Tunnel Re-boring

[InOban]

Does a tunnel through hard Rock have to have a circular Xsection?

 

[snowball]

Does a tunnel through hard Rock have to have a circular Xsection?

No.

Though obviously any tunnel dug by a rotary TBM has to be circular.

 

[zwk500]

Does a tunnel through hard Rock have to have a circular Xsection?

That would presumably depend on how the various strata were arranged, the strength of the rock in various directions and the size of the void.

 

[The Lad]

In Standedge the current tunnel at each end crosses over the canal tunnel and is a different shape, at the eastern end at least.

 

[quantinghome]

Does a tunnel through hard Rock have to have a circular Xsection?

No, in fact non-circular sections are generally easier in hard rock than in soft material, the difference being that hard rock is essentially self-supporting and the tunnel lining is there to stop loose bits of rock falling off, whereas the tunnel lining in soft material has to support the weight of the ground above it and a circular arch is more structurally efficient.

Of course if you're using a TBM it will be circular no matter what your ground conditions, unless you have one of these:

 

[hwl]

Yes, with a few specialised solutions in places.

Fairly moot, as nobody wants to run a W10/12 through it.

Apart from DfT!

Personally I wouldn't like to have freight on the route and believe Calder valley would probably be better suited for freight. Apart from Miles Platting Jn, I can't remember the gradients on that route. I'm open to being completely wrong!

Completely agree, the Calder Valley may be longer but the gradients are more favorable especially for freight.

 

[InOban]

No, in fact non-circular sections are generally easier in hard rock than in soft material, the difference being that hard rock is essentially self-supporting and the tunnel lining is there to stop loose bits of rock falling off, whereas the tunnel lining in soft material has to support the weight of the ground above it and a circular arch is more structurally efficient.

Of course if you're using a TBM it will be circular no matter what your ground conditions, unless you have one of these:
View attachment 99420

Thanks. I , as a non-engineer, was wondering whether a machine with roof-mounted cutting equipment could widen the roof, so to speak, so that it could accommodate W12 wagons, which are increasingly becoming the standard.

 

[Bald Rick]

Thanks. I , as a non-engineer, was wondering whether a machine with roof-mounted cutting equipment could widen the roof, so to speak, so that it could accommodate W12 wagons, which are increasingly becoming the standard.

Easily. But that would weaken the structural integrity of the structure.

 

[InOban]

I was only suggesting it for proper rock, not the stuff the softies of the SE England call rock! True grit!

 

[Legolash2o]

Completely agree, the Calder Valley may be longer but the gradients are more favorable especially for freight.

I believe there's also less traffic in general and it's better than having to go all the way down to Litchfield Lichfield!

 

[zwk500]

I believe there's also less traffic in general and it's better than having to go all the way down to Litchfield!

Running all the way down to Litchfield may still be preferable than having to sit and wait behind all-shacks local trains at Manchester, and waiting for the path through Man Vic and Salford.

 

[snowball]

I believe there's also less traffic in general and it's better than having to go all the way down to Litchfield!

Or even Lichfield, which is over 100 miles further north than Litchfield, and has the advantage of a railway.

 

[mr_moo]

There's an interesting video about Farnworth tunnel on youtube:

Also, I have some pictures from a talk about Farnworth I attended some years back.

 

[Legolash2o]

Or even Lichfield, which is over 100 miles further north than Litchfield, and has the advantage of a railway.

Oops, I meant Lichfield

 

[edwin_m]

No, in fact non-circular sections are generally easier in hard rock than in soft material, the difference being that hard rock is essentially self-supporting and the tunnel lining is there to stop loose bits of rock falling off, whereas the tunnel lining in soft material has to support the weight of the ground above it and a circular arch is more structurally efficient.

Of course if you're using a TBM it will be circular no matter what your ground conditions, unless you have one of these:
View attachment 99420

Mickey Mouse shaped tunnel for Disneyland?

 

[GC class B1]

Yeah, I can't imagine the route being closed for year. Even six months would be a pain!


You could temporary re-open the closed tunnels next to Standedge but that would definitely add cost to what would be an already expensive project, just to design those lines and do that work (repairing, making sure it's safe, up to standard, etc). That's assuming you can even get the funding.

I am not an expert but having looked at the photographs wouldn’t it be more logical and cost effective to rebore the old two tunnels, perhaps into one large bore. This would eliminate disruption during the work and enable the most cost effective and least time solution.

 

[zwk500]

I am not an expert but having looked at the photographs wouldn’t it be more logical and cost effective to rebore the old two tunnels, perhaps into one large bore. This would eliminate disruption during the work and enable the most cost effective and least time solution.

At Standedge, because of the cross passages between all 4 tunnels, it's highly likely that the cheapest and quickest way to do it would be to build a brand new tunnel (which would also potentially allow realignment at the Marsden end). It would be a new excavation, within a controlled environment and could be designed and built from scratch to today's standards.

 

[Bald Rick]

All the talk of a new tunnel at Standedge is irrelevant. If there’s a new tunnel going to be built there, it will extend a lot further west...

 

[LNW-GW Joint]

All the talk of a new tunnel at Standedge is irrelevant. If there’s a new tunnel going to be built there, it will extend a lot further west...

Nice time to mention that contracts for the 57.5km Mont d'Ambin Base Tunnel (replacing the 1872 Fréjus rail tunnel) between Lyon and Turin have just been let.
The overall project is a snip at €8.6 billion...
Lyon – Torino base tunnel contracts signed | News | Railway Gazette International
Turin–Lyon high-speed railway - Wikipedia

Three major contracts have been awarded for construction of the 57·5 km cross-border Mont Cenis base tunnel, which is central to the programme to develop a high-capacity rail route between Lyon and Torino.

Construction will be a mix of TBM and excavation.
The tunnel maximum design speed is 220km/h, so not quite high speed (it will also carry freight).
On the French side the project also delivers a high speed line Lyon-Chambery and part way to Grenoble.

 

[YorksLad12]

Also, I have some pictures from a talk about Farnworth I attended some years back.

View attachment 99431

That's a fascinating image. Given that you can clearly see one end of the tunnel from the other you might have been able to fill them both in and created one new bore down the middle, in a straight line. You would have had to close the whole route, of course.

 

[61653 HTAFC]

All the talk of a new tunnel at Standedge is irrelevant. If there’s a new tunnel going to be built there, it will extend a lot further west...

Everything that I've heard from people who know what they're talking about suggests that there's nothing about the Standedge tunnel to suggest that wiring it would be a major problem. The main complicating factor is the length- an obstacle that certainly isn't insurmountable.

That's a fascinating image. Given that you can clearly see one end of the tunnel from the other you might have been able to fill them both in and created one new bore down the middle, in a straight line. You would have had to close the whole route, of course.

Given the short distance involved, if you were going to the trouble of blockading the route you may as well have opened the whole thing out rather than re-boring. IIRC there's one property above the tunnel that may have needed compulsory purchase.

 

[Bald Rick]

Everything that I've heard from people that know what they're talking about suggests that there's nothing about the Standedge tunnel to suggest that wiring it would be a major problem.

It isn’t, as most tunnels are not - I’ve been saying that on these pages for years!

 

[61653 HTAFC]

It isn’t, as most tunnels are not - I’ve been saying that on these pages for years!

Well, you are one of those "who know what they're talking about"...

 

[Revaulx]

Everything that I've heard from people that know what they're talking about suggests that there's nothing about the Standedge tunnel to suggest that wiring it would be a major problem. The main complicating factor is the length- an obstacle that certainly isn't insurmountable.

Given the short distance involved, if you were going to the trouble of blockading the route you may as well have opened the whole thing out rather than re-boring. IIRC there's one property above the tunnel that may have needed compulsory purchase.

Yeah I just don’t get what the imagined difficulties of wiring Standedge could possibly be. Sure, there’s a nasty bend at the east end, but that’s an operational hindrance rather than an obstacle to wiring.

Scout Tunnel only has one house above it…

 

[snowball]

Stalybridge tunnel, however, is a major headache according to a couple of items I've read recently.

 

[hwl]

Stalybridge tunnel, however, is a major headache according to a couple of items I've read recently.

Oh no it isn't...

 

[snowball]

Oh no it isn't...

Could you elaborate please?

 

[hwl]

Could you elaborate please?

Sorry not paying attention at my end I thought Standedge had been borough up again!

 

[snowball]

That's twice in three months, in two different threads, that I've said Stalybridge tunnel is a problem, and each time the first reply was from someone who thought I'd said Standedge!

 

[Legolash2o]

Stalybridge tunnel, however, is a major headache according to a couple of items I've read recently.

I agree. I think out of the three tunnels, Stalybridge would be the most difficult one.