SSR resignalling

[Dstock7080]

I see there is a 4-day closure of the Met between Harrow and Amersham between 19-22 Feb. Just wondering what work specifically is planned? Will any new signalling be going live? Thanks

SMA13 system test, Thursday-Sunday.

Next planned commissioning is District SMA10/12 in June

 

[JustPassingBy]

SMA13 system test, Thursday-Sunday.

Next planned commissioning is District SMA10/12 in June

Thank you.

 

[MatthewRead]

SMA13 system test, Thursday-Sunday.

Next planned commissioning is District SMA10/12 in June

Just out of interest on the 13/14th June is says first there will be no District line service at all until 10:00 then no service west of Embankment until 14:30 and after that no service to Wimbledon and it says between Barons Court and Stamford Brook now surely that can't be right because it isn't possible to reverse at either station and Barons Court will be partially closed due to vital repairs so how will services work?

 

[Dstock7080]

Just out of interest on the 13/14th June is says first there will be no District line service at all until 10:00 then no service west of Embankment until 14:30 and after that no service to Wimbledon and it says between Barons Court and Stamford Brook now surely that can't be right because it isn't possible to reverse at either station and Barons Court will be partially closed due to vital repairs so how will services work?

Trains will run empty in the newly commissioned Barons Court-Stamford Brook. Barons Court station should be open for this date.
During the eastbound closure District trains will have to stop to transition from manual to ATO operation.

 

[bluegoblin7]

Worth highlighting for the GB audience that the conventional signalling in the area under discussion has fully braked overlaps. In other words the consequences of a signal passed at danger are massively reduced compared with National Rail overlaps.

Also worth saying that fully braked overlaps are (generally) within the core principles of LUL conventional signalling. The existing 4-aspect kit on the Met has these too. It’s unusual for GB as a whole, but not for LUL.

 

[bramling]

So one has to wonder, since this is yet another "not moving block but small fixed blocks" signalling system, what was the advantage over DTG-R again? (Other than project politics).

Allegedly, cost, and perhaps also a small advantage that Seltrac systems do not require track circuits. It also probably simplified the interfaces at Neasden/Wembley.

Though given how long the SSL resignalling has progressed since the Westinghouse contract was dropped, any cost savings must surely have been obliterated many times over, as well as the issue that TFL has now backed themselves into a corner where they only have one realistic supplier for signalling systems which is not great from a cost point of view, and may well be a reason why Piccadilly resignalling keeps going into the “kick the can down the road” file.

For the avoidance of doubt, I agree TFL should have just stuck with DTG-R.

 

[Nym]

From my knowledge of the "CBTC" system, there is not advantage to integrating at Neasden, and it would have been easier with DTG-R.

For the avoidance of doubt, on a mixed traffic system of any kind, I am a firm believer that train detection should be an infrastructure issue so that unfitted or alien movements can actually happen.

 

[Silent]

From my knowledge of the "CBTC" system, there is not advantage to integrating at Neasden, and it would have been easier with DTG-R.

For the avoidance of doubt, on a mixed traffic system of any kind, I am a firm believer that train detection should be an infrastructure issue so that unfitted or alien movements can actually happen.

Why is that? I also notice the met line is slow Wembley Park to Neasden and then speeds up.

 

[D7666]

So one has to wonder, since this is yet another "not moving block but small fixed blocks" signalling system, what was the advantage over DTG-R again? (Other than project politics).

For context to the younger ones among us, DTG-R is what is used on the Victoria Line and is what was supposed to be used on the Sub Surface Railway until someone decided it was a bad idea and wanted to re-let the contract. Twice.

(Is also fully able to integrate with basically any interlocking system, so would have been able to have lights on sticks simply enough (as well as AWS, TPS, Trainstops, etc.) as well as block markers for DTG-R protected equipment.

AIUI CBTC (of any flavour, be it Thales/Hitachi Seltrac, or Eliz line type Siemens Trainguard, and so on) are more readily intregrated with ETCS while DTG-R was more difficult (or even impractical?). Long term - that is very long term - LU CTBC will have to interface with NR ETCS at some locations. More of a strategic long term plot to not get lumbered with a system that was more difficult/costly to interface.

If one considers the difficulties there were with getting all the different kits for different section to work on 345s, you'd want to head similar issues off. Down at the level of track to train bits and bytes, CBTC and ETCS are not a lot different, while underlying movement authority signalling principles are the same - it is the hardware and applications software higher up the layers and method of track to train communication that differ.

Further, Vic line (and Metronet inspired 4LM scheme) DTG-R utilises track circuits for train detection and protection; the other systems do not. For intense headway metro, you need a lot of close spaced short track circuits. The Victoria line is a simple self contained shuttle - DTG-R works there on what is a simple railway. But that Vic line upgrade was specified eon ago - DTG using track circuits is obsolete techonology, no-one would do it now. And. Track circuits are maintenance intensive and significant points of failure. So why would you replace legacy track circuits on the the surface lines with a system dependant on a significantly larger amount of track circuits.

 

[Nym]

AIUI CBTC (of any flavour, be it Thales/Hitachi Seltrac, or Eliz line type Siemens Trainguard, and so on) are more readily intregrated with ETCS while DTG-R was more difficult (or even impractical?). Long term - that is very long term - LU CTBC will have to interface with NR ETCS at some locations. More of a strategic long term plot to not get lumbered with a system that was more difficult/costly to interface.

If one considers the difficulties there were with getting all the different kits for different section to work on 345s, you'd want to head similar issues off. Down at the level of track to train bits and bytes, CBTC and ETCS are not a lot different, while underlying movement authority signalling principles are the same - it is the hardware and applications software higher up the layers and method of track to train communication that differ.

Further, Vic line (and Metronet inspired 4LM scheme) DTG-R utilises track circuits for train detection and protection; the other systems do not. For intense headway metro, you need a lot of close spaced short track circuits. The Victoria line is a simple self contained shuttle - DTG-R works there on what is a simple railway. But that Vic line upgrade was specified eon ago - DTG using track circuits is obsolete techonology, no-one would do it now. And. Track circuits are maintenance intensive and significant points of failure. So why would you replace legacy track circuits on the the surface lines with a system dependant on a significantly larger amount of track circuits.

Except some small problems.

The met line is a mixed traffic railway.
Standard interlocking will integrate quite nicely with ETCS/ERTMS without issue.
The track circuits had already mostly been replaced to immunise for S Stock's arrival and cut into the old interlocking. So that "cost" had already been done.

 

[D7666]

Except some small problems.

The met line is a mixed traffic railway.
Standard interlocking will integrate quite nicely with ETCS/ERTMS without issue.
The track circuits had already mostly been replaced to immunise for S Stock's arrival and cut into the old interlocking. So that "cost" had already been done.

Mixed traffic ? So what ? What problem is that to Seltrac that is better fixed by DTG ?

What on earth do you mean by "standard interlocking ? What standard ?

My point is about track circuit maintainance. Whether or not existing tracks were immunised for S stock is not the point - what is is that track circuits would have to have been retained under DTG, and a lot more of them, whereas Seltrac eliminates them.

 

[Snow1964]

The Metropolitan line will be closed Thursday 19th to Sunday 22nd Feb (4 days) from Harrow on the Hill to Amersham.

Chiltern line trains also unable to run due to the resignalling works.

In a piece of spectacular (lack of) coordination, apparently roadworks have been sanctioned in Chorleywood area on same dates on the proposed rail replacement bus routes

 

[AdamLukePaul]

The Metropolitan line will be closed Thursday 19th to Sunday 22nd Feb (4 days) from Harrow on the Hill to Amersham.

Chiltern line trains also unable to run due to the resignalling works.

In a piece of spectacular (lack of) coordination, apparently roadworks have been sanctioned in Chorleywood area on same dates on the proposed rail replacement bus routes

The works in and around Chorleywood have been long planned, and have been ongoing since about October 2025, I think from memory due to finish end of March.

 

[CarrotPie]

Trains will run empty in the newly commissioned Barons Court-Stamford Brook.

What's stopping them running with passengers?

 

[bluegoblin7]

The signalling being on test and not commissioned for public use

 

[CarrotPie]

The signalling being on test and not commissioned for public use

Oh. So they're testing and commissioning that section on that weekend, right?

 

[bluegoblin7]

Yes.

 

[Dstock7080]

Seems that Farringdon City sidings have been kicked into the very long grass, with the forthcoming (Feb 28-16 March) removal of 21, 22, 23, 24 points at Farringdon and disconnection of power supplies to the two sidings.

project delayed.

 

[SeaSquid]

Are the closures from today until Sunday related to resignalling works?

 

[Dstock7080]

Are the closures from today until Sunday related to resignalling works?

posts #511, #522

 

[A60stock]

Are trains being run regularly on the closed section on test? I've not heard a single one go by (I live close to the closed section)

 

[bluegoblin7]

Trains will be running regularly Friday and Saturday albeit perhaps not frequently, as is now relatively established for the ‘initial’ test weekends.

Today was primarily for preparing the possession area, including bagging and unbagging old and new signals, pegging and unpegging old and new trainstops, and setting up protection for the test area, amongst other things.

 

[rebmcr]

How are the works proceeding?

 

[Dstock7080]

Unfortunately a derailment at Neasden south junction has added to complications

 

[xtmw]

Believe it ran through a set of points (S8, not 96)

 

[Route115?]

A lot of the indicators on sub-surface stations are displaying 'Check Front of Train'. Why is this? Tubestatus seems to be showng it for departures more than 15 minutes away. I was at Baker St yesterday and the Next City Train was shown as a departure to Edgware Rd from Platform 5 (eastbound Circle / H&C). Absolutely correct but confusing for a visitor who would find a quicker train from Plat 6.

 

[SeaSquid]

Any news/progress after the last testing?

 

[Belperpete]

A lot of the indicators on sub-surface stations are displaying 'Check Front of Train'. Why is this?

I noticed at West Brompton today, trains coming from Wimbledon weren't appearing on the departure indicator until they actually arrived in the platform. So no indication of how long we had to wait for the next train, until we could see it!

 

[zwk500]

TfL Board Papers for the March 18 Meeting have 2 Milestone Dates for the Four lines Modernisation:

SMA 10 and SMA 12 Go-Live target 30th September, SMA 9 Go-Live target 30th November.

From Appendix 3: Investment Programme milestones, Page 143 of file, numbered P.139.

	Portfolio	Project Name	Milestone Description	Target
4	Four Lines Modernisation	Four Lines Modernisation	Service running on a new signalling system on the District line between Fulham Broadway and Putney Bridge and between Barons Court and Richmond/Ealing Broadway (Signal Migration Areas 10 and 12 'Go Live')	30/09/2026
11	Four Lines Modernisation	Four Lines Modernisation	Service running on a new signalling system on the Metropolitan line between Preston Road, West Harrow and Moor Park (Signal Migration Area 9 'Go Live')	30/11/2026

File link: https://board.tfl.gov.uk/documents/g951/Public reports pack Wednesday 18-Mar-2026 10.00 Board.pdf?T=10
Meeting Page link: https://board.tfl.gov.uk/ieListDocuments.aspx?CId=138&MId=951&Ver=4

The October 2025 Programmes and Investment Committee lists SMA 10 as being Barns court to Stamford Brook only, and SMA 12 as Fulham Broadway to East Putney.

8.1.6 We are now focusing on preparations for the introduction of the new signalling system in SMA9 (the Harrow area) and SMA10/SMA12 (Barons Court to Stamford Brook and Fulham Broadway to East Putney).

https://board.tfl.gov.uk/documents/g938/Public%20reports%20pack%20Wednesday%2008-Oct-2025%2010.00%20Programmes%20and%20Investment%20Committee.pdf?T=10

Choose agenda document pack - Programmes and Investment Committee 8 October 2025 - Modern Council

board.tfl.gov.uk

I am guessing that the March Board meeting paper has older descriptions from before the scaling back of SMA 10, but has SMA 12 been further adjusted to keep clear of the interface at East Putney?

 

[rorbla]

Does anyone know if the Aldgate junction renewal/remodelling is still expected to go ahead later this year?

With ATO having been recently implemented as part of 4LM, is it likely to minimise the amount of waiting for H&C and District Line services entering the ‘Circle’ from the east?

Also, it feels like line speeds on the District through East London have been pretty slow recently - trains absolutely aren’t accelerating as much or reaching as high speeds as previously. Is this likely to be improved any time soon?