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The Four Line Modernsiation Programme stretches all across the sub surface network, with the notable exclusion of the District line branches to Richmond, Ealing Broadway and Wimbledon.
Originally, these were all planned to reduce the upgrade, however were cancelled after COVID in order to reduce costs.
I see this as a very short sighted decision considering all the District line trains originate from one of these branches, and therefore the improved reliability that comes with the system is almost entirely irrelevant as failures can occur on the legacy sections and then block the entire line up.
No - at least not as part of the current 4LM programme. CBTC has been formally cancelled between south of Putney Bridge and west of Stamford Brook. This is primary due to the complexities of interfacing CBTC with the existing Network Rail interlockings on the Wimbledon and Richmond branches.
The Acton Town and Ealing Broadway area has also been descoped, in part to tie in with the above descopings but also due to the complexities of providing lineside signalling for Piccadilly line trains (the ‘interoperable area’) and the fact that PICU (Piccadilly Interim Control Upgrade) has significantly increased signalling reliability in that area over the last few years. It is now likely that this area will be resigned as part of any future Piccadilly line scheme. Whilst it will almost certainly be a flavour of CBTC, it won’t necessarily be the Thales/Hitachi Seltrac product and it is currently unfunded.
PICU essentially provided a new control system on top of the Piccadilly line’s existing mechanical interlockings, replacing legacy push button panels and programme machines controlled from Earl’s Court. The last part of Earl’s Court control room, which controls the Parsons Green area, is due to close late this year, drawing to an end that era of LU signalling. PICU currently controls all train movements on the Piccadilly line, as well as the District line between west of Barons Court (fringing to Hammersmith SCC and CBTC), west of Turnham Green (fringing to Richmond NR legacy signalling) and Ealing Broadway.
The Four Line Modernsiation Programme stretches all across the SSL network, with the notable exclusion of the District line branches to Richmond, Ealing Broadway and Wimbledon.
Originally, these were all planned to reduce the upgrade, however were cancelled after COVID in order to reduce costs.
I see this as a very short sighted decision considering all the District line trains originate from one of these branches, and therefore the improved reliability that comes with CBTC is almost entirely irrelevant as failures can occur on the legacy sections and then block the entire line up.
For the forseeable future - no. The money isn’t there, but the real issue is complexity.
I suspect the matter will be re-visited when the existing signalling on these sections becomes necessary for renewal. From a performance point of view the benefits are marginal at best, especially to Wimbledon and Richmond. It’s convenient that the existing signalling is comparatively modern, so it’s possible to take the “do nothing” option without much consequence.
The Wimbledon branch had a real mare on Saturday because of a Network Rail signal failure, I wonder what can be done to mitigate those issues in the future.
The Wimbledon branch had a real mare on Saturday because of a Network Rail signal failure, I wonder what can be done to mitigate those issues in the future.
"Signal failure" refers to a problem with a points-moving machine far more often than other sorts of problems. Those will happen no matter what flavour of system controls it, and no matter whose logo is on the signalling centre's front door.
"Signal failure" refers to a problem with a points-moving machine far more often than other sorts of problems. Those will happen no matter what flavour of system controls it, and no matter whose logo is on the signalling centre's front door.
It’s probably fair to say that the bottom end of the Wimbledon branch seems to see more than its fair share of infrastructure failures, though I’m not going to attempt to speculate as to why this might be.
In theory, a CBTC-type system should offer an improvement in reliability, die to a reduction in the number of moving parts and also the amount of cabling required. On top of that, being newer all the assets should be less prone to failure. For balance, CBTC does have failures of its own, and when they occur they tend to be massively disruptive. So its swings and roundabouts really.
In the first instance I’d be looking at why the Wimbledon branch seems to be so unreliable, and seeing what could be done to the existing assets to improve their performance. There shouldn’t be anything inherently unreliable there, so it’s a bit unclear why this seems to have been a perennial issue.
== Doublepost prevention - post automatically merged: ==
"Signal failure" refers to a problem with a points-moving machine far more often than other sorts of problems. Those will happen no matter what flavour of system controls it, and no matter whose logo is on the signalling centre's front door.
It’s probably fair to say that the bottom end of the Wimbledon branch seems to see more than its fair share of infrastructure failures, though I’m not going to attempt to speculate as to why this might be.
In theory, a CBTC-type system should offer an improvement in reliability, die to a reduction in the number of moving parts and also the amount of cabling required. On top of that, being newer all the assets should be less prone to failure. For balance, CBTC does have failures of its own, and when they occur they tend to be massively disruptive. So its swings and roundabouts really.
In the first instance I’d be looking at why the Wimbledon branch seems to be so unreliable, and seeing what could be done to the existing assets to improve their performance. There shouldn’t be anything inherently unreliable there, so it’s a bit unclear why this seems to have been a perennial issue.
I recall problems with this area during Wimbledon tennis tournament which rattled some cages - so perhaps this will spur reliability investigations & improvements along - on the other hand the impetus may have died away by now - needs someone in post long enough & to care ;-}
I don't think that the District Line on the Wimbledon branch has actually had a day without an issue since the strikes. It seems every day someone's fixing a signal fault at Southfields, East Putney or Parsons Green.
Presumably this means that 130-odd 7-car Stock units soldier on with tripcock equipment installed as a consequence, plus the need for retention of tripcock testers ?
Presumably this means that 130-odd 7-car Stock units soldier on with tripcock equipment installed as a consequence, plus the need for retention of tripcock testers ?
..and again! Full suspension this time Wimbledon <> Earl’s Court. Pretty sure it’s had minor or severe delays on the TfL live status page for the best part of a week now.
The Acton Town and Ealing Broadway area has also been descoped, in part to tie in with the above descopings but also due to the complexities of providing lineside signalling for Piccadilly line trains (the ‘interoperable area’) and the fact that PICU (Piccadilly Interim Control Upgrade) has significantly increased signalling reliability in that area over the last few years. It is now likely that this area will be resigned as part of any future Piccadilly line scheme. Whilst it will almost certainly be a flavour of CBTC, it won’t necessarily be the Thales/Hitachi Seltrac product and it is currently unfunded.
Slight tangent but strongly related - what's the current plan for the shared section of the Met/Picc between Rayners Lane and Uxbridge? I can't remember what the discussion on the main thread or other sites has said about SMA 14.
Note that much of the hardware for the 4LM signalling (with overlay of additional Axle counter sections, signals & trainstops) has already been installed Rayners Ln - Uxbridge.
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