Grantshouse - Penmanshiel Tunnel avoidance

[Buzby]

For the first time in ages, I’m hurtling down to London KX from Waverley during daylight hours - at the section at Grantshouse the railway takes a (short) realgnment due to the collapse of a tunnel during structural maintenance many years ago. Looking at the topography, and how well the later diversion fitted in to the landscape, I couldn’t fathom why the promoters felt the need to construct an expensive tunnel at this location in the first place when it was so easily avoided subsequently.

Has anyone got an insight into this as it seems odd at first glance!

 

[swt_passenger]

For the first time in ages, I’m hurtling down to London KX from Waverley during daylight hours - at the section at Grantshouse the railway takes a (short) realgnment due to the collapse of a tunnel during structural maintenance many years ago. Looking at the topography, and how well the later diversion fitted in to the landscape, I couldn’t fathom why the promoters felt the need to construct an expensive tunnel at this location in the first place when it was so easily avoided subsequently.

Has anyone got an insight into this as it seems odd at first glance!

I think the simple answer is that the present landscape was re-engineered over a significant distance and is quite different to what existed before the diversion, the diversion’s track position is also significantly higher than the tunnel.

I checked the inspectors report into the accident and it makes no comment on why the original route was chosen. Perhaps they needed to avoid watercourses or the existing road. The A1 was also repositioned to make room for the diversion.

 

[HSTEd]

How big is the cutting? In an era when such structures would have to be excavated by hand, how practical would it's construction be in such a remote location?

 

[Sun Chariot]

Perhaps they needed to avoid watercourses or the existing road. The A1...

I don't have evidence but I do suspect the Great North Road (which became the A1 in 1921) had Right of Way and so the railway surveyors were required to not disrupt it.

(Wikipedia) The Great North Road was the main highway between England and Scotland from medieval times until the 20th century. It became a coaching route used by mail coaches travelling between London, York and Edinburgh

 

[themiller]

If I remember correctly, the tunnel was in the process of being cleared for container trains when the collapse happened. The diversion was constructed using emergency powers and I recall going over the diversion during construction. It was night, there was a speed restriction and there were lights for continuing construction work which was taking place 24/7.

 

[Mcr Warrior]

Anyone able to post a map extract showing the original (tunnel) alignment, and what was built post March 1979?

 

[Sun Chariot]

Anyone able to post a map extract showing the original (tunnel) alignment, and what was built post March 1979?

A quick search on Google: https://www.everand.com/article/426789762/The-Penmanshiel-Tragedy

 

[Mcr Warrior]

A quick search on Google: https://www.everand.com/article/426789762/The-Penmanshiel-Tragedy

Ta. That's quite helpful.

 

[The exile]

If I remember correctly, the tunnel was in the process of being cleared for container trains when the collapse happened. The diversion was constructed using emergency powers and I recall going over the diversion during construction. It was night, there was a speed restriction and there were lights for continuing construction work which was taking place 24/7.

That was presumably right at the end of the construction period. Diversion was via Carlisle (with a few continuing to Euston) or a bus from Berwick to (?) Dunbar.

 

[Railsigns]

Diversion was via Carlisle (with a few continuing to Euston) or a bus from Berwick to (?) Dunbar.

The increase in traffic from the diverted trains created an urgent need to split the long double track section between Carstairs and Midcalder Junction. Less than two months after the tunnel collapse, new stop and distant signals were brought into use on each line to split the section in two at Cobbinshaw. The Up line signals worked automatically within the Midcalder Junction signal box control area, but a temporary Cobbinshaw signal box was opened just to control the Down line signals (C1 and C1R).

 

[yoyothehobo]

Map of the original tunnel route.

I have just found another map which has the area to the west of the original A1 listed as a boggy area as well

 

[The Sleeper]

For the first time in ages, I’m hurtling down to London KX from Waverley during daylight hours - at the section at Grantshouse the railway takes a (short) realgnment due to the collapse of a tunnel during structural maintenance many years ago. Looking at the topography, and how well the later diversion fitted in to the landscape, I couldn’t fathom why the promoters felt the need to construct an expensive tunnel at this location in the first place when it was so easily avoided subsequently.

Has anyone got an insight into this as it seems odd at first glance!

 

[swt_passenger]

This link to NLS maps should give you the ‘slider’ view option from the side by side maps which allows you to clearly see how the contour lines ran, the old 1” map series seems to be clearest for that. Going back to the original question, I suppose taking the foot of the hill away while maintaining a safe slope afterwards would have been a huge task compared to a tunnel:

Side by side georeferenced maps viewer with layer swipe - Map images - National Library of Scotland

 

[The Sleeper]

As an early railways researcher (railarchive.org.uk), I expect the line went where it did due to land owners asking far more compensation than the land was worth. It was quite common for railways to deviate away from the planned route where landed gentry objected or geological challenges which had not been found during the original survey came to light. There was often small land owners who could neither read nor write and there were several agreements for land purchases where the owner just left an X as his mark, even in the 1850's £1.3.4 for two acres and 3 roods was daylight robbery! On the other hand, the gentry and many farmers were well versed in the wilely ways of the railway company land agents, who tried to extract land from them at a well below market value - it would often cost a lot more to deviate rather than reach a settlement and the literate land owners knew this. There is an excellent tale of a farmer who really screwed got the better of the land agents in remote East Anglia.

 

[Buzby]

Thanks all - it would appear that the actual reasoning may be lost in the midsts of time - even boggy ground didn’t seem to phase them, as my local canal F&C was ‘floated’ over Dullatur bog, and the Glw-Edin Railway took a similar route with similar constraints.

Having seen the anguish caused to land owners along the route of HS2 (before revision and cancellation) I don’t think any of them would be boasting at the settlement they received! This was why Penmanshiel stuck in my head as a diversion that could have been avoided in view of the short deviation!

 

[swt_passenger]

Good photo here on Flickr showing the end of the hill cut away before any new growth. I’m no geologist but it looks like a right mess of material…

13/03/1980 - Penmanshiel.

Best viewed Original size. The final visit to Penmanshiel shows the completed new formation by-passing the collapsed tunnel - 13/03/1980.

flic.kr

 

[Deepgreen]

Perhaps a landowner demanded it be hidden from view on his land?

 

[yoyothehobo]

Good photo here on Flickr showing the end of the hill cut away before any new growth. I’m no geologist but it looks like a right mess of material…

13/03/1980 - Penmanshiel.

Best viewed Original size. The final visit to Penmanshiel shows the completed new formation by-passing the collapsed tunnel - 13/03/1980.

flic.kr

The rock is Greywacke, it is generally steeply dipping interbedded, mudstones, siltstones and sandstone. The rock is quite hard, but structurally is a mess and is not the easiest to build a stable cutting slope in, especially when you see just how much hillside has been removed to make the new cutting.

 

[swt_passenger]

The rock is Greywacke, it is generally steeply dipping interbedded, mudstones, siltstones and sandstone. The rock is quite hard, but structurally is a mess and is not the easiest to build a stable cutting slope in, especially when you see just how much hillside has been removed to make the new cutting.

Does that then suggest that the original builders, (given the limited machinery at hand), would have believed it was easier to tunnel than remove?

 

[DelW]

Does that then suggest that the original builders, (given the limited machinery at hand), would have believed it was easier to tunnel than remove?

Tunnelling considerably reduces the volume to be excavated by comparison with open-cut. Miners and bricklayers were (relatively) numerous and cheap to employ in the 19th century, so tunnelling was often more economic than open-cut excavation. In the late 19th century, steam-powered excavation plant changed the economics, which then changed further with widespread use of diesel powered plant in the 20th century.

 

[yoyothehobo]

Does that then suggest that the original builders, (given the limited machinery at hand), would have believed it was easier to tunnel than remove?

To be honest, its probably some of the more difficult stuff to tunnel through in the UK in terms of building a stable tunnel. Its about as far away from London Clay as you can get in terms of suitability!

 

[edwin_m]

To be honest, its probably some of the more difficult stuff to tunnel through in the UK in terms of building a stable tunnel. Its about as far away from London Clay as you can get in terms of suitability!

Sounds similar to Mam Tor in Derbyshire, where a new road was built in (according to Wikipedia) 1819 and struggled on with more and more frequent repairs to landslide damage until closure in the 1970s. Knowledge of geology was probably pretty sketchy in the 19th century, especially if the engineers in question didn't have any familiarity with mining.

 

[Pigeon]

To be honest, its probably some of the more difficult stuff to tunnel through in the UK in terms of building a stable tunnel. Its about as far away from London Clay as you can get in terms of suitability!

It's a bloody mess is what it is... the geology at that particular location is nuts, and not great for building a stable cutting either.

In unstable ground a tunnel is often better than a cutting because you can avoid destabilising the slope by digging away its support at the bottom, and you can build the tunnel as a tubular compressive structure to strongly resist any tendency to movement. Toadmoor tunnel near Ambergate is a good example. This could well have been a consideration at Penmanshiel, and I think it actually was. Modern engineering techniques made getting a good alignment for the "deviation" route more practical than it would have been at the time of the original construction.

In the event the tubular compressive structure bit didn't work out very well because there was a ruddy great cavern above the roof of the tunnel around where it collapsed...

 

[The exile]

Having seen the anguish caused to land owners along the route of HS2 (before revision and cancellation) I don’t think any of them would be boasting at the settlement they received! This was why Penmanshiel stuck in my head as a diversion that could have been avoided in view of the short deviation!

There will be a vast difference between the reactions of landowners who themselves live on and / or farm the land lost to a railway / motorway and those of a remote landlord who may not even be aware where the land is and might even see it as a way to “get back” at a troublesome tenant (talking 19th century here)

 

[Taunton]

It's a similar comparison to the North Staffs line at Harecastle Tunnels, south of Kidsgrove. There were three tunnels, including the most substantial being a mile long. Come electrification in the 1960s and they were abandoned for a diversion just to the west, where a fairly obvious route through an adjacent, closely parallel valley was available. Why ever not go that way to start with.

 

[Stuart21]

If I remember correctly, the new alignment of the railway took over the the old A1 road and a new section of dual-carriageway A1 was constructed. The new rail alignment retains a 60mph limit to the curves.

 

[Sun Chariot]

If I remember correctly, the new alignment of the railway took over the the old A1 road and a new section of dual-carriageway A1 was constructed. The new rail alignment retains a 60mph limit to the curves.

Yes - post #7's info attached here.

 

[Railsigns]

The new rail alignment retains a 60mph limit to the curves.

It's 70 mph.

 

[swt_passenger]

If I remember correctly, the new alignment of the railway took over the the old A1 road and a new section of dual-carriageway A1 was constructed. The new rail alignment retains a 60mph limit to the curves.

As I said in post #2. It’s only partially dualled though, it reduces to a two lane road at the south.

I think the various suggestions about objections from landowners are pure conjecture in this particular case. The more likely reason is there was no room for the railway to be added to the existing gap, and removing the entire hillside would have been too big a job for 19th century navvies.

 

[Gloster]

Although it does strike me that the original course of the line was chosen due to geology or geography, landowners did have considerable influence on the detailed choice of routes. They would use their contacts in the Houses of Commons and Lords to either get bills promoting railways rejected unless their wishes were accommodated or get special clauses inserted which altered or dictated the line’s detailed routing. This seems less likely here as this generally happened if the line was to pass close to their residence, or even close enough for the locos’ smoke to be seen. As the area seems to have been rough moorland it would only be those who were pathologically opposed to railways who would fight it, and then probably in toto, rather than just the detailed route. The owner probably claimed that the area was excellent grazing land and the purchase price should reflect this, rather than scree and bog.