How *should* HS2 have been built?

[Bald Rick]

Okay, I must admit, I didn't think of emergency escapes, and having given it more thought I think I should've compared the Chiltern tunnels more to the Alpine base tunnels such as the Gotthard which, while much longer, is also single bore tunnels running great distances, rather than the North Downs Tunnel which is comparatively shorter.

Both the Gotthard base tunnel and the Lötschberg base tunnel are twin tunnels*, as is the new base tunnel being built now - Mont d’Ambin.

* Lötschberg for the part that is twin track.

 

[stuu]

Was there anything safety-related about having single bores? Either just the not banging trains into each other or to facilitate evacuations?

Italy and Germany seem to prefer single bore tunnels, elsewhere in Europe twin bore seems to be the preference

 

[Energy]

Was there anything safety-related about having single bores? Either just the not banging trains into each other or to facilitate evacuations?

Yoi can facilitate evacuations with either, it's more to do with aerodynamics, a 300+kph dual track tunnel would have to be pretty large go cope with the air moving from 2 passing trains.

The costs nowadays seem fairly similar, though getting a 14+m diameter tunnel through London would be difficult.

The HS2 London tunnels could be built to lower speeds without too much affect, you'd just need to be careful as HS2 reuses TBMs.

 

[JamesT]

Was there anything safety-related about having single bores? Either just the not banging trains into each other or to facilitate evacuations?

Italy and Germany seem to prefer single bore tunnels, elsewhere in Europe twin bore seems to be the preference

I don’t know if it quite counts as safety, but two tunnels means you can shut one for maintenance and keep using the other.

 

[Matt P]

I have always thought the former Great Western route through Bordesley, Moor Street, Snow Hill and beyond to Wolverhampton looked like a nice straight line so what a waste it is for trams and trains that could not fit into New Street. Rewind thirty-ish years and it was sitting there unused and so that was the time to build HS2. Hindsight !.

The closure of the Snow Hill to Wolverhampton Low Level line (along with the lines connecting it to Dudley) was, with hindsight, a mistake. The same could also be said for the former Midland route through Greater Manchester. Ideally both routes would still be heavy rail. How, how much capacity the routes would they release from the surviving parallel routes ?

If they had survived they'd probably both serve primarily local traffic at metro style frequencies. Being twin track corridors, there may not be much scope for regional or higher speed trains. That said, the Wolverhampton to Snow Hill line would be a useful alternative route for Cross Country if it had survived and had capacity.

The one advantage the Wolverhampton to Snow Hill line has over the Wolverhampton to New Street line is that the formation looks wide enough in many places to four track, although not without difficulties.

 

[dm1]

The main reason why two single bores with regular cross-passages tend to be preferred for new tunnels is fire safety. If a train catches fire in a twin-track tunnel there's nowhere for passengers to go that is smoke-free, unless you build a separate evacuation tunnel. If you build an evacuation tunnel, then you might as well make it a bit bigger and put the second track in it, gaining all the benefits of simplified maintenance etc.

For shorter or lower-speed tunnels you can get around that using signalling restrictions or more powerful ventilation and/or more frequent ventilation shafts.

Long, high-speed tunnels require very careful design of the safety systems and operating procedures. The Gotthard Base Tunnel has two emergency stations (with platforms) and rescue trains permanently stationed and manned at both ends.

In the Lötschberg Base Tunnel there are strict rules about the order in which freight and passenger trains can be flighted to prevent a passenger train being trapped between two freight trains, and the evacuation plan if a train were to stop in the single-track section literally involves commandeering all the public PostAuto buses serving the towns in the Lötschberg pass and sending them through the uncompleted tunnel bore (which serves as an evacuation tunnel) to pick up the passengers.

I'm assuming the Chiltern tunnels have so many ventilation shafts over such a short distance to cope with 18tphpd without as many operating restrictions. Twin bores will be a key part of that.

 

[Bald Rick]

I'm assuming the Chiltern tunnels have so many ventilation shafts over such a short distance to cope with 18tphpd without as many operating restrictions. Twin bores will be a key part of that.

Almost certainly correct

 

[HSTEd]

I believe London Fire Brigade traditionally require that no more than one train be between a pair of ventilation shafts at any given time, although how much power they have outside london is an interesting question.

The two acceptable routes to building tunnels in the TSI are for passages providing access to a place of safety every ~400m, or access shafts every kilometre.
I can see situations where either option is cheaper.

Of course with very large diameter TBMs, you can put both tracks in a single bore with a dividing wall if you want that will grant the required level of fire resistance.

 

[Technologist]

The big costs for underground train lines are Underground stations, remove the stations (by having them on the surface or fitting then within the diameter of the tunnel) and the cost is significantly cheaper.

It's why Musk building big spaces for Tesla's to load/unload when saying that he can create a "metro" solution for less than normal rail options is going about it the wrong way.

Those big spaces are either on the surface or at most at basement level.

The plus side of the 15 person shuttle using rubber tyres is that it can make a 6m radius turn, climb a 20% grade and accelerate at 0.5g.

Because it operates closer to point to point dwell times are less of an issue because onward passengers are probably only going to go to 1-2 stops max.

Because most of the stations are bypassed they can be a lot more frequent and also don't need to be on the linear trunk route.

 

[HSTEd]

The plus side of the 15 person shuttle using rubber tyres is that it can make a 6m radius turn, climb a 20% grade and accelerate at 0.5g.

Almost any rubber tyre metro system can climb those sorts of gradients and accelerate at those sorts of rates.

 

[Snow1964]

I'm assuming the Chiltern tunnels have so many ventilation shafts over such a short distance to cope with 18tphpd without as many operating restrictions. Twin bores will be a key part of that.

Even at 30 trains per hour (every 2 minutes) trains doing 150mph will be about 5 miles apart. They will be doing 2.5 miles per minute.

They are quite big bore to reduce air pressure piston effect, even when using double deck trains (which aren't envisaged for initial phase)

 

[al78]

Building a surface six lane motorway connecting manchester and sheffield would be almost impossible, you have to tunnel there for practicality concerns, not the same for the Chilterns where the reason for tunnel was purely political pressure.

There were once plans to connect Manchester and Sheffield with the M67 but only a small section on the east side of Gtr Manchester was ever built.

Pathetic Motorways

Examines and pokes fun at some of the lesser known British motorways. Includes photos and videos

pathetic.org.uk

== Doublepost prevention - post automatically merged: 11 Nov 2023 ==

I fully agree that the right to protest is very important, and that banning protest about a specific issue is absolutely unacceptable, and fits better in North Korea than in a democratic country. The government has in fact banned lots of tactics used by HS2 protestors under the public order act 2023, and the possible sentences do include jail time

== Doublepost prevention - post automatically merged: 29 Sep 2023 ==


And that is a clear sign that Australia is moving away from a democratic state and more towards being an authoritarian one

Australia has its own satire channel on YouTube which does a humorous exposure of some of the worst aspects of its government (and on some other countries occasionally as well).

THE JUICE MEDIA

We make Governtment Ads honest. Produced by our Patrons

www.thejuicemedia.com

 

[Snow1964]

From where we are now (as in what is now being built as phase 1), it would be possible to build about 40 extra miles to south of Crewe, and about 40 extra miles towards East Midlands.

Could probably do each for £3-4bn if didn't go in for engineering overkill. Which considering each would extend line by about third doesn't seem that bad value.

Of course what it does demonstrate is once sunk costs into the Expensive line to London, adding few miles across uncongested fields to bypass a bottleneck will have a much higher cost-benefit ratio as stand alone project.

My own feeling is that adding bypass or cut-off sections further north is way forward now. Personally would get to south of Crewe avoiding the 2track bottleneck, then try and get the eastern leg built and connected to Sheffield and Leeds line, perhaps even building cut off around York to get faster to Newcastle and Edinburgh.

 

[HSTEd]

If HS2 Phase 2 truly is dead and we are starting from a blank slate in our current position, I'm not sure the route via Crewe is particularly a good idea any more.
WIth mooted east-west upgrades betwen Manchester and Liverpool, wouldn't it be better to route directly from HS2 Phase 1, east of Stoke on Trent to Manchester Airport?

Trains to Liverpool and Scotland could run to Newton-le-willows/Warrington (for the new line, if built) on a spur.

 

[Bald Rick]

WIth mooted east-west upgrades betwen Manchester and Liverpool, wouldn't it be better to route directly from HS2 Phase 1, east of Stoke on Trent to Manchester Airport?

That depends on whether the Act is repealed or not.

 

[Kingston Dan]

That depends on whether the Act is repealed or not.

Repeal wasn't mentioned in the monarch's speech (and I can't see it getting a majority for repeal particularly in the Lords), but as it is enabling legislation it can be left to lapse. Providing the safeguarding is removed and the purchased properties sold off - that does the job instead.

 

[Energy]

Repeal wasn't mentioned in the monarch's speech (and I can't see it getting a majority for repeal particularly in the Lords), but as it is enabling legislation it can be left to lapse. Providing the safeguarding is removed and the purchased properties sold off - that does the job instead.

Safeguarding removed requires the repeal to go through parliament, the 2a bill has compulsory purchase powers till 2026 and they'd be easy for a future government to extend if needed.

Rishi seems to have found this out after his Network North plan and has (thankfully) gone quiet. Given that GBR struggles to get parliamentary time under him I'd be surprised if he spent any more on undoing HS2.

He's also realised that canceling HS2 enlargened a big divide in his party, he doesn't want a Rishi-rebellion.

 

[Kingston Dan]

Safeguarding removed requires the repeal to go through parliament, the 2a bill has compulsory purchase powers till 2026 and they'd be easy for a future government to extend if needed.

Rishi seems to have found this out after his Network North plan and has (thankfully) gone quiet. Given that GBR struggles to get parliamentary time under him I'd be surprised if he spent any more on undoing HS2.

He's also realised that canceling HS2 enlargened a big divide in his party, he doesn't want a Rishi-rebellion.

That's good to hear.

 

[Peter Sarf]

From where we are now (as in what is now being built as phase 1), it would be possible to build about 40 extra miles to south of Crewe, and about 40 extra miles towards East Midlands.

Could probably do each for £3-4bn if didn't go in for engineering overkill. Which considering each would extend line by about third doesn't seem that bad value.

Of course what it does demonstrate is once sunk costs into the Expensive line to London, adding few miles across uncongested fields to bypass a bottleneck will have a much higher cost-benefit ratio as stand alone project.

My own feeling is that adding bypass or cut-off sections further north is way forward now. Personally would get to south of Crewe avoiding the 2track bottleneck, then try and get the eastern leg built and connected to Sheffield and Leeds line, perhaps even building cut off around York to get faster to Newcastle and Edinburgh.

The £3-4bn extension to Crewe is as much common sense as we should hope for.

I then think, decades later, NPR should be used to extend HS2 to Leeds, forget via the East Mdlands so soon (!).

 

[Technologist]

Almost any rubber tyre metro system can climb those sorts of gradients and accelerate at those sorts of rates.

I don't think you checked my units for acceleration most cars never mind rubber tyred rail vehicles cannot accelerate at 0.5g, it's 0-60 in 5 seconds.

You'd probably want a system to make sure people are sat down before accelerating at such rates. It would be that rather than an engineering limitation that would slow your BEVs down.

 

[YorkRailFan]

Build all of the current phases, as well as a link to HS1 to allow crossborder services from other cities outside of London.

 

[The Planner]

Build all of the current phases, as well as a link to HS1 to allow crossborder services from other cities outside of London.

Build all the phases and you wouldn't have capacity for the link to HS1, which cannot be built anyway.

 

[YorkRailFan]

Build all the phases and you wouldn't have capacity for the link to HS1, which cannot be built anyway.

This is me letting my mind run wild. I think that connecting HS1 and the ECML should be of bigger priority.

 

[Energy]

This is me letting my mind run wild. I think that connecting HS1 and the ECML should be of bigger priority.

Why? Any other station with Eurostar services is going to need the border checks, ECML is already an easy check with Kings Cross and St Pancras being across the road.

 

[YorkRailFan]

Why? Any other station with Eurostar services is going to need the border checks, ECML is already an easy check with Kings Cross and St Pancras being across the road.

To allow direct services to the continent from Leeds, Newcastle and Edinburgh.

 

[Peter Sarf]

This is me letting my mind run wild. I think that connecting HS1 and the ECML should be of bigger priority.

I think for passenger there is not enough demand for through trains from beyond London to Europe that cannot be catered for by a change of trains in London. Bear in mind customs and excise processes take up a lot of space at St Pancras so that would need setting up at other cities.

One day when air travel has ceased then the economics/practicalities might be better. But I think a change of trains might still happen. Otherwise all travellers from (say) Leeds to London regardless of if they are going to Europe would have to go through security. Having a specific train from Leeds to Europe to get round that might mean a very low frequency.

For freight I would hope for a larger (loading gauge) through route beyond London.

 

[YorkRailFan]

I think for passenger there is not enough demand for through trans from beyond London to Europe that cannot be catered for by a change of trains in London. Bear in mind customs and excise processes take up a lot of space at St Pancras so that would need setting up at other cities.

One day when air travel has ceased then the economics/practicalities might be better.

For freight I would hope for a larger (loading gauge) through route beyond London.

Customs could happen at Stratford International, and there is certainly demand for a Birmingham to Continent service.

 

[Peter Sarf]

Customs could happen at Stratford International, and there is certainly demand for a Birmingham to Continent service.

If customes is to happen at Stratford international that implies a change of train. Better to do that at St Pancras with the walk from the adjacent Kings Cross. I wish it was a shorter trip from the very close Euston though. Probably a case for a dedicated rapid mover between Paddington - Euston - StPancras/KingsCross - LiverpoolStreet - overhead monorail/railway/shuttle anyone !. Good luck fitting it in though.

 

[Bald Rick]

This is me letting my mind run wild. I think that connecting HS1 and the ECML should be of bigger priority.

It’s already linked. Direct services are physically possible. Just not politically, or economically.

 

[The Planner]

Customs could happen at Stratford International, and there is certainly demand for a Birmingham to Continent service.

Is there? Based on what?