Should HS2 be a very long tunnel?

[ABB125]

Sorry if this has been discussed elsewhere.

Would it be possible for HS2 to be put in a tunnel all the way from London to the North? Or just for the really sensitive bits such as through the Chilterns? Would it be cheaper/easier/viable?

I would be interested to know your thoughts.

 

[gordonthemoron]

It should be elevated, like the one in Taiwan

 

[civ-eng-jim]

Should it be tunnel? - No. A large proportion of the tunneling on phase 1 is purely for political reasons to appease NIMBYs. It's a real shame that we try to bury so much infrastructure for non-technical reasons.

Could it be tunnel? - Yeah

Cheaper - No. If it were cheaper it would be proposed.

Easier - Probably from a planning point of view but not an engineering view. If there was a continuous stratum of clay all the way then you could probably launch several Tunnel Boring Machines with a skeleton crew. 8 were used on Cross Rail for 42km. so you're looking at nearly 40 for London-Birmingham

Viable - Probably. Although the geology changes greatly from south to north. Different tunneling techniques would be required. Some of which are slower than snail's pace.

Cross passages every 500m would be required - Usually hand/small machine dug (That's 400 in all from London to Birmingham). Intervention/access/ventilation shafts every 1500m or so, or subterranean safe rooms would need to be dug.

I suspect there will be issues with aerodynamics in the tunnels of such length and the bores would need to be even larger to alleviate the "piston" effect.

HS2 guide for tunnelling costs (Excluding the railway systems fit-out)

https://www.gov.uk/government/uploa...file/434516/HS2_Guide_to_Tunnelling_Costs.pdf

 

[ABB125]

I only thought it because I read somewhere that HS2 will be slightly more expensive to build per mile than the new Gotthard base tunnel. That doesn't seem right to me.

 

[HSTEd]

Hard rock tunnelling like that at Gotthard is actually surprisingly cheap - in many cases you can go without any kind of tunnel lining and there are few surprises en route as it is literally a solid block of massive stone.

Near surface tunnelling is far more messy.

 

[WatcherZero]

They way they've kept adding more and more tunnel (either bored or green tunnel) to appease locals, by the time it opens it will be the largest underground in the World.....

 

[Class 170101]

Apparently some tunnelling was cheaper though. Rebuilding the Hanger Lane Gyratory was considered more expensive than just tunnelling underneath it. Nevermind the disruption caused during construction.

 

[Blamethrower]

Apparently some tunnelling was cheaper though. Rebuilding the Hanger Lane Gyratory was considered more expensive than just tunnelling underneath it. Nevermind the disruption caused during construction.

In places like that, yes a tunnel makes sense.

I don't have a problem with a tunnel for most of the way into London, already like that with HS1 and most of London is a sh1II hole anyway so on balance, I prefer looking at a black tunnel wall.

The only thing is line speed in tunnels isn't as fast.

Would be interested to see what the Frankfurt-Cologne NBS does for speeds in tunnels. They are no twin bores, they are all single bores but quite a wide diameter.

Tunnel all the way though? there can't be that many nimbys in this country? oh wait....

 

[Andy-mc]

Biggest cost to this country are "locals" I'm not saying the government should be able to build wherever they want but when the country needs to move forward people need to compromise.
Its like the argument for the extra runway at Gatwick or Heathrow and the more recent proposals for a lower Thames crossing, they are all things that are needed and will inevitably be built in some way, all these protests, enquiries, consultations, etc just delay things that are needed and increase cost, which ultimately is paid by us

 

[HSTEd]

You can build 360km/h tunnels, like the ones in the Chilterns.
The London tunnels are 250km/h because the trains will already be spooling down to stop at the terminus/OOC.

 

[Xenophon PCDGS]

What types of geological strata would the line of this proposed tunnel have to pass through and are there types of strata with a proliferation of springs and the like.

 

[HSTEd]

If the route was entirely in tunnel, construction probably would have started by now.

 

[Xenophon PCDGS]

What would be the envisaged length of the proposed HS2 tunnel? The Gotthard Base Tunnel is 57 kilometres in length.

 

[HSTEd]

There would probably not be a continuous tunnel per say - but a series of multi-kilometre tunnels broken up by 400m long exposed sections that would be long enough to cause the tunnel length to break for escape provision purposes.

 

[Altfish]

As a passenger a long tunnel would be awful. I want to look out of the window and see towns, cities, villages, fields, mountains, rivers not endless monotony. Might as well fly for that.

 

[HSTEd]

As a passenger a long tunnel would be awful. I want to look out of the window and see towns, cities, villages, fields, mountains, rivers not endless monotony. Might as well fly for that.

Most railway lines these days are largely a monotony of tree covered trackside these days.
And 99% of passengers don't really care what is outside of their window these days.

 

[dggar]

Most railway lines these days are largely a monotony of tree covered trackside these days.
And 99% of passengers don't really care what is outside of their window these days.

Do you have a source for this claim?

 

[HSTEd]

Do you have a source for this claim?

No - it is simply personnel observations over large numbers of rail journeys.

 

[Altfish]

Most railway lines these days are largely a monotony of tree covered trackside these days.
And 99% of passengers don't really care what is outside of their window these days.

I don't know which journeys you do but the journeys I do bear no resemblance to your description.

 

[WatcherZero]

I kind of agree and don't agree. The Atherton and Bolton lines pretty much fit that description. Chat Moss line has some nice fields and the fun of racing cars on the Motorway but is mostly uninteresting. The West Coast through the lake district though is absolutely stunning.

 

[Altfish]

I kind of agree and don't agree. The Atherton and Bolton lines pretty much fit that description. Chat Moss line has some nice fields and the fun of racing cars on the Motorway but is mostly uninteresting. The West Coast through the lake district though is absolutely stunning.

I enjoy the approach to the likes of Manchester when you are invariably on a viaduct. Looking at the old industrial landscape and schools and peoples' back gardens.
Even the approach to London Euston looking at the graffiti strewn walls is better than in the numerous tunnels on that route

 

[PR1Berske]

A good old debate for another thread, perhaps. Should passengers have the right to views from the windows or should residents have the right to No trains from their kitchen window?

 

[Blamethrower]

Most railway lines these days are largely a monotony of tree covered trackside these days.
And 99% of passengers don't really care what is outside of their window these days.

These days people use the phrase "these days" too much

 

[LexyBoy]

If we were going to build it in a tunnel, we should do it properly and make it a gravity train. 42 minutes to Manchester, 42 minutes to Leeds, 42 minutes to Birmingham, 42 minutes to OOC...

 

[HSTEd]

These days people use the phrase "these days" too much

People these days don't understand that there are words you can use these days instead of these days.

 

[Ships]

A good old debate for another thread, perhaps. Should passengers have the right to views from the windows or should residents have the right to No trains from their kitchen window?

Trolololol

 

[WatcherZero]

In the old days we said these days all the time.

 

[Class 170101]

And 99% of passengers don't really care what is outside of their window these days.

More like they aren't able to look out of the window as the seat is aligned aith a pillar. The luggage rack gets a better view.

 

[HSTEd]

And do people who aren't enthusiasts really care?
They care about getting to their destination quickly and with the minimum of fuss.

If it was all in a tunnel they would be closer to doing so as construction on Phase 1 would have started years ago.

 

[MonsooN]

I remember Jacob Rees Might saying on Question Time a while ago something like: "The problem in this country is that there's always a newt, or a particle, or a decibel that gets in the way of projects that will be of huge benefit to the rest of the country. Perhaps brexit will help along those lines.

Isn't a huge part of the HS2 budget for legal and compensation costs?

I think it would be disappointing if HS2 was in a tunnel the whole way. The romantic attractions of the railway are speed and power. If you can't see it, it would be a terrible shame.