Cross passage north of Brixton - Pulross Rd vent shaft?

[Alight]

The other day my Victoria line train waited outside the crossover on the southbound, as it quite often does while awaiting platform availability. On this occasion I happened to be standing at the first right-hand set of double doors in the fourth car in direction of travel; when peering through the window, the train on the adjacent northbound illuminated a cross passage. I wondered if this was the Pulross road shaft but I am not sure it is, as I'd have thought the opening for that is the one slightly farther up the line (which I've never stopped by but can be spotted because sometimes the light has been left on, though blink and you'll miss it!) Or does the Pulross road shaft have two openings (albeit roughly a train length apart?) If not, what is the purpose of this cross passage?

I have tried to see how these appear from a driver eye view in the following video:
<<rincew1nd: video removed>>

There appears to be crossover/vent openings at:
27:22 (closer to Stockwell)
28:48
29:02

Unfortunately the video doesn't go all the way to Brixton, but my assumption is that 29:02 is the opening I spotted from on board the train from which I could see into the cross passage as the northbound train passed and illuminated it.

[quex]

It's not all that unusual to have cross passages, just big enough to walk through, between parallel running tunnels - both for running cables through and access for workers as it saves a long walk round!

It could be one of those you saw as there appears to be one under the top end of Hubert Grove, about a train length from Pulross Road - you can see it on TfL's (publicly available) Property Asset Database Map:

link

[Alight]

Thank you very much. Going by the asset map, I suspect the opening I saw must have been the Pulross road shaft and the opening farther up must be the cross passage level with the top of Hubert street, which from a passing train appears to be currently lit up for some unknown reason!

[North End]

Apr 6, 2021 19:21:17 GMT Alight said:

The other day my Victoria line train waited outside the crossover on the southbound, as it quite often does while awaiting platform availability. On this occasion I happened to be standing at the first right-hand set of double doors in the fourth car in direction of travel; when peering through the window, the train on the adjacent northbound illuminated a cross passage. I wondered if this was the Pulross road shaft but I am not sure it is, as I'd have thought the opening for that is the one slightly farther up the line (which I've never stopped by but can be spotted because it contains a switched-on light, though blink and you'll miss it!) Or does the Pulross road shaft have two openings (albeit roughly a train length apart?) If not, what is the purpose of this cross passage?

I have tried to see how these appear from a driver eye view in the following video:
<<rincew1nd: video removed>>

There appears to be crossover/vent openings at:
27:22 (closer to Stockwell)
28:48
29:02

Unfortunately the video doesn't go all the way to Brixton, but my assumption is that 29:02 is the opening I spotted from on board the train from which I could see into the cross passage as the northbound train passed and illuminated it.

The Vic has a lot of cross passages. Some of these are intermediate fan shafts, however there’s also plenty of former construction sites where there might be a cross-passage or two complete with the remains of an infilled former construction shaft. Especially south of Victoria there’s quite a few.

From a civil engineering point or view the most interesting lines are (IMO) the Northern, Jubilee and Victoria. The Vic is a lot more interesting than its simple route on the Tube Map might initially suggest!

[Alight]

Apr 6, 2021 22:30:19 GMT North End said:

The Vic has a lot of cross passages. Some of these are intermediate fan shafts, however there’s also plenty of former construction sites where there might be a cross-passage or two complete with the remains of an infilled former construction shaft. Especially south of Victoria there’s quite a few.

Thanks North End. For the intermediate fan shafts, do these include emergency escape up to the head-house? I'm always surprised by how big some of the head-house buildings are, particularly the one at the end of the running lines at Somerleyton Road.

[superteacher]

This message has been moved to Deleted Threads by superteacher.

We are checking whether the cab ride video posted is within the forum rules.

[rincew1nd]

Admin comment

Forum Staff have reviewed this thread and in particular the cab-ride video contained in the original post. We do not believe this was an authorised cab-ride and have therefore removed it.

The discussion so far has been interesting though, please continue!

[slugabed]

"From a civil engineering point or view the most interesting lines are (IMO) the Northern, Jubilee and Victoria. The Vic is a lot more interesting than its simple route on the Tube Map might initially suggest!" (North End)

Yes indeed...My understanding is that various sections were built using different tunnelling methods by way of comparison.
I have also heard,which may be an urban myth,or a misunderstanding of the above,that the Vic incorporated some earlier,pre-existing tunnels in its construction...no truth in that? Surely?

[North End]

Apr 7, 2021 9:23:27 GMT Alight said:

Apr 6, 2021 22:30:19 GMT North End said:

The Vic has a lot of cross passages. Some of these are intermediate fan shafts, however there’s also plenty of former construction sites where there might be a cross-passage or two complete with the remains of an infilled former construction shaft. Especially south of Victoria there’s quite a few.

Thanks North End. For the intermediate fan shafts, do these include emergency escape up to the head-house? I'm always surprised by how big some of the head-house buildings are, particularly the one at the end of the running lines at Somerleyton Road.

In general the answer is very much no.

However, there is of course the Netherton Road shaft which is setup as an escape location, and has always been so since day one. There’s a couple of other fan shafts on the Vic Line which I believe are set up for man access, though for security reasons it’s probably best I don’t post which ones. I’ve no idea what they actually contain (the ones concerned happen to be on the only section of Vic Line which I’ve never had the opportunity to explore at track level!), but going by what exists elsewhere I’d suggest it’s probably something like a small metal spiral staircase.

The size of the head house will generally be for two reasons - firstly the tunnel fans are quite large, and secondly because the tower needs to be taken up to whatever is the prevailing roof level.

[North End]

Apr 7, 2021 22:24:12 GMT slugabed said:

"From a civil engineering point or view the most interesting lines are (IMO) the Northern, Jubilee and Victoria. The Vic is a lot more interesting than its simple route on the Tube Map might initially suggest!" (North End)

Yes indeed...My understanding is that various sections were built using different tunnelling methods by way of comparison.
I have also heard,which may be an urban myth,or a misunderstanding of the above,that the Vic incorporated some earlier,pre-existing tunnels in its construction...no truth in that? Surely?

Yes there is some truth in it. Firstly there were two experimental tunnels built from Finsbury Park to Netherton Road, which were essentially trial tunnels for the Victoria Line construction methods. They were specifically built on the proposed Victoria Line alignment. Two of the three working sites were incorporated into the Victoria Line as permanent shafts, as well as the full length of both tunnels.

Secondly there was some use of other lines tunnels at both Finsbury Park and Highbury - at Finsbury Park the s/b Victoria Line platform is the former s/b Northern Line, whilst the n/b Victoria Line platform is the former w/b Piccadilly Line. Likewise at Highbury the s/b Victoria Line platform is the former n/b Northern Line. The s/b Victoria Line also uses a long(ish) section of the former s/b Northern Line running tunnel from Finsbury Park towards Drayton Park. The former n/b Northern Line running tunnel remains unused alongside that, cross passages connect with it. From memory the unused Northern Line tunnel still contains track, and is intact all the way to where the Drayton Park tunnel mouth used to be. Not somewhere ever likely to be open for visits I’m afraid, as both ends are trackside.

The section of 16-ft diameter Northern Line tunnel used by the Victoria Line south of Finsbury Park can clearly be seen on the Video 125 cab ride. The point where the tunnel transitions back to “new” Victoria Line construction can also be felt as a passenger, as the change of tunnel diameter tends to result in ears popping.

[slugabed]

Thank you for the fulsome answer,North End....that explains an awful lot.

[jimbo]

I believe the two sections of trial tunnel north of Finsbury Park were intended to define post-war tunnelling costs to help with construction estimates. One had traditional cast iron linings and the other experimental concrete linings. However, this was all one tunnelling run connected to the southbound Northern City terminal road, and the first test trains to measure noise effects were Standard Stock trains from Drayton Park depot. I recall this from an early British Transport Films documentary. It became the southbound Victoria line, diverted south of Finsbury Park to a new alignment. The connections there with the Piccadilly line are sited where the reversing crossovers south of the platforms existed when these were both deep level terminal stations.

Once the first stage of the Victoria line opened, Northumberland Park depot was filled with trains for the complete line, whilst a dispute at Acton Works resulted in a shortage of 1938TS on other lines. Consideration was given to working 1967TS manually on the Northern City Line to release the 1938TS to more important lines. The Victoria line trains would have been maintained at Northumberland Park depot and transferred through the Drayton Park connection. This unfortunately never came to pass, but was detailed in Underground News some years back.

Before the Victoria line upgrade, Metronet removed redundant rail through this same tunnel connection to Drayton Park for disposal by road, so it must have still existed maybe 15 years back.

[superteacher]

THREAD SPLIT:

Posts about the tunnels between Finsbury Park and Drayton Park have been moved to the thread below:

districtdavesforum.co.uk/thread/32160/tunnels-finsbury-park-drayton

[Alight]

Thanks all for your informative responses and also the continuation of some of the interesting discussion about the Drayton Park - Finsbury Park tunnels - one thing's for sure, I really hear/feel the gust of air whenever I travel past this stretch on the Victoria line, as they serve as natural ventilation... arguably more effective than some of the purpose-built intermediate fan shafts, many of which you don't hear/feel when the train goes past them (maybe because the fans are switched off these days?) I know there were some complaints about the Pulross Road shaft when the fans were upgraded back in '09: brixtonblog.com/2019/12/resident-protest-sees-giant-brixton-fan-switched-off/?cn-reloaded=1

Apr 7, 2021 22:30:48 GMT North End said:

In general the answer is very much no.

However, there is of course the Netherton Road shaft which is setup as an escape location, and has always been so since day one. There’s a couple of other fan shafts on the Vic Line which I believe are set up for man access, though for security reasons it’s probably best I don’t post which ones. I’ve no idea what they actually contain (the ones concerned happen to be on the only section of Vic Line which I’ve never had the opportunity to explore at track level!), but going by what exists elsewhere I’d suggest it’s probably something like a small metal spiral staircase.

The size of the head house will generally be for two reasons - firstly the tunnel fans are quite large, and secondly because the tower needs to be taken up to whatever is the prevailing roof level.

Thanks North End. Without meaning to breech security myself, I note on the TfL Property Asset Database Map linked above by Quex, the Somerleyton road shaft in Brixton is labelled as emergency escape, perhaps for safety reasons because it is at the end of the running lines, and potentially for T/Ops to escape from there if they find themselves 'trapped' in the siding in the event a train terminates there? I don't believe there is an equivalent set up on the opposite end of the line at Walthamstow.

On the topic of that Property Asset Database Map, unless there is a layer switched off that I am not aware of, it's a shame that many of the other lines aren't as detailed as the Victoria line is. For example the Victoria line sidings are displayed, complete with the emergency escape cross passages at the end of the sidings to connect with the mainline running tunnels. Whereas the Piccadilly line, for instance, lacks any such detail.

--

For those interested, there's a useful diagram in the following ICE article entitled 'Squeezing the heat out of London's Tube', which shows where the shafts are and how they work: www.icevirtuallibrary.com/doi/pdf/10.1680/cien.2010.163.3.114?download=true

[North End]

Apr 9, 2021 11:06:24 GMT Alight said:

Thanks all for your informative responses and also the continuation of some of the interesting discussion about the Drayton Park - Finsbury Park tunnels - one thing's for sure, I really hear/feel the gust of air whenever I travel past this stretch on the Victoria line, as they serve as natural ventilation... arguably more effective than some of the purpose-built intermediate fan shafts, many of which you don't hear/feel when the train goes past them (maybe because the fans are switched off these days?) I know there were some complaints about the Pulross Road shaft when the fans were upgraded back in '09: brixtonblog.com/2019/12/resident-protest-sees-giant-brixton-fan-switched-off/?cn-reloaded=1

Apr 7, 2021 22:30:48 GMT North End said:

In general the answer is very much no.

However, there is of course the Netherton Road shaft which is setup as an escape location, and has always been so since day one. There’s a couple of other fan shafts on the Vic Line which I believe are set up for man access, though for security reasons it’s probably best I don’t post which ones. I’ve no idea what they actually contain (the ones concerned happen to be on the only section of Vic Line which I’ve never had the opportunity to explore at track level!), but going by what exists elsewhere I’d suggest it’s probably something like a small metal spiral staircase.

The size of the head house will generally be for two reasons - firstly the tunnel fans are quite large, and secondly because the tower needs to be taken up to whatever is the prevailing roof level.

Thanks North End. Without meaning to breech security myself, I note on the TfL Property Asset Database Map linked above by Quex, the Somerleyton road shaft in Brixton is labelled as emergency escape, perhaps for safety reasons because it is at the end of the running lines, and potentially for T/Ops to escape from there if they find themselves 'trapped' in the siding in the event a train terminates there? I don't believe there is an equivalent set up on the opposite end of the line at Walthamstow.

On the topic of that Property Asset Database Map, unless there is a layer switched off that I am not aware of, it's a shame that many of the other lines aren't as detailed as the Victoria line is. For example the Victoria line sidings are displayed, complete with the emergency escape cross passages at the end of the sidings to connect with the mainline running tunnels. Whereas the Piccadilly line, for instance, lacks any such detail.

--

For those interested, there's a useful diagram in the following ICE article entitled 'Squeezing the heat out of London's Tube', which shows where the shafts are and how they work: www.icevirtuallibrary.com/doi/pdf/10.1680/cien.2010.163.3.114?download=true

Someone with local knowledge would have to confirm, however I don’t believe there’s access at Somerleyton Road. The cross passage from one siding to the other would satisfy any emergency egress requirement. My guess is the shaft probably has a rudimentary ladder.

I did walk down the sidings when exploring that part of the Vic Line, however there were trains stabled in there so we didn’t go right to the end.

I’ve certainly seen no mention anywhere of any facility for staff to be able to leave there - but having said that there’s plenty of places I am familiar with where it’s possible to do that but which aren’t officially listed as such. Even some of the outwardly obvious ones like disused stations aren’t that well documented - the Met Line ones between Baker Street and Finchley Road are very much on the radar, but somewhere like Bull & Bush isn’t. The main use for these features is for contractors and the like.

[Alight]

Just to add to your examples there, there is also the small tunnel at the very end of the Down Street siding, which links through to the Hyde Park Corner crossover. That's not to mention Down Street station itself, though the main beneficiaries of its signage and designated escape route are more likely to be the contractors working down there on the IMR as opposed a T/Op using the siding or indeed having to evacuate a train (I don't think there have been any recorded evacuations down there).

I suspect in the case of Somerleyton Road on the Victoria line, the T/Ops are more likely to leave the train by performing a track walk back to Brixton once the traction current is switched off. Certainly this is what happens on the Bakerloo line at E&C.

[North End]

Apr 10, 2021 11:09:10 GMT Alight said:

Just to add to your examples there, there is also the small tunnel at the very end of the Down Street siding, which links through to the Hyde Park Corner crossover. That's not to mention Down Street station itself, though the main beneficiaries of its signage and designated escape route are more likely to be the contractors working down there on the IMR as opposed a T/Op using the siding or indeed having to evacuate a train (I don't think there have been any recorded evacuations down there).

I suspect in the case of Somerleyton Road on the Victoria line, the T/Ops are more likely to leave the train by performing a track walk back to Brixton once the traction current is switched off. Certainly this is what happens on the Bakerloo line at E&C.

Hyde Park Corner is listed as a means of accessing Down Street siding (though one wonders if this ever happens in practice - surely easier to be taken by train and dropped off at the points?). For Brixton the official means of entry is walking from the platforms, there’s no mention anywhere of anything else.

[nig]

Apr 10, 2021 11:18:17 GMT North End said:

Apr 10, 2021 11:09:10 GMT Alight said:

Just to add to your examples there, there is also the small tunnel at the very end of the Down Street siding, which links through to the Hyde Park Corner crossover. That's not to mention Down Street station itself, though the main beneficiaries of its signage and designated escape route are more likely to be the contractors working down there on the IMR as opposed a T/Op using the siding or indeed having to evacuate a train (I don't think there have been any recorded evacuations down there).

I suspect in the case of Somerleyton Road on the Victoria line, the T/Ops are more likely to leave the train by performing a track walk back to Brixton once the traction current is switched off. Certainly this is what happens on the Bakerloo line at E&C.

Hyde Park Corner is listed as a means of accessing Down Street siding (though one wonders if this ever happens in practice - surely easier to be taken by train and dropped off at the points?). For Brixton the official means of entry is walking from the platforms, there’s no mention anywhere of anything else.

It does happen in practice have done that walk myself a few years ago it only normally happens if there is a defective train is in there as current has to get turned off before walking in there

[North End]

Apr 10, 2021 16:43:29 GMT nig said:

Apr 10, 2021 11:18:17 GMT North End said:

Hyde Park Corner is listed as a means of accessing Down Street siding (though one wonders if this ever happens in practice - surely easier to be taken by train and dropped off at the points?). For Brixton the official means of entry is walking from the platforms, there’s no mention anywhere of anything else.

It does happen in practice have done that walk myself a few years ago it only normally happens if there is a defective train is in there as current has to get turned off before walking in there

Fair enough. I was wondering as at Kennington the official access route used to be much further than the easy way, perhaps reflecting past operating practices. Certainly I never knew the official way happen, and by the time TBTC came in the easy way had been made official.

[programmes1]

I'm sure online there is a list of shafts and what they are for.

[superteacher]

Apr 11, 2021 9:07:15 GMT programmes1 said:

I'm sure online there is a list of shafts and what they are for.

Not doubting you, but would there be a danger of misuse if that information was in the public domain?

[programmes1]

Apr 12, 2021 20:25:52 GMT superteacher said:

Apr 11, 2021 9:07:15 GMT programmes1 said:

I'm sure online there is a list of shafts and what they are for.

Not doubting you, but would there be a danger of misuse if that information was in the public domain?

I'm sure there are people who would misuse the information but it is in the public domain one of the documents is a London Fire Brigade document. Some organisations put things online which contain a bit too much information.