Channel Tunnel capacity

[fandroid]

Interesting and informative discussion. Thanks everyone.

 

[Cloud Strife]

It will be interesting to see what happens when the concession on HS1 and the Chunnel expire. If they return to state control I wonder how they will be run.

The concession runs until 2086 now, but I do wonder if a road tunnel won't eventually be built. 40km Isn't a big deal with modern vehicles and equipment, and with cruise control, it's perfectly reasonable to expect vehicles to go between 80-90 km/h in the tunnel.

If vehicles are released at 5 second intervals and backed up with variable speed limits to slow cars down if needs be, it provides a good safety margin, and it could easily be backed up by having three fire stations within the tunnel itself. The road tunnel idea has two lanes plus a hard shoulder, so with a minimum speed of 80 km/h and a maximum of 100 km/h, it would take no more than 30 minutes end to end.

The only important thing would be to have rest areas every 5-10km so that drivers could stop if they need it, as this would mean no more than roughly 8 minutes between rest areas.

 

[TheWierdOne]

The concession runs until 2086 now, but I do wonder if a road tunnel won't eventually be built. 40km Isn't a big deal with modern vehicles and equipment, and with cruise control, it's perfectly reasonable to expect vehicles to go between 80-90 km/h in the tunnel.

If vehicles are released at 5 second intervals and backed up with variable speed limits to slow cars down if needs be, it provides a good safety margin, and it could easily be backed up by having three fire stations within the tunnel itself. The road tunnel idea has two lanes plus a hard shoulder, so with a minimum speed of 80 km/h and a maximum of 100 km/h, it would take no more than 30 minutes end to end.

The only important thing would be to have rest areas every 5-10km so that drivers could stop if they need it, as this would mean no more than roughly 8 minutes between rest areas.

I believe until electric vehicles (including lorries and vans) are dominant there would be overriding concerns around safety due to air quality. A tunnel that length would require one heck of a ventilation system running constantly. The other issue I believe that was realised during the original construction was that a road tunnel with repetitive features over that distance could run the risk of highway hypnosis, causing accidents.

On the concession length, why in the everloving frogs leg are we permitting critical national infrastructure to be under private control for that amount of time?

 

[zwk500]

The concession runs until 2086 now, but I do wonder if a road tunnel won't eventually be built. 40km Isn't a big deal with modern vehicles and equipment, and with cruise control, it's perfectly reasonable to expect vehicles to go between 80-90 km/h in the tunnel.

If vehicles are released at 5 second intervals and backed up with variable speed limits to slow cars down if needs be, it provides a good safety margin, and it could easily be backed up by having three fire stations within the tunnel itself. The road tunnel idea has two lanes plus a hard shoulder, so with a minimum speed of 80 km/h and a maximum of 100 km/h, it would take no more than 30 minutes end to end.

None of that would be enforceable without a remote operation system.

The only important thing would be to have rest areas every 5-10km so that drivers could stop if they need it, as this would mean no more than roughly 8 minutes between rest areas.

The tunnel is 50km long, that's 10-20 rest areas. The costs would be astronomic.

A tunnel for road traffic is only likely to be viable from a safety perspective if the vast majority of cars are at least partially autonomous.

 

[NCT]

It's easier to change the law than to change the laws of physics...

 

[Cloud Strife]

None of that would be enforceable without a remote operation system.

It's already in place in the Mont Blanc Tunnel and has been for years. They automatically detect violations such as coming too close to the car in front and issue fines accordingly. With modern technology, you can easily illustrate the required gaps and adjust speed limits if the traffic becomes too heavy. All of this is easily achievable.

The tunnel is 50km long, that's 10-20 rest areas. The costs would be astronomic.

No, not so long. The current Channel Tunnel is around 38.5km under water, and any road tunnel can have a significant steeper grade on entry and exit. With 40km, you'd only need a rest area at 10km, 20km and 30km, or ideally 8km, 16km, 24km and 32km. These rest areas don't have to be anything special, it's enough to have a cavern with enough parking spaces for 10-15 cars at the most, as the only purpose is to give people a quick break and to break up the monotony of the tunnel.

A tunnel for road traffic is only likely to be viable from a safety perspective if the vast majority of cars are at least partially autonomous.

From a safety perspective, there's really not much difference between the 24km Laerdal Tunnel and a 40km Channel Tunnel. In fact, any road Channel Tunnel is likely to be safer by virtue of having two lanes in each direction plus a hard shoulder, whereas Laerdal has one lane in each direction with an AADT of 1000 off-season, rising to 2000-3000 during summer. Each shuttle in the Channel Tunnel currently carries up to 120 cars and 12 coaches, so that gives 500 vehicles an hour for the road tunnel - essentially one car every 7.2 seconds, or one car every 180m. With two lanes, you could easily increase this to 1000 safely enough.

 

[signed]

but I do wonder if a road tunnel won't eventually be built

I doubt it, the toll cost will be absolutely massive because of the safety systems that would be needed.

A bridge akin to the HZMB (Hong-Kong/Zuhai/Macau bridge), which is around the same length as a CT road tunnel (it has a 22km bridge portion and 7km tunnel portion) would be much more realistic (because the HZMB exists) and much more nicer to drive on though will be subject to the weather conditions.

 

[Cloud Strife]

On the concession length, why in the everloving frogs leg are we permitting critical national infrastructure to be under private control for that amount of time?

Essentially because it's not really under private control, but rather it's quite strictly controlled by both national governments through the concession. Many of the things that the tunnel currently benefits from, such as the juxtaposed controls, could easily be reversed if Getlink had strange ideas.

 

[Bald Rick]

With 40km, you'd only need a rest area at 10km, 20km and 30km,

Personally I’m not sure having places in the tunnel where you are allowed to stop in a non emergency is a good thing.

I doubt it, the toll cost will be absolutely massive because of the safety systems that would be needed.

The safety systems would be a tiny, tiny fraction of the cost.

A bridge akin to the HZMB (Hong-Kong/Zuhai/Macau bridge), which is roughly the same length as a CT road tunnel (it has a 22km bridge portion and 7km tunnel portion) would be much more realistic (because the HZMB exists) and much more nicer to drive on though will be subject to the weather conditions.

But yes, this will be the answer if it happens. As per the Euroroute proposal in the 1985 competition which Eurotunnel won.