Kilsby and Watford tunnels

[Philip]

Would it be possible to open out the tunnels at Kilsby and Watford into cuttings, or at least, could they have originally been dug as cuttings?

Some tunnels were such because the landowner at the time didn't want the railway passing over the land, even though they were shallow enough to have been dug as a cutting. I don't know about Watford but Kilsby doesn't look very deep, going by the depth of the huge ventilation shafts which give a brief glimpse of the sky. Could both of these have been cuttings?

Also, if shallow enough, would it be financially viable to potentially open out Kilsby and Watford, given the long term savings in not having the tunnel maintenance costs?

 

[Bald Rick]

Also, if shallow enough, would it be financially viable to potentially open out Kilsby and Watford, given the long term savings in not having the tunnel maintenance costs?

What tunnel maintenance costs?

 

[swt_passenger]

What tunnel maintenance costs?

I expect the fairly massive embankments needed to confirm to modern standards would be pretty wide at Kilsby, and they’d have their own maintenance and drainage issues. I think “leave well alone” would be the answer there.

But how would it ever be considered ok to demolish all the existing properties above Watford Tunnels?

 

[Magdalia]

Looking at the Ordnance Survey, I reckon that the trackbeds in Kilsby and Watford tunnels are roughly 30 metres/100 feet below ground level. That's a lot of rock and soil for Victorian navvies to dig out with picks and shovels.

Nearby is the Great Central London Extension, built in the early 20th century, when construction techniques had advanced considerably. But the GCLE still went through the watershed in a tunnel at Catesby.

 

[Bald Rick]

I expect the fairly massive embankments needed to confirm to modern standards would be pretty wide at Kilsby, and they’d have their own maintenance and drainage issues. I think “leave well alone” would be the answer there.

But how would it ever be considered ok to demolish all the existing properties above Watford Tunnels?

well quite - there’s at least £100m of real estate above Watford tunnels alone.

 

[stuu]

Even by occasionaly arcane standards of this forum, this is a weird suggestion. They are closing in on their 200th birthday, I think the time for change is somewhat behind them

 

[AlastairFraser]

Would it be possible to open out the tunnels at Kilsby and Watford into cuttings, or at least, could they have been originally dug as cuttings?

Some tunnels were such because the landowner of the time didn't want the railway passing over the land, even though they were shallow enough to have been dug as a cutting. I don't know about Watford but Kilsby doesn't look very deep, going by the depth of the huge ventilation shafts which give a brief glimpse of the sky. Could both of these have been cuttings?

Also, if shallow enough, would it be financially viable to potentially open out Kilsby and Watford, given the long term savings in not having the tunnel maintenance costs?

Watford and Kilsby tunnels are relatively straight, so there is no reason to open them out as the cost of opening them out would exceed the savings for decades.
Linslade tunnel might be a good idea to cut and cover though to straighten and increase line speeds through the area, the worksite could be replanted afterwards.
Apart from that, the only worthwhile WCML improvements in my opinion would be reinstatement/building of 4 tracks the whole way Preston to Springs Branch Jcn to improve resilience of this section especially if HS2 will be using this from Crewe to further north for the time being, plus grade separation of Slade Lane Jcn to remove this pinchpoint. Although that's a big ticket item!

 

[childwallblues]

Shugborough Tunnel south of Stafford is more of a problem being only two track from Colwich to Milford and Brocton.

 

[4F89]

Shugborough Tunnel south of Stafford is more of a problem being only two track from Colwich to Milford and Brocton.

Not exactly a long section of track though, barely worth even considering.

 

[The Planner]

Not exactly a long section of track though, barely worth even considering.

It will be if HS2 2a gets canned. People will be looking at that and Colwich and going "hmmm"

 

[Philip]

Looking at the Ordnance Survey, I reckon that the trackbeds in Kilsby and Watford tunnels are roughly 30 metres/100 feet below ground level. That's a lot of rock and soil for Victorian navvies to dig out with picks and shovels.

Nearby is the Great Central London Extension, built in the early 20th century, when construction techniques had advanced considerably. But the GCLE still went through the watershed in a tunnel at Catesby.

I would say the cuttings at Blisworth and Tring are close to 100ft below ground level. Opening the tunnels out would seemingly not be cost effective, but to go to the original question; are Watford and Kilsby shallow enough to have been dug as cuttings originally? And what about the 'modern' Disley Tunnel on the New Mills-Hazel Grove line?

What tunnel maintenance costs?

Inspections, brickwork repairs to the roof/portal/sides/shafts, drainage repairs to name some.

 

[The Planner]

I would say the cuttings at Blisworth and Tring are close to 100ft below ground level. Opening the tunnels out would seemingly not be cost effective, but to go to the original question; are Watford and Kilsby shallow enough to have been dug as cuttings originally? And what about the 'modern' Disley Tunnel on the New Mills-Hazel Grove line?



Inspections, brickwork repairs to the roof/portal/sides/shafts, drainage repairs to name some.

Sorted the drainage out in the big blockades over COVID.

 

[Dr Hoo]

I would say the cuttings at Blisworth and Tring are close to 100ft below ground level. Opening the tunnels out would seemingly not be cost effective, but to go to the original question; are Watford and Kilsby shallow enough to have been dug as cuttings originally? And what about the 'modern' Disley Tunnel on the New Mills-Hazel Grove line?



Inspections, brickwork repairs to the roof/portal/sides/shafts, drainage repairs to name some.

Judging by the massive problems with flooding and landslips in many cuttings, with remediation costs in the tens of millions it isn’t at all clear that the alternative is any cheaper. Obviously activities like inspection and drainage maintenance are needed for all civil engineering features. Carmont is a recent case in point.

 

[SargeNpton]

Nearby is the Great Central London Extension, built in the early 20th century, when construction techniques had advanced considerably. But the GCLE still went through the watershed in a tunnel at Catesby.

Catesby should have been a cutting, but the local landowner insisted on a tunnel to preserve his view of the landscape.

 

[Bald Rick]

Inspections, brickwork repairs to the roof/portal/sides/shafts, drainage repairs to name some.

all of which happen with cuttings (albiet With soil rather than brickwork).

 

[Dr Hoo]

Catesby should have been a cutting, but the local landowner insisted on a tunnel to preserve his view of the landscape.

Do you have a source for this?

The tunnel only runs under the landowner's 'park' at its northern end. As an 'accommodation' there were no shafts in the first 500 yards of the c. 3,000-yard tunnel.

The geology changes markedly part way through the tunnel with the northern end through a very heavy lower lias that was prone to movement. The remaining 2,500 yards were through a lighter middle lias and was built at an amazing 110 yards per month with full-sized headings from nine working shafts. It was claimed as a record for tunnel building of its type - scarcely over 27 months from breaking ground to completion!

Why would a cutting be preferred when most of it was so easy?

(Basis for my comments is The Making of a Railway by L T C Rolt and British Railway Tunnels by Alan Blower.)

 

[furnessvale]

Not exactly a long section of track though, barely worth even considering.

It may not be a long section. but I spend many hours there on my canal boat and the number of trains, both passenger and freight, that are checked or stopped there is amazing.

 

[SargeNpton]

Do you have a source for this?

The tunnel only runs under the landowner's 'park' at its northern end. As an 'accommodation' there were no shafts in the first 500 yards of the c. 3,000-yard tunnel.

The geology changes markedly part way through the tunnel with the northern end through a very heavy lower lias that was prone to movement. The remaining 2,500 yards were through a lighter middle lias and was built at an amazing 110 yards per month with full-sized headings from nine working shafts. It was claimed as a record for tunnel building of its type - scarcely over 27 months from breaking ground to completion!

Why would a cutting be preferred when most of it was so easy?

(Basis for my comments is The Making of a Railway by L T C Rolt and British Railway Tunnels by Alan Blower.)

Scroll down to the Heritage section...

https://catesbytunnel.com/thetunnel/

A search of the internet will find other references to it.

 

[AndrewE]

Judging by the massive problems with flooding and landslips in many cuttings, with remediation costs in the tens of millions it isn’t at all clear that the alternative is any cheaper. Obviously activities like inspection and drainage maintenance are needed for all civil engineering features. Carmont is a recent case in point.

Given the drainage and stability issues in cuttings (admittedly mostly built decades or centuries ago) and the current state of TBMs I wonder whether the balance has shifted between which is cost effective? The old books say at 60 feet of cover, I think, but nowadays a sealed (waterproof) concrete tube installed behind the machine might be justified at much shallower depths.
It might even be worth de-cuttingising some lines, although that wasn't so good at Gerrads Cross! (https://en.wikipedia.org/wiki/Gerrards_Cross_Tunnel) Maybe if that had been 2 stronger tubes it would have worked better.

 

[Dr Hoo]

Scroll down to the Heritage section...

https://catesbytunnel.com/thetunnel/

A search of the internet will find other references to it.

Thank you for the reply, although I am still far from convinced. The landowner at the time - a jeweller and pawnbroker in London by the name of Henry Attenborough - doesn't appear to have had any particular political heft and there is plenty of ancestry and architectural history about the family and Catesby Hall at the end of the 19th Century that doesn't even mention the railway or tunnel.

Anyway, this is rather OT for @Philip 's question about whether Kilsby and Watford should be opened out so I'll leave it there and do not propose to start a new 'History' thread.

 

[Bald Rick]

de-cuttingising

New forum word of the Year!

 

[Philip]

Would anyone know the deepest point of Kilsby, Watford and Disley and based on this whether a cutting would have been realistically possible when dug in the first place?

 

[zwk500]

Would anyone know the deepest point of Kilsby, Watford and Disley and based on this whether a cutting would have been realistically possible when dug in the first place?

As the original builders chose not to, perhaps the answer is staring us in the face?

EDIT: 1 of the shafts is 132 feet (c.40m) deep. The average depth is quoted as 120 feet, and the tunnel is more than 2km long. https://www.railengineer.co.uk/stairway-to-heaven-shaft-repairs-at-kilsby-tunnel/

 

[NoRoute]

Given the drainage and stability issues in cuttings (admittedly mostly built decades or centuries ago) and the current state of TBMs I wonder whether the balance has shifted between which is cost effective? The old books say at 60 feet of cover, I think, but nowadays a sealed (waterproof) concrete tube installed behind the machine might be justified at much shallower depths.
It might even be worth de-cuttingising some lines, although that wasn't so good at Gerrads Cross! (https://en.wikipedia.org/wiki/Gerrards_Cross_Tunnel) Maybe if that had been 2 stronger tubes it would have worked better.

Quite, the Watford tunnels and steep cuttings are an interesting example because there was a land-slip resulting in a derailment back in 1940, killing one person and injuring six. Fast forward to 2016 and a landslip occurred at the same location, derailing a train which collided with another train, fortunately with no fatalities but could have been a lot worse.

 

[Peter Sarf]

Looking at the Ordnance Survey, I reckon that the trackbeds in Kilsby and Watford tunnels are roughly 30 metres/100 feet below ground level. That's a lot of rock and soil for Victorian navvies to dig out with picks and shovels.

Nearby is the Great Central London Extension, built in the early 20th century, when construction techniques had advanced considerably. But the GCLE still went through the watershed in a tunnel at Catesby.

Furthermore HS2 still seems to rely on this old trick for dealing with land in the way. And it might even be for the same aesthetic reasons if not practical reasons.

Watford and Kilsby tunnels are relatively straight, so there is no reason to open them out as the cost of opening them out would exceed the savings for decades.
Linslade tunnel might be a good idea to cut and cover though to straighten and increase line speeds through the area, the worksite could be replanted afterwards.
Apart from that, the only worthwhile WCML improvements in my opinion would be reinstatement/building of 4 tracks the whole way Preston to Springs Branch Jcn to improve resilience of this section especially if HS2 will be using this from Crewe to further north for the time being, plus grade separation of Slade Lane Jcn to remove this pinchpoint. Although that's a big ticket item!

My bold. Could even straighten out that section with a new tunnel.

 

[SCDR_WMR]

Shugborough Tunnel south of Stafford is more of a problem being only two track from Colwich to Milford and Brocton.

Colwich junction is awkward, wouldn't mind it being ripped out and made fully useful for all lines. Would also be good if LNR could bring back the Euston service that went via Hixon as an additional

 

[AlastairFraser]

My bold. Could even straighten out that section with a new tunnel.

You could do, but likely it might destabilise the long-established soil formations in the area; (as far as I know, I'm no tunnel expert so maybe other forum members with experience in this area could chip in?)
Better to cut and cover it to future proof it and perhaps widen the loading gauge.
It isn't under the section of the ancient woodland according to the managing Trust, just 1990s plantation on top of the tunnel.

 

[zwk500]

You could do, but likely it might destabilise the long-established soil formations in the area; (as far as I know, I'm no tunnel expert so maybe other forum members with experience in this area could chip in?)
Better to cut and cover it to future proof it and perhaps widen the loading gauge.
It isn't under the section of the ancient woodland according to the managing Trust, just 1990s plantation on top of the tunnel.

Cut and cover would require removal of all the soil and replacing it so would be much worse for the soil formations than a bored tube of soil with local settlement. You'll never put the soil back on top the same way it came out, and disturbance is the biggest issue.

 

[Magdalia]

I would say the cuttings at Blisworth and Tring are close to 100ft below ground level. Opening the tunnels out would seemingly not be cost effective, but to go to the original question; are Watford and Kilsby shallow enough to have been dug as cuttings originally?

I did look at Tring before making my original comment.

I do wonder if this is due to geology, Tring being chalk. Victorian engineers did seem to prefer cuttings to tunnels when going through chalk ridges, is that because of its permeability and consequent drainage issues?

Cut and cover would require removal of all the soil and replacing it so would be much worse for the soil formations than a bored tube of soil with local settlement. You'll never put the soil back on top the same way it came out, and disturbance is the biggest issue.

A few ago, in my commuting days, I was able to watch progress on construction of a "cut and cover" tunnel almost daily. That was the Baldock bypass road tunnel that can be seen from the train. It started by digging a huge cutting in the chalk ridge, followed by laying two massive concrete pipes to take the road, then filling it all in again. I expect that the concrete pipes are sealed to prevent ingress of water.

It is my solution for Chapel Hill near Haslingfield on East West Rail.

And, on a historical note, Warren Hill Tunnel at Newmarket is chalk and was also constructed by "cut and cover".

 

[zwk500]

I did look at Tring before making my original comment.

I do wonder if this is due to geology, Tring being chalk. Victorian engineers did seem to prefer cuttings to tunnels when going through chalk ridges, is that because of its permeability and consequent drainage issues?

Also stability, I'd have thought. Chalk crumbles easily, so tunnelling through it requires care. The Cuttings at the north end of the Quarry and Merstham Tunnels on the Brighton Mainline are a remarkable depth.

A few ago, in my commuting days, I was able to watch progress on construction of a "cut and cover" tunnel almost daily. That was the Baldock bypass road tunnel that can be seen from the train. It started by digging a huge cutting in the chalk ridge, followed by laying two massive concrete pipes to take the road, then filling it all in again. I expect that the concrete pipes are sealed to prevent ingress of water.

It is my solution for Chapel Hill near Haslingfield on East West Rail.

And, on a historical note, Warren Hill Tunnel at Newmarket is chalk and was also constructed by "cut and cover".

Cut & Cover is a well-used method, I think quite a few of the 'environmental' tunnels on HS2 are using it. As well as the Sub-surface tube lines, almost all are Cut and Cover. I was just making the point that Cut and cover is more disturbing to local soil conditions than boring.