The new Alstom built SNCF TGV flagship train – the TGV-M – was presented in Paris today. The launch offered the first look at the interior of the train that ought to be running on tracks in France sometime in 2026, all being well. If that aspect interests you, see this Le Figaro story.

My preoccupation just now is a different one – future services through the Channel Tunnel. And it has been heavily rumoured that Eurostar is likely to place an order for this type of train, although so far no contract has been signed, as confirmed in this interview with Eurostar CEO Cazenave last month. Private firm Evolyn has also been exploring buying trains of this type. However seeing pictures from the launch made me start to wonder whether we have missed a reason for the delay getting these deals done.

While I am often asked the question whether double decker trains can reach St Pancras on HS1 – the answer is obviously yes as the loading gauge permits it. The problems, it turns out, are at the bottom of these trains, not the top.

It is all about doors, platforms, and boarding the train.

This is quite technical, but bear with me, and I will do my best to explain it all.

The first thing to consider is platform height. Platforms at railway stations in Europe are generally built to one of two standards – 550mm above the height of the rail, or 760mm above height of rail. All platforms for high speed trains in France are 550mm, but along HS1 in UK, and in Belgium, Netherlands, and western Germany the platform height is 760mm. That means a train running Paris to London, or indeed Paris – Bruxelles, needs to cope with both heights.

TGV-M, like the predecessor TGV Duplex, is designed for 550mm platforms, and allows step free access into the train at that height – as this picture from today’s launch shows:

The common issue in the past was that the floor of a train was higher than the platform – and this then meant stairs inside the train up to floor level – you can see this here on the Bruxelles-Paris OUIGO service:

And getting into such a train with a wheelchair needs a lift or ramp on the platform – this is how it is done in Germany:

However the TGV-M poses the opposite problem – from a 760mm platform you have to step down, or get a wheelchair down into the train. And as if that were not enough, even though the bottom of the door of a TGV is at 550mm, the floor is lower still, at about 300mm above the rail, so you need to go down further once you are inside.

And that poses numerous problems.

Let us first look at what the law says.

Commission Regulation (EU) 1300/2014 on the technical specifications for interoperability relating to accessibility of the Union’s rail system* for persons with disabilities and persons with reduced mobility is what we need to look at (all languages, and PDF and HTML versions of it here).

Access using steps is covered in 4.2.2.11.1., with tables for 550mm and 760mm platforms. And δν– mm – the distance a passenger can safely be expected to step down into a train from a 760mm platform is just 160mm. But the difference between 550mm and 760mm is 210mm!

So that means the TGV-M as designed for SNCF and previewed today can only legally be used at stations with 550mm platforms**. It cannot be used at 760mm platforms.

To overcome this some additional solution would have to be engineered here – an additional step that pops upwards, built in at every door.

The situation for wheelchair users at 760mm platforms also looks tricky.

SNCF lauded the new interior lift for wheelchair users in the TGV-M at the launch today – this is what it looks like:

A wheelchair enters from the 550mm platform, and is then turned 90 degrees to the right and lowered to the 300mm floor height.

But again, what about 760mm platforms?

Here you need to put some sort of ramp inside the train – something like this:

You could see, just about, how this could work in the TGV-M – with the extra ramp shown in red laid into the lift, after the lift had been turned to face the door. But you would need a railway employee present to make this work.

The Regulation 1300/2014 is a little contradictory on ramp gradients – these are stipulated in 4.2.2.8. in general, while 5.3.2.9. on boarding ramps states a slope of 18% is permissible for entry-exit. If we take the latter more generous figure that means a ramp approximately 1.2m in length (that a train manager could lay down) would cover the 210mm height difference. Not a swift or elegant solution, but at least technically compliant with 1300/2014, and similar to the system used in older TGV Duplex trains at German 760mm platforms (pictures of this system here).

A more elegant solution would be to engineer the wheelchair lift to rise all the way up to a height of 760mm, meaning only a flat bridge would be needed to cross the gap to the platform. But this is not built into the TGV-M for SNCF showcased today.

But thinking more fundamentally, is there any other solution here?

Maybe the solution is indeed to look up.

The lower floor of the double deck carriages of Siemens Desiro HC EMUs for services around Berlin have step free doors into the bottom floor of double deck carriages for both 550mm and 760mm platform heights (see Page 7 of the Siemens publicity PDF for how it’s done) but doing this in a TGV would bring you another problem – very limited headroom on the lower floor.

However the loading gauge in Germany – G2 as standard, GC for new builds – allows a total vehicle height of around 4650mm. This is about 300mm higher than the 4320mm total height of a TGV-M which – like the 550mm platform height – is the standard for France. Add an extra 320mm to the height of your carriage and you have extra room for steps and/or lifts or even fixed sloping floors inside the lower floor of your train.

French high speed lines – built since the 1980s – have been built to the UIC GC standard, so 4650mm would work there, including from the Channel Tunnel all the way to the edge of Paris. It is on French older lines – including on the 16km approach to Paris Gare du Nord – that some loading gauge works would be required. But you could envisage a higher 4650mm TGV-M version for Channel Tunnel services, and for France-Belgium-Netherlands services too, and the current 4320mm version for services within France, and to Italy and Switzerland – all places with 550mm platforms. The cost and complexity of doing this is likely to be considerable!

But overall the conclusion here is clear: TGV-M, as currently engineered for SNCF, cannot legally be used with 760mm platforms. And that means not to London, not to Bruxelles, not to Amsterdam, and not to much of Germany. And that might just be the reason Eurostar (and Evolyn) have not concluded contracts to buy these trains yet.

Credits

Loads of people have helped me understand this topic – on both Mastodon (Edmund Lauterbach, Jos Dingjan, wibble, Sarah Wilson, Tursiae, Tenkoman) and Bluesky (Arian, tristramg, Frankyman, Max Wyss, Torsten, ‪Fahrradfreundlicher Arbeitgeber‬, Lennart Fahnenmüller). Particular credit to Sam Jennings on Bluesky who gave me the kick I needed to look into all of this! However any errors that appear in this text are mine, and mine alone. If any of the text here proves to be incorrect, I will correct the text and make it clear what changes were made.

Notes

* – even though the UK is outside the EU, any train transiting the Channel Tunnel has to enter EU territory, so these rules still apply. The UK has also implemented these rules nationally – thanks Will Deakin.
** – the older TGV Duplex design pre-dates regulation 1300/2014, so will have grandfathering rights, and hence could be used in these cases. In addition this means TGV-M, in this form, also cannot run to Spain – as 760mm is the platform height there too, while TGV Duplex is running there.

Images used in this post

Pictures of the TGV-M have been sent to me by a friend, and are used with permission – but cannot be re-used. The OUIGO train with steps picture, and the wheelchair ramp sketch are mine, and can be re-used. Other photos are CC licensed, as follows:

Arne List
Klappe hoch
October 16, 2009
CC BY-SA 2.0