Long tunnels with no ventilation shafts/vice versa

zwk500

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It's also been said that trains don't meet/aren't timetabled together in the tunnel due to the shockwaves.
That condition is next to impossible to guarantee. Given speed is the key to HS1 and the only way to solve this would be to slow 1 train down there's no way it'd be accepted as a timetable planning rule by any party.
 
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Metal_gee_man

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That condition is next to impossible to guarantee. Given speed is the key to HS1 and the only way to solve this would be to slow 1 train down there's no way it'd be accepted as a timetable planning rule by any party.
I agree it seems that way but HS1 isn't at capacity, 2 miles at 186mph is 39 seconds for a Eurostar train to clear the tunnel
Or at 140mph is 51 seconds for a southeastern javelin. Shows it is very possible
 

zwk500

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I agree it seems but HS1 isn't at capacity, 2 miles at 186mph is 39 seconds for a Eurostar train to clear the tunnel
Or at 140mph is 51 seconds for a southeastern javelin. Shows it is very possible
It's entirely possible they don't meet, but it will be by happy accident (or expected coincidence) rather than because trains are deliberated timed apart at the tunnel.
 

Tomnick

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At 2 miles long and the deepest UK tunnel when built, it was an engineering feat for a set of circumstances set.
It’s not the deepest tunnel in the UK, not by a long way. I’m pretty sure that Cowburn Tunnel is*: the depth to rail level at the deepest point is approx 250m - the highest land above the North Downs tunnel isn’t even that far above sea level!

* - standard gauge railway, national network, etc., obviously excluding tunnels in deep mines and the rest
 

Metal_gee_man

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It’s not the deepest tunnel in the UK, not by a long way. I’m pretty sure that Cowburn Tunnel is*: the depth to rail level at the deepest point is approx 250m - the highest land above the North Downs tunnel isn’t even that far above sea level!

* - standard gauge railway, national network, etc., obviously excluding tunnels in deep mines and the rest
At the time the largest cross sectional area excavated and the deepest twin track railway tunnels constructed in the UK in 2001.
In addition it runs under Bluebell Hill one of the highest points in Kent at 183m above sea level
 
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zwk500

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At the time the largest cross sectional area excavated and the deepest twin track railway tunnels constructed in the UK in 2001.
This is almost word-for-word quote from wikipedia, and the reference provided there quotes a depth of 100m. Which is some way short of Cowburn, and probably more tunnels in the Pennines. I don't know on what basis Arup made their claim to the record depth, but they're wrong on the outright record of depth from local ground level. (Either the Channel Tunnel or Severn tunnel being the deepest rail tunnel by lowest altitude, I'm guessing).
In addition it runs under Bluebell Hill one of the highest points in Kent at 183m above sea level
'highest points in Kent' is hardly a benchmark of extremes is it? It'd be like claiming somewhere is the 'sunniest place in Wales'.
 

deltic14

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The new Woodhead had no ventilation shafts as they were not needed!
Not entirely true. For a few years after closure it was possible to walk through the new tunnel. According to eye witness accounts there are two side chambers set into the tunnel walls with shafts going up to the surface....
 

Ashley Hill

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I guess long tunnels under water, such as the Channel and Severn tunnels, don’t have ventilation shafts
The Severn Tunnel has two shafts,one either side of the river. The better known one is the Sudbook Shaft on the Welsh side. A fan at the top ventilates the tunnel. The English vent is hard to spot from a train but it doesn't have a fan.
The two tunnels at Newport have no vents but do have cross passages.
 

Philip

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For basic natural vent shafts in terms of the eerie holes in the tunnel roof with daylight and drips streaming down from the top, I'm guessing neither the London Underground nor the Severn tunnel have these?
 

bramling

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For basic natural vent shafts in terms of the eerie holes in the tunnel roof with daylight and drips streaming down from the top, I'm guessing neither the London Underground nor the Severn tunnel have these?

Most LU shafts for the Tube tunnels take the form of a shaft which comes down between or to one side of the tunnels, and is connected to the tunnels by cross passages. They’re pretty much all iron lined, and the majority will have a large fan somewhere - normally in a small building at the top. There are a small handful of mid-tunnel shafts which don’t have fans.

The openings on the sub surface lines tend to be more varied. ISTR the East London Line has a few brick air shafts which resemble the ones found on mainline tunnels.

As regards the Severn Tunnel, I think the Sea Wall site (on the English side) has two shafts, a simple air shaft and t pump shaft.
 

Ken H

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"Ventilation" shafts were commonly actually left over from the tunnel construction, when it was found more economical to sink vertical shafts down and then dig both ways to meet the next working. Just coming from either end takes much longer. There are all sorts of engineering calculations for the most efficient way to bore it, depth from the surface, access for sinking shafts, etc.
If you walk from Blea Moor box to Dent Heat, you follow the old tramway from when they built the railway. There is a series of spoil heaps along he rail route. Some have ventilation shafts, others have just a heap of rubble. So that shows the number of constructions shafts that were kept and those that were filled in.
As an aside, the vegetation on the spoil heaps is different from the surrounding land. So they have different plants. Including lots of wild strawberries. Yum!
 

Dr_Paul

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ISTR the East London Line has a few brick air shafts which resemble the ones found on mainline tunnels.
Yes: this old map shows some of them. There are some remaining in Dellow Street, according to Streetview.

If you walk from Blea Moor box to Dent Heat, you follow the old tramway from when they built the railway. There is a series of spoil heaps along he rail route. Some have ventilation shafts, others have just a heap of rubble. So that shows the number of constructions shafts that were kept and those that were filled in.
It's much the same with the tunnel north of Blaenau Ffestiniog, with air-shafts along the length of it. I've noticed from the A470 -- no doubt others have too -- a fairly level path linking two of the shafts, which I feel might have been a tramway. Some of the shafts and the path are shown on this map. Some of the shaft tops have sizeable spoil-heaps by them.
 

Annetts key

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You can see some of the vertical air shafts for Chipping Sodbury tunnel, most of which are next to or surrounded by woodland. Search a mapping site / aerial view for Old Sodbury, Bristol and Acton Turville, Badminton.

Box Tunnel also has some vertical air shafts, but apart from one, they are much harder to spot on an aerial view.
 

DPQ

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Slightly off topic, but here's my favourite shaft.
 

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Mikey C

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I walked past today, what I suspected (correctly) was a ventilation shaft, the massive Lisson Green shaft for the Jubilee Line, which is next to the Regent's Canal.


 

Recessio

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The shafts on the Jubilee Extension are huge. Didnt realise a large building was actually a shaft at Canada Water until the rozzers turned up to stop the parkour.

Back in NR land, do the Brighton Main Line (and branches) tunnels have shafts? Oxted and Balcome spring to mind as being old enough to have seen steam services.
 

Mcr Warrior

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Back in NR land, do the Brighton Main Line (and branches) tunnels have shafts? Oxted and Balcome spring to mind as being old enough to have seen steam services.
Seems to be five air / ventilation shafts along the line of the Balcombe tunnel, fairly evenly spaced between the North and South portals.
 

eMeS

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It’s not the deepest tunnel in the UK, not by a long way. I’m pretty sure that Cowburn Tunnel is*: the depth to rail level at the deepest point is approx 250m - the highest land above the North Downs tunnel isn’t even that far above sea level!

* - standard gauge railway, national network, etc., obviously excluding tunnels in deep mines and the rest
Somewhat off topic - My late mother's surname was "Cowburn" - anyone any information as to how the Cowburn tunnel gets its name? Many thanks
 

d9009alycidon

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Most of the tunnels in both the LNER(NBR) and LMS(Caledonian) Glasgow suburban systems followed the line on the roads above and as a result there were few if any ventilation shafts directly above (or at all), indeed the LNER tunnels were closed for a couple of days prior to the introduction of the Blue Trains to allow the smoke to clear from the tunnels. On the main line, Queen Street Tunnel had frequent shafts, but given the gradient and frequency of trains it needed them even into diesel days to clear the acrid fumes .
The Caledonian had an elaborate system on the Argyle Street tunnel to clear smoke from the tunnel, some description and links here https://www.crassoc.org.uk/forum/viewtopic.php?t=140 given all accounts of the Stygian atmosphere at Glasgow Central Low Level and Glasgow Cross Stations it was not that efficient!
 

Gloster

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Somewhat off topic - My late mother's surname was "Cowburn" - anyone any information as to how the Cowburn tunnel gets its name? Many thanks
For the family name try googling (other search engines are available) cowburn etymology for a few suggestions. The tunnel appears to pass under Cowburn or Colborne Moor, but which is older and what the origin is I do not know.
 

tbwbear

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Not entirely true. For a few years after closure it was possible to walk through the new tunnel. According to eye witness accounts there are two side chambers set into the tunnel walls with shafts going up to the surface....
According to the Forgotten Relics website - For Woodhead (3) "The engineer’s plan for three construction shafts was changed in favour of the contractor’s proposal for just one - 16 feet in diameter and located 2,610 yards from the Woodhead end, about 60 yards west of the midpoint."

There is a picture of the shaft under construction.
 

The exile

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Not Crayonista at all. There were plans to join the S&D up with the GW south of Bath, then build a short connecting line across the fields west of Bath to regain the MR route.
Though IIRC those plans would have not involved a new tunnel -“just” rerouting S&D trains via a new spur at Midford to Limpley Stoke and the Bathampton
 

Bald Rick

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I agree it seems that way but HS1 isn't at capacity, 2 miles at 186mph is 39 seconds for a Eurostar train to clear the tunnel
Or at 140mph is 51 seconds for a southeastern javelin. Shows it is very possible

Maths works the other way too. Were this a thing (it’s not) ... If a train is signalled through the tunnel that means one can’t be signalled through the other way. Braking distance at 186mph is around 4km at maximum service braking; allowing for overlaps and driver reaction time etc you are looking at 5km of ‘green signals’ required. Add in the tunnel length, that’s over 8km, which for Javelins is over 2 minutes if they are travelling at full speed, which as we known they often don’t.
 
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eMeS

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For the family name try googling (other search engines are available) cowburn etymology for a few suggestions. The tunnel appears to pass under Cowburn or Colborne Moor, but which is older and what the origin is I do not know.
Many thanks for the suggestion - it's given me some new areas to follow.
 

bramling

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Maths works the other way too. Were this a thing (it’s not) ... If a train is signalled through the tunnel that means one can’t be signalled through the other way. Braking distance at 186mph is around 4km at maximum service braking; allowing for overlaps and driver reaction time etc you are looking at 5km of ‘green signals’ required. Add in the tunnel length, that’s over 8km, which for Javelins is over 2 minutes if they are travelling at full speed, which as we known they often don’t.

Presumably this one can be easily nailed - is there anything in the timetable planning rules which mentions anything regarding this tunnel?
 

Dr_Paul

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Sunderland North tunnel - 575yds long with 5 ventilation shafts visible from google maps!
That seems quite a lot of shafts. There were quite a few on the East London Line, to which I and others referred previously.

Were there any criteria about when to have ventilation shafts in a tunnel? I was reading recently about the problems the LNER had with its Woodhead freight services and the notorious Silkstone tunnel on the heavily graded freight line from Worsborough to Silkstone. The tunnel was fairly short at just under 300 yards, and, so far as I can tell on a 25" map, no ventilation shafts, although it was heavily used by coal traffic, and always had smoke problems which seriously affected the crews of locos, especially those on banking duties (including 'The Garrett' U1). Perhaps it wasn't deemed economic to dig a shaft down 50' or so (judging by contours on OS maps) to give better ventilation, or to open out the tunnel into a cutting.
 

Mcr Warrior

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Somewhat off topic - My late mother's surname was "Cowburn" - anyone any information as to how the Cowburn tunnel gets its name? Many thanks
Local area seems to have had various name changes over the years.

Has been Colborne (1620), Coldborne Moss (1640) and Coldbourne (1725) before reverting back to Colborne.

Cowburn Tunnel was built between 1888 and 1893/4 and has just the one air shaft despite being some 3.3km long. Apparently, when the tunnel was being built, this was from the bottom of the shaft, in two directions, rather than from the ends, as might perhaps have been expected.
 

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