, however, indicate that this is likely to be a poor value-for-money solution.

I find it odd that they are so positive.

 

[WesternLancer]

If anyone is interested, 2 of the coaches have been preserved by the Bulleid 4DD group and are currently stored at Sellinge in Kent.

More information at: https://www.bulleid4dd.org.uk/

Yes. Would be good to see them restored so you could go inside and experience the design!

 

[Gloster]

Paul Maynard MP (then junior transport minister for rail) answered a written commons question about this subject (increasing capacity in general and and using DD trains in particular) on 22 November 2016:

This first document is the most relevant to this thread, as it is a reasonably thorough feasibility study. Its main conclusion is:


The second does not consider DD trains, it just reports that previous studies rejected the ideas as impractical. The third link no longer works, but it must be the 2015 Wessex Route Study. I have a draft copy of that, and this is the final version (substantially rewritten).

The Wessex route option proposed was for double deck trains too big for the existing gauge to run Basingstoke-Waterloo only, with infrastructure work to allow them to fit. An interesting idea, of which NR concluded:

I find it odd that they are so positive.

Well, for a start, end and side overhang would mean that you would have to either widen the Waterloo-Clapham Junction section or lose a line. You would instantly lose more than you would gain.

 

[ge-gn]

Yes. Would be good to see them restored so you could go inside and experience the design!

I seem to recall there is one of these at the East Anglia Transport Museum in Lowestoft, which you can go inside. It is cramped indeed!

 

[edwin_m]

The Wessex route option proposed was for double deck trains too big for the existing gauge to run Basingstoke-Waterloo only, with infrastructure work to allow them to fit. An interesting idea, of which NR concluded:

Presumably all other trains on this section would have to run non-stop because platforms would need to be set back to clear the wider trains, resulting in a dangerous platform gap for narrower ones.

 

[zwk500]

Presumably all other trains on this section would have to run non-stop because platforms would need to be set back to clear the wider trains, resulting in a dangerous platform gap for narrower ones.

Or they'd be confined to the Slow lines, with standard platforms on the fast lines.