The Avelia Horizon trains Eurostar has ordered from Alstom are not compliant with Channel Tunnel evacuation rules – what can be done about it?

*** This post is an adapted version of one part of my #CrossChannelRail Project Final Report ***

The two existing train types that operate long distance high speed services through the Channel Tunnel (TMST and Siemens Velaro 16 carriage version) are both single units, each train type just under 400m in length. Yet none of the trains that Eurostar or any of its rivals are considering purchasing have this format. Instead trains around 200m length would be purchased, with the opportunity to couple two of them together to make a 400m long formation.

The notion has long persisted that trains must be long single units as cross passages to the service tunnel in the Channel Tunnel are 375m apart, but this is not the case – a 2x 200m formation is permitted in principle. This was the system Deutsche Bahn wanted to use for its planned London trains in the early 2010s, before aborting the plans.

Ordering 200m trains brings numerous advantages. First, all the main manufacturers are offering their high speed trains as 200m units as this fits with operational models on high speed networks elsewhere in Europe. Second, in the specific case of the Channel Tunnel operations, it allows some stations to be served that could not accommodate a 400m train (my #CrossChannelRail report explores these options in different stations). And third, it allows a train to be split somewhere en route, to allow one train departing from London to serve multiple destinations.

However the 2x 200m format can pose some practical problems with regard to evacuation rules in the Channel Tunnel. Rules for this make a distinction between a controlled and an uncontrolled stop of a train in an emergency situation.

An uncontrolled stop happens in the case of an immediate danger – the train that passengers are on is on fire for example. Priority here is to get everyone out as fast as possible. However how these situations are handled has been beset with confusion in the public debate for years. The idea has erroneously persisted that a minimum train length of 375m is required for trains to be allowed to operate, so as to ensure there would always be at least one passenger door close to a cross passage to the service tunnel. But LeShuttle truck shuttles (where drivers are sat in a single carriage), and proposed North of London TMST trains and Nightstar night trains have never had 375m length of the passenger compartment, nor a way for passengers to get through the train in the case of a truck shuttle. In these cases the walkway along the side of the running tunnel would have to be used for evacuation in the case of an uncontrolled stop, and so would be the case for a high speed passenger train.

But train door placement does matter in the case of an evacuation with a controlled stop, albeit in a slightly different way. And that is what is a concern here.

A controlled stop is where the train with the passengers on board is not in an immediately critical situation, and the driver can bring the train to a standstill at a designated place in the tunnel as required. However this includes the case of a power cut, or smoke ingress in the running tunnel from a fire on board another train.

With current rolling stock used through the Channel Tunnel the procedure in the case of a controlled stop means aligning the front passenger door with a cross-passage between the running tunnel and the service tunnel, to allow evacuation through that door. Evacuation can be through another door or doors onto the walkway in the running tunnel as well if the safety situation allows, even if those doors are not near a cross passage, but the principle is clear: a one door evacuation is permissible and in some cases necessary or desirable.

Once the driver has stopped the train aligned with the cross-passage (there are markers in the running tunnel for this purpose), all passengers can be evacuated there. Persons with reduced mobility and wheelchair users can also be evacuated through this one door, and special narrow evacuation wheelchairs are carried on board and can be pushed along the aisle by on-board staff (train managers or catering staff). Wheelchair users’ own wheelchairs are likely too wide to pass along the middle aisle of the train, so are left behind.

Existing TMST and 16 carriage Velaro trains have two important common features in this regard: they are single deck trains, with both a level floor inside and continuous aisle throughout the train, allowing passengers and the evacuation wheelchairs to pass along the entire train without restriction.

It is obvious that operating a single 200m unit would comply with these rules (and for any of the 200m train types), as evacuation could be through just one door in these cases. For the Avelia Horizon, without a continuous corridor at the lower level, the evacuation door would have to be the door where wheelchair users are located.

However coupling 2x 200m units together calls this system into question.

In the case of a two unit train formation – were a controlled stop leading to an evacuation is needed in the tunnel – passengers will have to be evacuated from front and back units separately, as there is no through passage between the two units. Evacuation from one door only is impossible.

Evacuation cross-passages in the Channel Tunnel are on average at 375m intervals. The most obvious solution would be to align a door of the front unit with one cross-passage (+/- 5m) and align a door of the rear unit with the following cross-passage (+/- 5m). This is all explained in “Technical Investigation Report concerning the Fire on Eurotunnel Freight Shuttle 7412 on 11 September 2008” and it de facto would mean 365m to 385m between train doors is necessary (likely the front door of the front unit and the back door of the back unit).

Train types with distributed traction – Siemens Velaro 8 carriage or Velaro Novo 7 carriage, Alstom Avelia Stream, and Hitachi ETR1000 – have passenger cabins and doors throughout almost the whole length of the unit, including just behind the driver’s cab, although in the Hitachi case it is only a service door, like this:

For example in the case of the 8 carriage Velaro in service for Deutsche Bahn as ICE3neo, the distance from the front of the nose to the middle of the first passenger door is 8.4m, meaning the distance between the front door of the front unit to the back door of the back unit is 384.6m – just within the safe limit.

However the Alstom Avelia Horizon and Talgo Avril have power cars at the front and rear of each 200m unit, and in the case of Avelia Horizon the passenger door is at the rear of the first carriage. I focus here on the Avelia Horizon as that has been ordered by Eurostar, while operations of the Talgo Avril are only a theoretical possibility for now.

The distance from the front of the nose of an Avelia Horizon to the middle of the first door a passenger could access is more than 34m. That means the distance from the first passenger door on the front unit to the back passenger back door on the back unit is just 333m, more than 30m short of the 365m that would be required.

Even if the format of the first carriage could be reversed to put the door at the front of the carriage, the distance from nose to middle of the door would still be 24m, so front door of front unit to back door of back unit would still be only 353m, still missing by 12m. Scale diagrams of both of these cases are in this PDF.

While the front unit could be evacuated directly into a cross passage, the back unit could not. Passengers (including wheelchair users) would need to use the walkway along the running tunnel that currently can be avoided in controlled stop situations. Were the running tunnel filled with smoke – as was the case in the 2008 fire – this situation is not ideal.

Theoretically there would be other ways to solve this problem, but they each have their own downsides.

Running only a single 200m Avelia Horizon train, rather than 2 coupled together, would of course be permissible. But as each 200m unit is to have 540 seats, versus 758 in a TMST and 902 in a 16 carriage Velaro, that might be OK for off peak services but it is no good for peak hours services, not least as the 8 remaining TMST trains are end of life and need to be replaced.

Lengthening each unit from 200m to c. 218m – making a Avelia Horizon 10 rather than 9 carriages for example – would solve the door placement problem, but would mean two trains coupled would exceed 400m and hence would not fit the platforms in Paris Gare du Nord, where platforms are only just over 400m total length and hard to extend. So this can be ruled out.

Splitting the train in two in the case of a controlled stop could be a solution. The train would be stopped, split, and one half would be moved after the stop. However this would have to function even in the case of a power cut, so would need on board battery packs. But batteries present their own fire risk, and batteries had to be specially designed for existing Channel Tunnel trains even for matters as mundane and low power as emergency lighting. It is unknown if the Avelia Horizon backup battery to move the train would be permitted in the Channel Tunnel – more about that system here.

Alternatively the Channel Tunnel Safety Authority could decide to amend the procedures to suit new train types. Or the manufacturer or operator of a train compliant with the EU Technical Standards of Interoperability could argue that EU law is supreme over national law, and hence the train must be approved. But that would take years to prove, whatever the outcome, and would present the risk of delays approving the train. That would put the 2031 entry into service of these Avelia Horizon trains in some question.

Given the very real experience of fires in the Channel Tunnel, especially the 2008 case that resulted in the formulation of the evacuation rules as they are currently, there is a genuine issue here that must be adequately addressed before 2 coupled Avelia Horizon 200m trains can run safely.

And all of this could perhaps explain why Eurostar has ordered only 30 and not 50 Avelia Horizon trains. The company could use the Avelia Horizon units to replace its PBA and PBKA fleet on ex-Thalys routes, and eventually order something else for the Channel Tunnel.

Images used in this post

Velaro Novo high-speed train. Source: © Siemens AG, press image. ID: f5cc3704-b5ff-439b-a9a1-630c85f9944f

Computer rendering of Virgin Trains’ future Avelia Stream. © VTE HOLDINGS.

Eurotunnel schema (empty service)
Original by Arz, tiny modification by Commander Keane
February 19, 2018
Public domain

DSC_0802
Cheng-en Cheng
September 26, 2019
CC BY-SA 2.0

Le TGV M à la gare de Lyon lors de sa présentation le 31 juillet 2023.
Rémi Simonnin
July 31, 2023
CC BY-SA 4.0

Other photos and diagrams are mine.

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