SSR Resignalling

Yes, as CBTC migration can’t be performed on the move.

This was something and nothing.

Based on what I've read a 20 minute delay was incurred after the CBTC system caused a Circle line train operating in ATO to emergency brake part way into the platform. Once the train was fully berthed using appropriate procedures, the CBTC system was able to be successfully reset and the train carried on in ATO.

It has to be said that on the whole the CBTC system in the SMA3 area (Euston Square/Monument to Stepney Green) is performing extremely well. East end District line drivers are getting their first taste of ATO using the CBTC system and they have embraced it despite support from Instructor Operators being limited due to Covid.

There are certainly positive vibes about the District line at the moment with drivers looking forward to SMA4 (Monument to Sloane Square).

Some speed limit comparisons for SMA 3 on the north side of the Circle. Note that the reference points are approximations which help to match up former speed limits with the somewhat more frenetic nature of target speeds with CBTC.

The average speed under legacy signalling on the eastbound was 34 mph compared with 33 mph under CBTC. 
SMA 3 - Euston Square to Liverpool Street Eastbound (1) by goldenarrw, on Flickr

The average speed under legacy signalling on the westbound was 31 mph compared with 34 mph under CBTC. 
SMA 3 - Liverpool Street to Euston Square Westbound (1) by goldenarrw, on Flickr

roughly what date is SMA8 planned to go live and what date is SMA9 planned to go live? Basically wondering how long fast trains will be held at preston for?

Interesting speed graphs. Generally it looks convincing that westbound is faster overall

I believe the boundaries are usually away from controlled areas, as recent SMA 3 Stepney Green, Monument and Euston Square are all in automatic signal areas.
Barons Court is the only one planned in a controlled area.

The idea is for CBTC to replace conventional signalling on the ground and the control room/signal cabin. Wembley Park control, currently Baker Street extends beyond the platforms to the southbound home signals and approaches into Neasden depot. Northbound control ends with the station starters.

SMA 3 saw the end, not just of Whitechapel signal cabin but also the conventional individual control desks for Tower Hill, King’s Cross, Farringdon, Moorgate, Liverpool Street, Aldgate and Aldgate East all moved to Hammersmith.

Good observation, let's see how this will synchronise with SMA4.

Apologies if this has been covered elsewhere in this thread - maybe my search criteria were off - but I was wondering if it would have made matters easier for the section of the Piccadilly line between Ealing Common and Rayners Lane to be transferred to the District line. My thinking is that it would avoid complications of different stock running between Rayners Lane and Uxbridge and only require one signalling system rather than two, along with modifications to the '73 stock. No doubt it's too late for such an idea to be implemented, but I wonder if it would have been beneficial or was even considered during planning?

Thanks, that's interesting.

Money would be key answer in explaining why standardisation has been a long time coming on the Underground. Historically, London Transport grappled with the same issues TFL finds itself in, being unable to commit to long-term upgrade programmes due to the financial/political limitations that come with running a statutory corporation in this country. Had these obstacles been overcome, we could have had a network entirely signalled through the kind of pioneering ATO systems that made the Victoria line a success. Even when ATO was sidelined in favour of concentrating signalling control through the 70s and 80s, several projects stalled for the same reasons.

TFL only just about managed to cobble together enough to kickstart the fleet replacement of the Picadilly line and even then, re-signalling remains an aspiration. A fairly resolute aspiration with a strong business case, but an aspiration nonetheless. It would be in the best interests of 4LM for the Piccadilly to get the same Thales treatment, we await to see whether that will actually happen.

The TfL application for S stock exemption from the Rail Vehicle Accessibility Regulations (RVAR) was available on the DfT website. It mentioned that consideration was given to segregation of rolling stock types in a 2005 study of West London services but was considered poor value for money, and that that study could be made available to the Department if required. The study covered peak services to all western branches of the District and Piccadilly Lines, testing seven different route combinations with 33 different service patterns in all. At that time the PPP promised fully upgraded services on both lines by 2015, so this was considered the final chance for a revision of service plans before funds were fully committed. The study considered options for minimising line interworking and compromise height platforms in view of the RVAR requirements. Summary was in Underground News January 2014.

Very disappointing that the eastbound is actually slower than before - if it was not for the faster speed between Kings Cross and Farringdon the overall speed limit reduction would have been even more significant!

I am baffled as to why there should be any speed limit reductions anywhere - it almost implies that the previous speed limits were not safe, or is it that trains never ever reached the previous limits whilst under CBTC they might have done so - but this happening was felt to be 'undesirable'.

My understanding is that the entire section gets remapped to current standards, which does result in some variations to maximum speed, both up and down.

This isn’t unique to SSR, every line has had the same, even I believe the Central back in the 1990s.

One should not confuse this with Seltrac’s way of regulating the service, which is to calculate and impose a velocity ceiling should the system calculate that a train would otherwise arrive early at its next station. This was very commonly seen on the Northern in the early days, but less so once the upgrade timetables came in.

The Vic Line system works differently, originally is calculated a coasting point where the train would shut off and coast to the next station, which is a vastly superior way of doing things, more akin to what a real driver would do. However I have a feeling I read somewhere that the Vic has since had a software change and now does things slightly differently, which would tie in with a difference in train behaviour that I’ve noticed in the last couple of years. I’d certainly be interested if anyone can comment more on this.

In short, expect trains on the SSR to run a bit quicker once the proper timetables are in, though the real issue is simply that the Baker Street to Aldgate section handles a lot of trains, all coming from separate origins, so there’s always going to be some bunching. We shouldn’t judge until the system is in place across the board, though from experience on other lines I wouldn’t expect the system to be earth-shattering, especially during disruption.

In the meantime, if you want a fast run, you probably will need to be on a train which is running late, and of course which has a clear run. The Hammersmith signalling staff will need to beware of having an on-time train stuck in front of a late one, as in this situation the on time train gets a slow run and further holds up the late one. The way round this is for the signaller to modify the timings of the first train, but it relies on the situation being noticed and the signaller not busy dealing with something else.

Incidentally I believe the Northern is in the process of having some speed uplifts as part of the Battersea preparations. I haven’t been around recently, so can’t comment further on this at the present time. 60 mph in the open is a possibility, this has been in the cards for a while.

Individual car load data does exist on S stock but the ATC only transmits a 3 level loading for the whole train and as far as I know, no further system uses that off train as yet. There was work done on transmitting and using the more detailed data via a non-Signalling oriented channel, but shelved for the moment I think. Interesting to see if ridership revives enough to warrant this sort of thing.
Sorry if this is drifting more into the Covid thread.