Double deck trains - again ...

[HSTEd]

British trains are already arguably too cramped to be truly attractive in the modern era. Just look at the number of people who stick into the aisle in standard class these days, even on 2+2!

The low ceilings would make it positively unpleasant.

 

[Trainbike46]

BR W6 is 3.965m above rail level, UIC GA/GB/GB+ is 4.320m above Rail level. It's not impossible that with a very low floor and accepting low-ish ceiling heights of 2m-1.8m you could fit 2 full decks in the UK. It wouldn't be worth it at all but that's a different kettle of fish.

you couldn't fit 2 2m decks in 3.965m for obvious reasons.

The minimum acceptable ceiling height would be somewhere between 2sigma and 3sigma above the average men's height. If using 2sigma, about 2.5% of men wouldn't be able to stand upright. If using 3sigma this decreases to 0.15%*.

For the UK this means, with a mean of 175.9 cm in 2021, and an estimated standard deviation of 6-8 cm (which I'm taking as 7 cm), that gives a 2sigma level of 189.9 cm and a 3sigma level of 196.9 cm. You then need to add the allowances for the dynamic envelope of walking on top of that.

If you want to even slightly futureproof your new trains (and you should, as they'll last ~40 years), you use the average height of 16-24yo men instead, which is 178.8, which gives 192.8 cm for 2sigma, and 199.8 cm for 3sigma, and once again the allowances for the dynamic envelope of walking should be added on top of that.

While the final numbers chosen will depend on what the acceptable number of people hitting their head is, it seems unlike anything less than 2m would be a terrible idea. However, even using the 2sigma numbers, no future proofing, and no allowance for the dynamic envelope of walking the minimum comes to 190cm, and even that only gives you a total of 16.5 cm for everything between the railhead and the top of the loading gauge that isn't passenger space. It simply cannot be made to fit. Of course, back in the real world, where the minimum height for passenger space really should be at least 2m (and ideally more), it most certainly can't fit.

*assuming height within a gender approximately follows a normal distribution, according to the 3sigma rule. This is half the values lying more than 2/3sigma from the mean, as the other half of those values would be expected to be at the low end. Using men's height as women are, in the UK, on average shorter.

 

[Sorcerer]

Upstairs you'd fit in 2+2. The narrow part of the UK loading gauge is below platform level where it'd have to be 2+1. But the problem is height.

I would've thought that 2+2 on the top deck wouldn't be possible based on the AeroLiner's profile. Even with a lower flower for the +1 part of the seating it was cramped. But if we can only have 2+1 seating downstairs as well then I'm inclined to say any capacity would be well below a 50% increase like we would see on a Euroduplex (which are loco-hauled as well so don't even have the added traction motors that an EMU would).

 

[swt_passenger]

I would've thought that 2+2 on the top deck wouldn't be possible based on the AeroLiner's profile. Even with a lower flower for the +1 part of the seating it was cramped. But if we can only have 2+1 seating downstairs as well then I'm inclined to say any capacity would be well below a 50% increase like we would see on a Euroduplex (which are loco-hauled as well so don't even have the added traction motors that an EMU would).

The DfT report (attached earlier) reckoned about only a 25% max seating gain in our normal loading gauge.

 

[Sorcerer]

The DfT report (attached earlier) reckoned about only a 25% max seating gain in our normal loading gauge.

Not quite terrible but definitely not worth the increased dwell times and reduced line capacity, and especially not worth the horribly cramped conditions for passengers. You'd probably have more space stowing away in the cargo hold of a plane (still wouldn't recommend it for obvious reasons of course).

 

[joieman]

British trains are already arguably too cramped to be truly attractive in the modern era. Just look at the number of people who stick into the aisle in standard class these days, even on 2+2!

The low ceilings would make it positively unpleasant.

Theoretically, having double-decker trains would mean more seats, which therefore would mean fewer people standing. And if a person is seated, then height wouldn't matter quite so much. But boarding and alighting would still be less than ideal. Big hombre me already has to deal with shorter ceilings on double-decker buses, although I don't really think about it once I've sat down. But people aren't supposed to stand upstairs on buses; I don't think that kind of restriction would apply to trains, but standees would be less than happy!

 

[Mikey C]

Does anyone stand upstairs on European double deckers anyway? I can't remember whether I needed to stoop slightly to walk through the train or not on my last experience (the photo is from upstairs on a Belgian double decker) but I can't imagine anyone standing there instead of the open area by the doors.

 

[supervc-10]

I remember stooping to clamber to seats on the upper deck of the METRA Electric in Chicago. We went upstairs for the novelty, the locals were avoiding it.

Interior panorama of an upper-deck Metra commuter train car between Winnetka and Chicago, Illinois Stock Photo - Alamy

Download this stock image: Interior panorama of an upper-deck Metra commuter train car between Winnetka and Chicago, Illinois - T0BWEB from Alamy's library of millions of high resolution stock photos, illustrations and vectors.

www.alamy.com

They are very odd, with inwards facing tip down seats and the upper deck kind of runs as a mezzanine around the car. The photo linked above is the best way to explain it.

Highliner - Wikipedia

en.wikipedia.org

They are odd vehicles to be sure. The overall height is 4.8 m according to Wiki, so far beyond the UK loading gauge, but the lower sections of floor are actually *above* the bogies, not dropping down between them.

 

[HSTEd]

I remember stooping to clamber to seats on the upper deck of the METRA Electric in Chicago. We went upstairs for the novelty, the locals were avoiding it.

Interior panorama of an upper-deck Metra commuter train car between Winnetka and Chicago, Illinois Stock Photo - Alamy

Download this stock image: Interior panorama of an upper-deck Metra commuter train car between Winnetka and Chicago, Illinois - T0BWEB from Alamy's library of millions of high resolution stock photos, illustrations and vectors.

www.alamy.com

They are very odd, with inwards facing tip down seats and the upper deck kind of runs as a mezzanine around the car. The photo linked above is the best way to explain it.

Highliner - Wikipedia

en.wikipedia.org

They are odd vehicles to be sure. The overall height is 4.8 m according to Wiki, so far beyond the UK loading gauge, but the lower sections of floor are actually *above* the bogies, not dropping down between them.

My understanding with these is that the "gallery" is provided to allow a single staff member to check tickets on both levels with a single pass through the vehicle.

It always seemed, from pictures, to destroy the advantage of double decks because there really aren't many seats upstairs. But some operators do continue to use them, so perhaps they work quite well in practice.

The 2nd generation Superliner derived 'Surfliner' vehicles used on the eponymous Pacific Surfliner have ~89 seats, but they appear rather generous in terms of internal space and facilities (one disabled and one compact toilet per vehicle).

But then again, they are absolutely enormous in height terms, albeit not particularly so in width.

 

[DelW]

The 2nd generation Superliner derived 'Surfliner' vehicles used on the eponymous Pacific Surfliner have ~89 seats, but they appear rather generous in terms of internal space and facilities (one disabled and one compact toilet per vehicle).

But then again, they are absolutely enormous in height terms, albeit not particularly so in width.

I'd say very generous ....

Admittedly this is business class (6800 series coach), but the upper deck is about the most spacious rail vehicle I've ever travelled in (I didn't sample the lower deck). No squashed knees in these!

 

[HSTEd]

I'd say very generous ....

Admittedly this is business class (6800 series coach), but the upper deck is about the most spacious rail vehicle I've ever travelled in (I didn't sample the lower deck). No squashed knees in these!

View attachment 179002 View attachment 179003

As far as I can tell the business class cars are primarily a booking thing more than an actual change in comfort.

Downstairs the seats are apparently 2+1 to make more room for the gangway.

Just goes to show that number of seats is not the only parameter. With a denser seating layout they would be able to fit enormous numbers of people.

 

[Trainbike46]

Theoretically, having double-decker trains would mean more seats, which therefore would mean fewer people standing. And if a person is seated, then height wouldn't matter quite so much. But boarding and alighting would still be less than ideal. Big hombre me already has to deal with shorter ceilings on double-decker buses, although I don't really think about it once I've sat down. But people aren't supposed to stand upstairs on buses; I don't think that kind of restriction would apply to trains, but standees would be less than happy!

Does anyone stand upstairs on European double deckers anyway? I can't remember whether I needed to stoop slightly to walk through the train or not on my last experience (the photo is from upstairs on a Belgian double decker) but I can't imagine anyone standing there instead of the open area by the doors.

View attachment 178976

You're both forgetting that people have to get to the seats - so standing height is very relevant.

In the Netherlands standing on both decks of double-decker units is pretty common during busy times, on both VIRM and DDZ stock.

Double decker buses have 30cm more height available than fits in the UK railway loading gauge, and still tall people often can't stand upright on the upstairs deck. In addition to the calculations I did upthread, that makes clear that a double decker that is both usable and fits in the UK loading gauge simply isn't feasible.

(relevant posts from me and others quoted below)

To give an idea of just how cramped this would be, an Alexander Dennis Enviro400 double decker bus is 4.2 to 4.3m high depending on the height specified. And upstairs is pretty cramped on those already without having to lose an additional 30cm or so between the two decks.

It's just not feasible.

The minimum acceptable ceiling height would be somewhere between 2sigma and 3sigma above the average men's height. If using 2sigma, about 2.5% of men wouldn't be able to stand upright. If using 3sigma this decreases to 0.15%*.

For the UK this means, with a mean of 175.9 cm in 2021, and an estimated standard deviation of 6-8 cm (which I'm taking as 7 cm), that gives a 2sigma level of 189.9 cm and a 3sigma level of 196.9 cm. You then need to add the allowances for the dynamic envelope of walking on top of that.

If you want to even slightly futureproof your new trains (and you should, as they'll last ~40 years), you use the average height of 16-24yo men instead, which is 178.8, which gives 192.8 cm for 2sigma, and 199.8 cm for 3sigma, and once again the allowances for the dynamic envelope of walking should be added on top of that.

While the final numbers chosen will depend on what the acceptable number of people hitting their head is, it seems unlike anything less than 2m would be a terrible idea. However, even using the 2sigma numbers, no future proofing, and no allowance for the dynamic envelope of walking the minimum comes to 190cm, and even that only gives you a total of 16.5 cm for everything between the railhead and the top of the loading gauge that isn't passenger space. It simply cannot be made to fit. Of course, back in the real world, where the minimum height for passenger space really should be at least 2m (and ideally more), it most certainly can't fit.

*assuming height within a gender approximately follows a normal distribution, according to the 3sigma rule. This is half the values lying more than 2/3sigma from the mean, as the other half of those values would be expected to be at the low end. Using men's height as women are, in the UK, on average shorter.

 

[Mikey C]

You're both forgetting that people have to get to the seats - so standing height is very relevant.

In the Netherlands standing on both decks of double-decker units is pretty common during busy times, on both VIRM and DDZ stock.

Double decker buses have 30cm more height available than fits in the UK railway loading gauge, and still tall people often can't stand upright on the upstairs deck. In addition to the calculations I did upthread, that makes clear that a double decker that is both usable and fits in the UK loading gauge simply isn't feasible.

There is a difference though between slightly stooping to get to your seat, and having to stoop for a significant period of time because there are no seats. On the upper deck of buses standing isn't allowed, so you just need enough headroom to "comfortably" be able to walk down the bus, even if you are tall.

It's not ideal, but an upper deck with no standing passengers could be created.

 

[Trainbike46]

There is a difference though between slightly stooping to get to your seat, and having to stoop for a significant period of time because there are no seats. On the upper deck of buses standing isn't allowed, so you just need enough headroom to "comfortably" be able to walk down the bus, even if you are tall.

It's not ideal, but an upper deck with no standing passengers could be created.

Not with 30 cm less height available than a double-decker bus, which is already pushing the limits of what is possible/acceptable by requiring stooping. Where is that 30cm of height coming from?

 

[Zomboid]

Bus bodywork is pretty thin too, I'd be amazed if it met current rail crashworthiness standards without increasing in bulk, so even less space in the passenger saloons.

 

[HSTEd]

It seems unlikely that an attractive double decker train can be fitted into the UK loading gauge without major structural work.

If you are going to have to rebuild most bridges to get enough clearance for a minimum height double decker train, whats the cost increment of rebuilding to a higher clearance and getting roomier and likely more practical double decker trains?

If we accept that (almost) all bridges over the railway will need rebuilding anyway, we can avoid rebuild of platforms and such by moving the lower deck floor height to 1000mm or so.
Indeed, once you do that, it may even be possible to provide continuous passages on both decks, which would make a double decker more operationally attractive.;

Once you commit to work for double decks, you might as well commit to work for double decks.

 

[MotCO]

The Telegraph is reporting that Eurostar and Virgin are thinking about placing an order for double deck trains on the cross-channel routes.

Double-decker trains could soon run from London to Paris

Plans by Virgin and Eurostar would significantly increase capacity on busy Channel Tunnel route

www.telegraph.co.uk

Double-decker trains could soon run from London to Paris​

Plans by Virgin and Eurostar would significantly increase capacity on busy Channel Tunnel route


14 May 2025 1:46pm BST


Double-decker trains could run through the Channel Tunnel by the end of the decade under plans being drawn up by Eurostar and Sir Richard Branson’s Virgin Group.
The rival rail operators are contemplating orders of a two-tier version of the French TGV train, in a move that would significantly increase capacity on the busy London-Paris route.
It would also give Britons a taste of the double-decker train travel that has been commonplace in continental Europe for decades.
Eurostar said that opting for a double-decker design is “a possibility” as it moves towards placing an order for up to 50 new trains by the end of this year.
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Talks are under way with multiple manufacturers for the order, a spokesman said. Those include Alstom, the manufacturer of the original fleet of TGV-based Eurostar trains that are capable of speeds of 350 km/h (217 mph).
Eurostar’s majority owner, French state railway SNCF, has operated twin-deck TGVs since 1996.

Sir Richard’s Virgin Group also said it would consider double-deckers as it bids to operate trains through the Channel Tunnel in competition with Eurostar.
A spokesman said potential suppliers included Alstom as it seeks “the best trains to meet our cross-Channel rail ambitions”.
Opting for a high-capacity model might enhance Virgin’s credentials amid efforts to win approval for the move from UK regulators.
Gemini Trains, led by rail industry expert Lord Tony Berkeley, and Evolyn of Spain, which is working with Italy’s state rail operator, are also in the running to end Eurostar’s 30-year monopoly on cross-Channel services
Henri Poupart-Lafarge, Alstom’s boss, said it was in talks to run double-decker trains through the Channel Tunnel, where he said they could both increase capacity and bring down fares.

He told the Financial Times: “The double-decker train has a lot of advantages. It’s a very high-speed train with the lowest cost per seat and the highest capacity.”

The High Speed 1 line from Folkestone to St Pancras station was built to European standards, meaning there should be no issue in accommodating the increased height of the trains, an Alstom spokesman said.


While gaining approval for double-deckers to run through the tunnel would take some years, they should be available within the timescales being explored by Eurostar and Virgin.
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However, Alstom has limited production capacity and outstanding orders for the two-tier TGV, so it may be a case of “first come, first served” in bringing the trains to the Tunnel, he said.
The firm’s newest twin-deck model, the Avelia Horizon, which has more than 100 orders, is set for its first delivery next year.
While the top level of a double-decker offers a better view for passengers, the trains have a mixed reputation in Europe.
Stairs to the top level can be hard to negotiate for some passengers and boarding times are inevitably longer. A seat on the bottom deck also tends to be lower and can require steps down.
Britain’s only foray into double-decker trains came after Second World War, when two experimental commuter models served London Charing Cross.

 

[duffield]

The Telegraph is reporting that Eurostar and Virgin are thinking about placing an order for double deck trains on the cross-channel routes.

Double-decker trains could soon run from London to Paris

Plans by Virgin and Eurostar would significantly increase capacity on busy Channel Tunnel route

www.telegraph.co.uk

The first thing that occurred to me was whether they could evacuate such trains in an acceptable amount of time in the event of a fire while in the tunnel. I think it has special evacuation requirements, and potentially that might make this a non-starter. But I'm a bit vague on this, I hope someone with more knowledge on the subject can provide some more detail. Maybe such trains already run through similar long tunnels like the Gothard base tunnel, so maybe it's not an issue?

 

[joieman]

The first thing that occurred to me was whether they could evacuate such trains in an acceptable amount of time in the event of a fire while in the tunnel. I think it has special evacuation requirements, and potentially that might make this a non-starter. But I'm a bit vague on this, I hope someone with more knowledge on the subject can provide some more detail. Maybe such trains already run through similar long tunnels like the Gothard base tunnel, so maybe it's not an issue?

If they're considering it at this stage then I reckon it's reasonably feasible.

 

[ShadowKnight]

Also there are already double deck car shuttle trains through the channel tunnel so it won't be a complete unknown

 

[zwk500]

The first thing that occurred to me was whether they could evacuate such trains in an acceptable amount of time in the event of a fire while in the tunnel. I think it has special evacuation requirements, and potentially that might make this a non-starter. But I'm a bit vague on this, I hope someone with more knowledge on the subject can provide some more detail. Maybe such trains already run through similar long tunnels like the Gothard base tunnel, so maybe it's not an issue?

An important difference between the Alpine tunnels and the Channel Tunnel is the lack of ability to perform a mid-point evacuation, for obvious reasons. The Channel Tunnel has a service tunnel and a lot of ventilation engineering connecting all 3 tubes to allow the service tunnel to function as a refuge, but it still then means a potentially 25km evacuation back to the nearest portal. If you're really unlucky it could mean a potential 50km to the further portal. Therefore the normal TSI standards are amended slightly for the Channel Tunnel stock acceptance.

Essentially, the primary fire evacuation strategy is that a train drive out of the tunnel and then perform a normal evacuation on the surface. This requires that it meets all the fire protection standards for a minimum of 30 minutes, the normal transit time for the tunnel. This is longer than the usual requirement of 15 minutes (intended to provide safe time for an immediate evacuation). However trains that only meet the 15 minutes requirement and not the 30 minutes requirement are able to be cleared for the tunnel if they can demonstrate in an additional safety analysis that they do not negatively impact the safety of the channel tunnel, which includes being able to safely evacuate to the service tunnel.

The latest documents available from the Intergovernmental commission (IGC) https://www.channeltunneligc.co.uk/-Regulations-and-guidance-.html?lang=en

Double decker passenger trains will not of themselves be a show-stopper, but if the TGV-M can't meet (or be adapted to meet) the 30-minutes fire protection requirements then they will need to demonstrate a full passenger load could be safely evacuated to the service tunnel, and then safely evacuated from the service tunnel, without compromising the existing safety standards.

 

[duffield]

An important difference between the Alpine tunnels and the Channel Tunnel is the lack of ability to perform a mid-point evacuation, for obvious reasons. The Channel Tunnel has a service tunnel and a lot of ventilation engineering connecting all 3 tubes to allow the service tunnel to function as a refuge, but it still then means a potentially 25km evacuation back to the nearest portal. If you're really unlucky it could mean a potential 50km to the further portal. Therefore the normal TSI standards are amended slightly for the Channel Tunnel stock acceptance.

Essentially, the primary fire evacuation strategy is that a train drive out of the tunnel and then perform a normal evacuation on the surface. This requires that it meets all the fire protection standards for a minimum of 30 minutes, the normal transit time for the tunnel. This is longer than the usual requirement of 15 minutes (intended to provide safe time for an immediate evacuation). However trains that only meet the 15 minutes requirement and not the 30 minutes requirement are able to be cleared for the tunnel if they can demonstrate in an additional safety analysis that they do not negatively impact the safety of the channel tunnel, which includes being able to safely evacuate to the service tunnel.

The latest documents available from the Intergovernmental commission (IGC) https://www.channeltunneligc.co.uk/-Regulations-and-guidance-.html?lang=en

Double decker passenger trains will not of themselves be a show-stopper, but if the TGV-M can't meet (or be adapted to meet) the 30-minutes fire protection requirements then they will need to demonstrate a full passenger load could be safely evacuated to the service tunnel, and then safely evacuated from the service tunnel, without compromising the existing safety standards.

Thanks for the comprehensive reply.

 

[MotCO]

The first thing that occurred to me was whether they could evacuate such trains in an acceptable amount of time in the event of a fire while in the tunnel. I think it has special evacuation requirements, and potentially that might make this a non-starter. But I'm a bit vague on this, I hope someone with more knowledge on the subject can provide some more detail. Maybe such trains already run through similar long tunnels like the Gothard base tunnel, so maybe it's not an issue?

The tunnel has emergency exits every 375m, so trains have to have doors this far apart. Also, in the event of a fire, there are a number of 'water curtains' to dowse the flames, so the trains must be able to pass through these.

 

[quantinghome]

Double deck trains on cross-channel services would also need a substantial increase in security and border control capacity at the stations, particularly if low-cost operators give it a go (it sounds like a doubled-up TGV-M in a lost cost configuration would have about 1500 seats - great if it can be made to work).

Would the TGV-M be able to operate in pairs through the tunnel or would it need to be a single 400m train? If the latter, how would that work with the power cars?

 

[43096]

The tunnel has emergency exits every 375m, so trains have to have doors this far apart.

This “fact” keeps cropping up, but doesn’t stand up to scrutiny. A full length 373 set is around 343m for the passenger vehicles (excluding power cars) and a NoL set is around 275m for the passenger vehicles. Both have been used through the tunnel in passenger service.

 

[RT4038]

Double deck trains on cross-channel services would also need a substantial increase in security and border control capacity at the stations, particularly if low-cost operators give it a go (it sounds like a doubled-up TGV-M in a lost cost configuration would have about 1500 seats - great if it can be made to work).

In these cramped double deckers, where is all the luggage going to go, bearing in mind that virtually everyone on these services travels with at least some item of luggage, and many people carrying plenty?

 

[Bletchleyite]

In these cramped double deckers, where is all the luggage going to go, bearing in mind that virtually everyone on these services travels with at least some item of luggage, and many people carrying plenty?

Lumo have proven that low cost operations can still sell tickets with very stringent luggage restrictions, so the answer to that might be "not at all". And because of the security checks it would be feasible to actually enforce it, unlike domestic trains.

 

[MotCO]

This “fact” keeps cropping up, but doesn’t stand up to scrutiny. A full length 373 set is around 343m for the passenger vehicles (excluding power cars) and a NoL set is around 275m for the passenger vehicles. Both have been used through the tunnel in passenger service.

All I can say is that this was told to me by a guide who was taking me through the service tunnel on a visit for emergency response training.

 

[zwk500]

The tunnel has emergency exits every 375m, so trains have to have doors this far apart.

I've looked through the IGC documentation quite closely, and cannot see this requirement in current documents. Happy to be corrected!

 

[martin2345uk]

Would the TGV-M be able to operate in pairs through the tunnel or would it need to be a single 400m train? If the latter, how would that work with the power cars?

Eurostar are considering this as an option so must be reasonably confident it can work in practice.