SSR resignalling

[Chrius56000]

A couple of questions!

On recent Northern and Circle Line Tube journeys I noticed there are still quite a number of the old filament–bulb two aspect colour–light signals still in place, altho' crossed out or bagged over – are these being retained for emergency use, or will LU remove them when full TBTC/ATO is in operation?

It might be a silly question to ask, but surely an emergency conventional colour–light backup system that's switched in automatically after a given period of failure, would save long periods of cancellations (12h in the case of Jubilee Line ATO failures!) – has LU given any thought to this?

I am given to understand that Moscow Metro drivers can request an emergency stand–by conventional fixed block system to be switched on which retains enough colour–lights along the lines to allow a reduced emergency service to operate!

Chris Williams

 

[bramling]

A couple of questions!

On recent Northern and Circle Line Tube journeys I noticed there are still quite a number of the old filament–bulb two aspect colour–light signals still in place, altho' crossed out or bagged over – are these being retained for emergency use, or will LU remove them when full TBTC/ATO is in operation?

It might be a silly question to ask, but surely an emergency conventional colour–light backup system that's switched in automatically after a given period of failure, would save long periods of cancellations (12h in the case of Jubilee Line ATO failures!) – has LU given any thought to this?

I am given to understand that Moscow Metro drivers can request an emergency stand–by conventional fixed block system to be switched on which retains enough colour–lights along the lines to allow a reduced emergency service to operate!

Chris Williams

Any signals (as well as all the associated equipment such as cables, relays etc) are there because there aren’t the resources and/or funding to do it. Indeed it’s rather remiss that the relevant contracts didn’t include removal of the old system. I believe the Victoria Line contract did, hence why on there little if anything remains to show the old signalling ever existed.

As regards having a fallback system, the cost of doing it would be very high. To have a “conventional” system in place there would have to be all the usual systems such as train detection and control systems, as well as the signals themselves. With something like Seltrac there are axle counter block sections, so it would theoretically be possible to rig something up, albeit only delivering basic functionality as the sections wouldn’t be ideally placed for an intensive service. But on top of that you also need to train staff, and of course maintain such a system. So it isn’t going to be cost effective.

The nearest we get is on the Central and Victoria lines where the ATC system retains signals. On the Central Line there was an idea that they might be used to accommodate “unfitted” (with ATC) trains. Indeed this was used during the overnight Central Centenarian railtour in 2000. It does also allow some level of slow-speed running during some failures. The CBTC and TBTC systems don’t really lend themselves to this.

 

[bluegoblin7]

A couple of questions!

On recent Northern and Circle Line Tube journeys I noticed there are still quite a number of the old filament–bulb two aspect colour–light signals still in place, altho' crossed out or bagged over – are these being retained for emergency use, or will LU remove them when full TBTC/ATO is in operation?

In theory they will be removed, but as the Northern and Jubilee line demonstrates that’s anyone’s guess. The signals are fully decommissioned and many of the locations that controlled them no longer exist.

The reality is that the removals budget is the first to be cut - see also the CBTC parts of the SSR which were supposed to be learning from past challenges with JNUP.

It might be a silly question to ask, but surely an emergency conventional colour–light backup system that's switched in automatically after a given period of failure, would save long periods of cancellations (12h in the case of Jubilee Line ATO failures!) – has LU given any thought to this?

It’s not a silly question, but the short answer is no. What failures of ATO equipment have occurred that might warrant such a back up system? Very few. Those that have have been largely due to a signal point of failure - the physical control room. A remote back up would allow a service to continue running if needed. The reality is that the ATO systems have multiple layers of redundancy and, in the vast majority of cases, “signal failures” are in fact other assets.

Additionally, who pays for the back up system to be designed, installed, tested and commissioned? How is it maintained? On LUL’s legacy track circuited lines, trains have to run over every piece of track approximately every 48 hours to protect the integrity of the signalling system. How do you ensure this happens with a back up, given it won’t be in active use nor being monitored?

Finally - staff competency. How do you ensure control and train staff remain competent and familiar with the back up system?

The reality is that the ATO systems are no less reliable than the legacy signalling before it, with robust procedures in place to assist on the rare occasions that things do go wrong.

 

[Bald Rick]

It might be a silly question to ask, but surely an emergency conventional colour–light backup system that's switched in automatically after a given period of failure, would save long periods of cancellations (12h in the case of Jubilee Line ATO failures!) – has LU given any thought to this?

Worth bearing in mind that a failure of the signallign system may well be a failure that would affect the back up system too. Or that the back up system will fail more than the main system.

 

[AlbertBeale]

Additionally, who pays for the back up system to be designed, installed, tested and commissioned? How is it maintained? On LUL’s legacy track circuited lines, trains have to run over every piece of track approximately every 48 hours to protect the integrity of the signalling system. How do you ensure this happens with a back up, given it won’t be in active use nor being monitored?

Fascinating - please explain!

 

[100andthirty]

The moves "approximately every 48 hours" are known as "rusty rail moves". Does that explain it?

 

[JustPassingBy]

The moves "approximately every 48 hours" are known as "rusty rail moves". Does that explain it?

I.e. so if not done a layer of rust builds up breaking electrical conductivity, which means track circuits don't report train locations correctly.

 

[100andthirty]

Wandering off topic, it's unlikely that track circuits would be used for this mythical back up signalling system. These days, axle counters are more dependable.

 

[D7666]

In theory they will be removed, but as the Northern and Jubilee line demonstrates that’s anyone’s guess. The signals are fully decommissioned and many of the locations that controlled them no longer exist.

The reality is that the removals budget is the first to be cut - see also the CBTC parts of the SSR which were supposed to be learning from past challenges with JNUP.

All the 4LM CBTC engineering briefings I have been too, admittedly none of late, explicitly stated there is no specific asset removal, meaning any and all assets. Repeat that, this was explicit information in briefings.

I can't say if this has changed since, but given there is even less money for anything now than there was when we were told that, IMHO I can't see things have changed.

For example air taken off interlocking frames, fuses taken out of colour light signals (and bagging over) and track circuits, and (I think ?) train stops removed (or locked down ?) - but nothing more - except maybe odd locations where some obstruction has to be removed. Unless that is anyone does know more.

Wandering off topic, it's unlikely that track circuits would be used for this mythical back up signalling system. These days, axle counters are more dependable.

Yes, but we already have axle counters in our CBTC ATO system anyway, as part of the main system. It would be somewhat complex to make these work as both the main system and a back up system, and even if so, the whole is still a single point of failure, so would achieve nothing.

As it happens I am involved with certain engineering aspects of back up control room(s) facilities - I am not going to divulge any more than that - but will say that every point posted by my Learned Colleague bluegoblin7 is valid, and I am not even a service operator with the detailed knowledge of what they might need.

Additional comment: NR does not have back up locations for it's ROCs or IECCs or major power boxes and so on. The same reasons apply: how do you test, commission, maintain, and retain (or even obtain) competency, and so on.

 

[ijmad]

Is the idea to remove the old equipment gradually over the next few decades as the permanent way is maintained / gradually renewed?

 

[D7666]

Is the idea to remove the old equipment gradually over the next few decades as the permanent way is maintained / gradually renewed?

Does it matter ?

 

[ijmad]

Does it matter ?

I don't know! Without maintenance might the old signals or wiring become corroded? Or maybe they'll make nice little houses for tube mice?

 

[zwk500]

I don't know! Without maintenance might the old signals or wiring become corroded? Or maybe they'll make nice little houses for tube mice?

Things getting corroded doesn't really matter if they're not connected to anything, and mice are going to find houses wherever so it's neither here nor there.

As always, it will depend if the cost of taking the equipment back, and then disposing of it, is worth it in scrap or spares. Given the intention is to move to no signals, spares would have limited value especially as more areas migrate, and the scrap value of a signal that's sat in a tube tunnel for however long probably isn't going to be huge either.

Plenty of old signals left hanging around on the mainline railway - generally they're only worth recovering if they're getting in the way of current operations.

 

[Nym]

Quite asside from the mechanical issues of having all these old assets around.

1) It looks really untidy, hardly a world class example.
2) It gets in the way of new assets, given the asset records for these redundant assets will be lost / misplaced. A future project will come along and need space in cable trays, only to find all these old signalling cables that we don't know if they're live or not, then to add to the issue all the other cables strung in with it making the eventual removal a much more complex process with many more stakeholders than if it had just been mopped up at the end of the job like it was on VLU.

 

[bramling]

I don't know! Without maintenance might the old signals or wiring become corroded? Or maybe they'll make nice little houses for tube mice?

There has certainly been a problem with signals suffering from corrosion, especially with no maintenance, and the bags trapping water rather than allowing it to evaporate. At least one complete signal head on the Northern Line managed to completely fall off its post, which given how heavy they are is pretty undesirable from a safety point of view. Worse would be if a complete signal and post managed to fall over onto the track, something which ISTR has happened on Network Rail.

Generally these sorts of redundant assets should be being removed sooner rather than later. It’s really poor that the Jubilee and Northern lines still have plenty of old signals and associated assets in place some 10+ years on.

 

[LowLevel]

Things getting corroded doesn't really matter if they're not connected to anything, and mice are going to find houses wherever so it's neither here nor there.

As always, it will depend if the cost of taking the equipment back, and then disposing of it, is worth it in scrap or spares. Given the intention is to move to no signals, spares would have limited value especially as more areas migrate, and the scrap value of a signal that's sat in a tube tunnel for however long probably isn't going to be huge either.

Plenty of old signals left hanging around on the mainline railway - generally they're only worth recovering if they're getting in the way of current operations.

To be fair rotten old signal posts and the like falling over has become a bit of a focus point on NR in recent years with plenty of works undertake to remove life expired structures whether they're in work or not - there have been a few occasions where they've fallen over and become a hazard to traffic which is obviously far from desirable.

I know of at least one almost permanently switched out signalbox that has nevertheless had replacement semaphore signals installed due to corrosion.

 

[A60stock]

Interesting that all rails needs to be run over every 48 hours.

Here's one I always wondered how often its used and why trains run over it so slowly:

The crossover on the Metropolitan line just South of Finchley Road - Never seen this used or any train terminate at FR. Are there any scheduled moves over it?

 

[D7666]

Interesting that all rails needs to be run over every 48 hours.

I will have to go back and check in WTT, and I may be wrong, but my memory of these things is a tube tunnel section is only once per week. At least rust from precipitation is less in tunnels, or ought to be.

When I was on Central Line (engineering not operating) there were once per week 'rusty rail' movements into the Marble Arch, Holborn (now gone), and Liverpool Street (once for each road here) reversing sidings that had no other booked moves.

It was all done by one train on a Sunday morning, I forget the precise details but it was something like a westbound in service tipped out at Marble Arch, then empty, reverse, remain empty, Liverpool Street one of the sidings, reverse, Holborn, reverse, Liverpool Street other siding, reverse, then enter service Liverpool Street and continue.

ALL of those sidings always used by operators during incidents - they were not unused - but those events are unpredictable, the rusty rail moves ensuring they really would be available when needed.

 

[bramling]

I will have to go back and check in WTT, and I may be wrong, but my memory of these things is a tube tunnel section is only once per week. At least rust from precipitation is less in tunnels, or ought to be.

When I was on Central Line (engineering not operating) there were once per week 'rusty rail' movements into the Marble Arch, Holborn (now gone), and Liverpool Street (once for each road here) reversing sidings that had no other booked moves.

It was all done by one train on a Sunday morning, I forget the precise details but it was something like a westbound in service tipped out at Marble Arch, then empty, reverse, remain empty, Liverpool Street one of the sidings, reverse, Holborn, reverse, Liverpool Street other siding, reverse, then enter service Liverpool Street and continue.

ALL of those sidings always used by operators during incidents - they were not unused - but those events are unpredictable, the rusty rail moves ensuring they really would be available when needed.

There are certainly pieces of track on LU that see no timetabled movements at all. I might be misremembering, however I think there it is decided at a joint ops / engineering level as to which sections need rusty rail moves. I assume it’s those deemed as being more critical for use in emergency.

If we take the Northern Line there’s nothing booked to reverse at Moorgate, Charing Cross or Mornington Crescent for example. Likewise rusty rail moves can be and are often cancelled - sometimes even for no other reason that nobody can be bothered to run them!

 

[100andthirty]

Tube tunnel track is usually very dry. I remember walking the Victoria line between Green Park and Oxford Circus during engineering hours many years ago. Rail that had been replaced some weeks before was still in the 4 foot and whilst dirsty, was still rust free.

 

[Central]

Xover south of Finchley Rd is Swiss Cottage disused station is often used during disruption also been used if line south of Finchley Rd is closed for engineering work.Don’t know if Xover north end of Finchley Rd is still there since segregation of Jubilee and Met Lines.

 

[Dstock7080]

Don’t know if Xover north end of Finchley Rd is still there since segregation of Jubilee and Met Lines.

Removed

 

[A60stock]

In all my years I cannot remember the last time I have seen a train terminate at Finchley Road, nor when there are planned closures, during which it's either (going southbound) the service closed south from one of Harrow, Wembley, or Baker Street.

 

[DavyCrocket]

The crossover south of Finchley Road (at Swiss Cottage disused) is used should there be a problem unresolvable south of and the need to send any delayed southbound trains back north, as well as if a train has failed to be in the automatic system, such as only restricted manual only and needs to be removed to a tripcock area.

I have a recollection of a signal that was corroded and fell, at the east end of the District but can’t remember if it was LU on to NR or vice versa

 

[D7666]

In all my years I cannot remember the last time I have seen a train terminate at Finchley Road, nor when there are planned closures, during which it's either (going southbound) the service closed south from one of Harrow, Wembley, or Baker Street.

This one reversed SB to NB there, which is the same as one train terminating then starting as another, twice, as each portion did it :

Six Bells Junction

I know that is not you meant, it is just an interesting anecdote about Finchley Road.................and

Me being me (and one of the SEG organisers) arrived on 1032 and departed on 1002.

There is a full suite of photos somewhere on the web with the loony things that/those train/portions did on LT metals.

 

[philthetube]

There is/was a rusty rail move south of Finchley rd. on a Sunday night, the last Baker St. service is followed by a train which reverses there and returns to Neasden. It is also commonly used by sleets and engineering trains.

 

[Central]

In 1975, when they were doing remedial work between Finchley Road and Baker Street, the Met service terminated at Finchley Road and ran empty to Swiss Cottage to reverse.

 

[JustPassingBy]

Wondering what the dates are for the switchovers of the remaining areas? Have they been set?

 

[Dstock7080]

no commissioning dates yet
SMA 8 Finchley Road-Preston Road testing 13-14 April, then other dates in June.

 

[D7666]

Wondering what the dates are for the switchovers of the remaining areas? Have they been set?

An updated schedule with commissioning date was issued internally the week before xmas but is not external info and I am afraid I can not post it.

That does not answer your first question I know - occasionally there are these dates and things that some of us are actually working to and on that we can not break confidentiality rules on. The second questions answer is yes commissioning dates are set.