Channel Tunnel 2

[mike57]

From a purely economic point of view a second tunnel is not going to happen, not parallel, not somewhere else. The investors in the current tunnel lost loads of money, they are not going to invest in a second financial black hole.

The current tunnel is not at capacity, and even when (if?) it is there are other things that could be done to squeeze more out of what we have without embarking on a second tunnel

A road bridge is feasible but no one will pay for it. Given the state of both the British and French economies government money from either side is unlikely to be forthcoming in the foreseeable future.

 

[TheWierdOne]

One factor against the current tunnel being a road was exhaust fumes- something that will no longer be a problem if the switch to EVs progresses the way people hope it will.
The main problem then becomes where do you have the changeover point from driving on the left to driving on the right... At least until all vehicles are autonomous, at which point tunnel effect and light hallucination cease to be a problem too.

You do of course swap the emissions problems for the scenario of a battery fire inside the tunnel. I’m not sure I fancy war-gaming a lithium fire in a confined space with 40 metres of water overhead.

 

[Ploughman]

simple, one of top of the other

Corkscrew.

 

[TheGrew]

You do of course swap the emissions problems for the scenario of a battery fire inside the tunnel. I’m not sure I fancy war-gaming a lithium fire in a confined space with 40 metres of water overhead.

Quite, and I drive an EV! I wonder if you could create a system with individual-powered sleds that cars are attached to and then shuttled across. I appreciate that this is pretty similar to a train, but I am thinking something more akin to a scaled-up personal rapid transit system like the Heathrow Pods or the Morgantown PRT. You could have a much more turn-up-and-go service with automatic operation.

 

[Mgameing123]

One factor against the current tunnel being a road was exhaust fumes- something that will no longer be a problem if the switch to EVs progresses the way people hope it will.
The main problem then becomes where do you have the changeover point from driving on the left to driving on the right... At least until all vehicles are autonomous, at which point tunnel effect and light hallucination cease to be a problem too.

The changeover point shouldn’t be in the tunnel. It would be better to do it either on the UK or French side.

 

[FGWHST43009]

Quite, and I drive an EV! I wonder if you could create a system with individual-powered sleds that cars are attached to and then shuttled across. I appreciate that this is pretty similar to a train, but I am thinking something more akin to a scaled-up personal rapid transit system like the Heathrow Pods or the Morgantown PRT. You could have a much more turn-up-and-go service with automatic operation.

Real-life size Scalextric? That would be rather cool! Wasn't that the original Loop plan from Elon Musk?

On the wider subject of cross-channel connectivity, I think through HS2 services are probably more likely to happen than a second Channel Tunnel. Unless there's a surge in rail traffic, it's unlikely to happen. Although through HS2 services would mean the existing tunnel gets more use. It would be interesting if the number of passenger trains increases to the point where a real hard think is needed about the timetable and the mixing with the Shuttles. If HS2 was built in full with a connection to CTRL, then I think the higher speeds available on HS2 would make through services to Europe more attractive.

 

[61653 HTAFC]

Quite, and I drive an EV! I wonder if you could create a system with individual-powered sleds that cars are attached to and then shuttled across. I appreciate that this is pretty similar to a train, but I am thinking something more akin to a scaled-up personal rapid transit system like the Heathrow Pods or the Morgantown PRT. You could have a much more turn-up-and-go service with automatic operation.

Careful now... You'll have the EVangelists from the Electric Vehicles thread insisting that battery fires aren't a big deal!

The changeover point shouldn’t be in the tunnel. It would be better to do it either on the UK or French side.

I didn't say it would be, that would just make the digging of the tunnels needlessly complicated (as even with 100% autonomous vehicles you'd want two separate tunnels for each direction). Just that once all vehicles are autonomous, it wouldn't matter which side of the channel you put the changeover point on, and that the negative effects on human drivers of driving through a long tunnel wouldn't be relevant.
Though it's all academic anyway as I don't believe autonomous vehicles will ever become a universal thing, certainly not within the lifetime of any member of this website.

 

[Transilien]

i would actually suggest a mid-life Upgrade to the existing Tunnel with more cross passages to allow 2x200m unit easier, to allow it to reach 200km/h, ETCS etc
alongside new Le Train rolling stock to allow higher speeds there and up capacity in general

Mid-life? Does that mean that the channel tunnel will have to be replaced eventually? The Severn tunnel is still operating well today despite being from the 19th century and having a Victorian design.

 

[TheWierdOne]

Mid-life? Does that mean that the channel tunnel will have to be replaced eventually? The Severn tunnel is still operating well today despite being from the 19th century and having a Victorian design.

I think "operating well" is a generous term given the restrictions on train movements (related to dangerous freight) and very heavy water ingress. It does certainly operate, but the Victorian design is certainly a problem.

== Doublepost prevention - post automatically merged: 13 Nov 2025 ==

Quite, and I drive an EV! I wonder if you could create a system with individual-powered sleds that cars are attached to and then shuttled across. I appreciate that this is pretty similar to a train, but I am thinking something more akin to a scaled-up personal rapid transit system like the Heathrow Pods or the Morgantown PRT. You could have a much more turn-up-and-go service with automatic operation.

To make it more efficient you could run sleds in groups leaving at fixed but frequent intervals, you could even mount the sleds on some sort of guideway, rails if you will, to reduce the energy consumption. You'd want a constant power supply of course to avoid the risk of battery fires, and ideally it would use parts common to transport systems in one or both of France or the UK. Does anyone know of a transport method we could adapt potentially?

 

[Mgameing123]

Mid-life? Does that mean that the channel tunnel will have to be replaced eventually? The Severn tunnel is still operating well today despite being from the 19th century and having a Victorian design.

The Severn Tunnel is not really doing well when you need a powerful pump to keep it from not flooding.

 

[zwk500]

I didn't say it would be, that would just make the digging of the tunnels needlessly complicated (as even with 100% autonomous vehicles you'd want two separate tunnels for each direction). Just that once all vehicles are autonomous, it wouldn't matter which side of the channel you put the changeover point on, and that the negative effects on human drivers of driving through a long tunnel wouldn't be relevant.
Though it's all academic anyway as I don't believe autonomous vehicles will ever become a universal thing, certainly not within the lifetime of any member of this website.

Tbf it wouldn't be that difficult, you'd just swerve one bore down and across while the other goes up and around. The service tunnel already does this. It'd probably be slightly easier to have the exchange on land for operational purposes but with 1 carriageway in each direction swapping from left to right hand isn't especially difficult.

To be pedantic, the current Channel Tunnel is already the second one. The remnants of the first one from the 1880s can still be accessed from a brick structure at the base of Shakespeare Cliff and the current tunnel actually intersects with part of the Victorian era one.

To be really pedantic, it's actually the 3rd, 4th and 5th tunnels if you only count ones work was started on. 1882, 1974 and then the 3 bores for the current fixed link.

Hello everyone. I was wondering about the future of cross-channel services. The channel tunnel isn't at capacity yet but when it is, where would a new one be?

Maybe perhaps between Cherbourg and Bournemouth or the Isle of Wight.
A new pair of tunnels right next to the existing ones?

Make you suggestions!

The most profitable market is London-Paris. The most direct line between those cities would therefore be the optimum place to build another Channel Tunnel, so Sussex-Normandy. Combine it with LGV Normandie and you could have London-Gatwick-Brighton-Rouen-Paris.
However I agree with previous posters that for pragmatic reasons any expansion of the Channel Tunnel will almost certainly be alongside the existing fixed link.

I also agree that it's nowhere near full capacity or needing an upgrade yet and there are other projects higher up the list. A 2nd fixed link to the continent is probably at a similar level of priority as a fixed link across the Irish Sea..

 

[HSTEd]

A drive through crossing would likely be a viaduct/bridge rather than a tunnel, which avoids all the associated problems with ventilation and fires.

Of course, with improvements in immersed tube technology, a tunnel may not even be bored.
The Fehmarn Belt fixed link is an ~18km immersed tube, although the seabed is only 35m down there. I believe the Channel is significantly deeper.

 

[61653 HTAFC]

A drive through crossing would likely be a viaduct/bridge rather than a tunnel, which avoids all the associated problems with ventilation and fires.

Of course, with improvements in immersed tube technology, a tunnel may not even be bored.
The Fehmarn Belt fixed link is an ~18km immersed tube, although the seabed is only 35m down there. I believe the Channel is significantly deeper.

Sea depth is as much (arguably more) of a hindrance to a bridge. Especially considering that the Channel is one of the busiest shipping areas in the world. Your bridge deck would need to be high enough to accommodate the largest container ships (and with some room to spare allowing for bigger ships in the future) or have a lifting section which somewhat defeats the object.

 

[Transilien]

The Severn Tunnel is not really doing well when you need a powerful pump to keep it from not flooding.

Will the channel tunnel end up the same way as the Severn tunnel even with the more modern building technology used in construction?

 

[zwk500]

Will the channel tunnel end up the same way as the Severn tunnel even with the more modern building technology used in construction?

Probably not as the Severn Tunnel issue is related to groundwater (the Great Spring) much more than the River/Estuary itself. Modern hydrographical surveys would hopefully pick up such an obstacle and the tunnel be routed around it.

 

[TheWierdOne]

Will the channel tunnel end up the same way as the Severn tunnel even with the more modern building technology used in construction?

Not for a while, if memory serves correctly the channel tunnel pumping capacity turned out to be significantly overbuilt as the water ingress was much lower than expected. I believe that only a portion of the pumps in the channel tunnel are actually active most of the time.

 

[HSTEd]

Sea depth is as much (arguably more) of a hindrance to a bridge. Especially considering that the Channel is one of the busiest shipping areas in the world. Your bridge deck would need to be high enough to accommodate the largest container ships (and with some room to spare allowing for bigger ships in the future) or have a lifting section which somewhat defeats the object.

No part of the Strait of Dover is deep enough to make a concrete pylon unbuildable, it might somewhat increase the cost though.

As to air draught, yes that is an important driver on bridge design.

But the wide channel actually helps somewhat in that regard.
The gradient necessary to reach the shipping channel at the correct height would be very modest by the standards of bridges on rivers etc.

Also I believe cruise ships are the current driver on air draught.

 

[Sorcerer]

Does the Channel Tunnel boring through a relatively linear layer of chalk marl also play a part in why it probably don't need to worry about water as much as the Severn Tunnel will after the same timespan? Chalk marl is waterproof and only had a few fractures that the tunnellers were able to deal with during construction, so water-logged ground for the most part seems fairly unlikely to be of any concern in the long term.

Though dedicating tunnels to passengers vs freight would mean you wouldn't have to flight the two different types. That might allow more of an improvement than just the raw speed through the tunnel as you would have more flexibility in scheduling either side.

True but the existing tunnel would need to absolutely max out on capacity before that becomes a concern. TVM 430 already allows headways of about 2.5 minutes, but full ETCS could potentially bring that down further.

 

[TheGrew]

To make it more efficient you could run sleds in groups leaving at fixed but frequent intervals, you could even mount the sleds on some sort of guideway, rails if you will, to reduce the energy consumption. You'd want a constant power supply of course to avoid the risk of battery fires, and ideally it would use parts common to transport systems in one or both of France or the UK. Does anyone know of a transport method we could adapt potentially?

I think one of the challenges is that the trains run at intervals. If you could run an individual vehicle-sized 'sled', you could offer a much more turn-up-and-go service. Sure, in practice, you may want to 'flight' sleds close together, and automatic operation could no doubt achieve much smaller distances between vehicles. As someone who has used Eurotunnel a few times, I am convinced you spend at least a third of the journey time loading and unloading at each end. If you could significantly reduce that by effectively making the trains smaller, I think you may be able to improve throughput. The downside would no doubt be people not stopping for time at duty free.

 

[Transilien]

Not for a while, if memory serves correctly the channel tunnel pumping capacity turned out to be significantly overbuilt as the water ingress was much lower than expected. I believe that only a portion of the pumps in the channel tunnel are actually active most of the time.

So will it need to be replaced eventually? If the Severn tunnel can last over a hundred years, then I think the channel tunnel can too.

 

[HSTEd]

I must admit, I'd rather spend the money for a second crossing on a Channel Tunnel gauge railway line to a new Shuttle terminal near the M25/M11 junction.

We are not short of capacity for additional trains through the Tunnel and will not be any time soon.
But if we are forcing people to load their vehicles onto trains anyway, its our only opportunity for a not horrendously uneconomic rolling highway operation that could have other ancillary benefits.

 

[TheWierdOne]

I must admit, I'd rather spend the money for a second crossing on a Channel Tunnel gauge railway line to a new Shuttle terminal near the M25/M11 junction.

We are not short of capacity for additional trains through the Tunnel and will not be any time soon.
But if we are forcing people to load their vehicles onto trains anyway, its our only opportunity for a not horrendously uneconomic rolling highway operation that could have other ancillary benefits.

Certainly there’s a logistical case for having a lorry shuttle terminal further from Folkestone, and also further from Calais on the French side, but whether that would stack up against the cost of building a gauge cleared route is highly questionable.

 

[HSTEd]

Certainly there’s a logistical case for having a lorry shuttle terminal further from Folkestone, and also further from Calais on the French side, but whether that would stack up against the cost of building a gauge cleared route is highly questionable.

You wouldn't just serve lorries I imagine.

I'd expect to be able to sell car shuttles from north of the Thames to Calais too, and if you do eat the cost of such an expensive new route I don't see any reason not to.

 

[mike57]

Certainly there’s a logistical case for having a lorry shuttle terminal further from Folkestone, and also further from Calais on the French side, but whether that would stack up against the cost of building a gauge cleared route is highly questionable.

I had a similar thought, a terminal close to the M25 aound the section between the M11 and the M1, but the costs and problems associated with HS2 pretty much kill off any hope of it ever happening.

 

[jon0844]

You do of course swap the emissions problems for the scenario of a battery fire inside the tunnel. I’m not sure I fancy war-gaming a lithium fire in a confined space with 40 metres of water overhead.

I expect there will be new battery chemistries by then that solve that issue.

Personally, it seems silly to waste power to propel each individual vehicle when we have a train that can carry lots of cars in one go - and, who knows, potentially provide power to charge while in motion.

In other words, let's not bother to build a road tunnel - even if you could run safe EVs that auto drive through. The tech will allow it by then, sure, but do we actually need to do it?

== Doublepost prevention - post automatically merged: 13 Nov 2025 ==

A drive through crossing would likely be a viaduct/bridge rather than a tunnel, which avoids all the associated problems with ventilation and fires.

Of course, with improvements in immersed tube technology, a tunnel may not even be bored.
The Fehmarn Belt fixed link is an ~18km immersed tube, although the seabed is only 35m down there. I believe the Channel is significantly deeper.

Bridges will be impacted by weather, and you would surely just build a road tunnel now to be zero-emission vehicles only. Problem solved.

But I am not convinced we need a road tunnel. There will be accidents. There will be break downs. Nobody wants to be stuck in traffic in a tunnel, and they don't have to be if they're on a high-speed train...

 

[HSTEd]

Bridges will be impacted by weather, and you would surely just build a road tunnel now to be zero-emission vehicles only. Problem solved.

That wouldn't solve the carriage of flammable goods or what to do with a vehicle fire inside the tunnel.
Even the Dartford Tunnels don't allow flammable loads through in general traffic.

As for weather, there are bridges in existence today that remain at least partially open in everything up to a Typhoon.

In Hong Kong they have a cable stay bridge with an enclosed bridge deck used for trains and for providing a lane of traffic in each directions even if the top deck is closed.

But the weather would only very rarely get that bad, and a bridge has advantages in terms of evacuation, fire response and ventilation.

But I am not convinced we need a road tunnel. There will be accidents. There will be break downs. Nobody wants to be stuck in traffic in a tunnel, and they don't have to be if they're on a high-speed train...

Because trains are famous for never breaking down!

The car is here to stay, whether we like it or not.

 

[SynthD]

Well engineering sense depends on the technology in the future.

Are you keeping open the possibility that a longer tunnel under a deeper part of the sea will be cheaper by some future invented method?

The capacity of the existing tunnel would be enormous if it had no speed differential shuttles in the way though.

Yes, if it were low on spare capacity I’d wonder about what sets the speed limits, likely safety, and engineering checks for wear and tear. Does it have its own track monitoring train, or could every shuttle loco do that?

The car is here to stay, whether we like it or not.

That doesn’t tell us whether its wheels are on the ground. The current setup of Shuttle and ferries is solid, reliable and expandable.

 

[D365]

The Severn Tunnel is not really doing well when you need a powerful pump to keep it from not flooding.

Will the channel tunnel end up the same way as the Severn tunnel even with the more modern building technology used in construction?

When the Severn Tunnel was constructed, the builders of the time didn’t have the technology. Pumping has been required more-or-less continuously ever since construction.

 

[FGWHST43009]

Are you keeping open the possibility that a longer tunnel under a deeper part of the sea will be cheaper by some future invented method?

Yes, if it were low on spare capacity I’d wonder about what sets the speed limits, likely safety, and engineering checks for wear and tear. Does it have its own track monitoring train, or could every shuttle loco do that?

That doesn’t tell us whether its wheels are on the ground. The current setup of Shuttle and ferries is solid, reliable and expandable.

Are the Shuttles rated for 140kmh or 160kmh? I think the locos are specced for 160kmh

 

[TheWierdOne]

I had a similar thought, a terminal close to the M25 aound the section between the M11 and the M1, but the costs and problems associated with HS2 pretty much kill off any hope of it ever happening.

Gauge clearing an existing route might be a better shot. You could clear a route as far as Godstone and have a short spur to a terminal adjacent to the M25? Alternatively do gauge clearance to the closest possible point to the lower Thames crossing or the Dartford crossing.