SSR resignalling

Discussion in 'London Underground' started by Dstock7080, 22 Jun 2018.

  1. ijmad

    ijmad Established Member

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    Ah nice. I'm sure you'll let us know when they finalise the dates for commissioning and passenger service :D

    Having Praed Street and Baker Street junction under ATO seems like it could bring a lot of timing benefits, even if it will be a couple of years before we get speed/headway improvements.
     
  2. rebmcr

    rebmcr Established Member

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    Is it definitely ATO within the SMA sections? It's plausible that, until the legacy switchovers are eliminated, it's just an in-cab overlay.
     
  3. ijmad

    ijmad Established Member

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    I don't know, but I'm sure someone with more knowledge that me on the thread will.

    However, even if not ATO yet, it's a much more advanced signalling technology than coloured signals, having things like target speeds and moving blocks. Combined with central coordination of train movements, this would, I imagine, make coordination of conflicting moves across junctions a hell of a lot more straightforward.
     
  4. Mojo

    Mojo Administrator Staff Member Administrator

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    ATO was in use on the train I travelled on this afternoon.
     
  5. bramling

    bramling Established Member

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    Definitely ATO. It’s a fundamental part of the Thales system.

    The only time manual driving at line speed is done is when there’s people on or about the track, if examining the line or running at caution, or to preserve skills. Or if the driver feels like it, but the Thales system is so arsey and non-user-friendly that this takes serious dedication so only a very small number do it voluntarily.

    Having said that, I suspect they’re using the section to train drivers up, as each driver has to have a set number of trips with an instructor, some of these requiring to be in manual operation. So there might well be a fair bit of manual driving for that reason to begin with. On the Northern if my memory is right the requirement was six trips, at least two in auto and two in manual - not much, which is why many drivers are useless at manual driving under ATC!
     
  6. ijmad

    ijmad Established Member

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    What's the procedure like for moving from the new signalling to the old? Does the train have to come to a stop and flip some switches? Or is it done on the move?

    Also what's with the white exterior ATO lights on each carriage? Is that a safety thing to warn anyone trackside that the train is in automatic mode?

    Edit: answer on the white lights found in another place
     
    Last edited: 17 Mar 2019
  7. Dstock7080

    Dstock7080 Established Member

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    While there are migration point boundaries, the train must stop and the driver switches mode, physically leaving their seat to do so.
    At the station before a migration boundary the driver must check that the VOBC Vehicle On Board Controllers (x2) are communicating with the CBTC system. At the actual boundary station a colour light signal will display a red aspect, the driver will switch to ATO, wait 5 seconds and if the train and system accepts the authority to proceed, the signal aspect will change to blue. (During the 5 seconds the tripcock arm will be automatically physically lifted by the tripcock latch relay). Once the systems are talking the driver will receive “ATO start required” on the SID Signal Interface Display.

    (the CrossRail version of CBTC is supposed to work on the move, one of the many problems they face).

    From CBTC to legacy tripcock mode, the driver simply switches over to TM Tripcock Manual mode, the tripcock will latch in, the colour light signal will show the traditional red and green aspects.
     
    Last edited: 20 Mar 2019
  8. bramling

    bramling Established Member

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    For those drivers who choose to drive manually, it’s simply a case of flicking a switch (known as the “scheme switch” - as in changing the protection scheme), and waiting for the train to adjust. If changing to ATO then it’s slightly more involved, as the master control switch must also be moved to the ATO position.

    The white lights indicate the train is ready to depart, and is the equivalent of the lunar white lamps found on the Jubilee and Northern lines. However, a word of advice, don’t be tempted to rely on these if walking along a platform to choose where to board - remember the driver can see a countdown in their cab, and on the other lines it’s not uncommon for drivers to close the doors a bit earlier in the countdown but before the train gets a limit of movement authority, which could leave people on the platform! Quite often this is one way of clawing back a few seconds for example at a terminus if departure time has passed and the train is simply waiting for something else to arrive and get out the way before the road is cleared.
     
  9. bramling

    bramling Established Member

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    Is it definitely the case that the tripcock arm lifts? On the Jubilee and Northern it was a fundamental part of the design that the trip cock remained fully operational. Hence trains were still getting tripped on footballs from time to time.
     
  10. ijmad

    ijmad Established Member

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    Do drivers have this choice for the moment on the SSR? I remember reading somewhere that on the Central Line, driving trains in coded manual tended to delay the service because even the best manual drivers just weren't as good as the computers at keeping up with the signalling system's target speeds.

    I guess this may not be an issue on the SSR for a while, until they do the speed and capacity uplift.
     
  11. bramling

    bramling Established Member

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    On paper, no. The expectation is that it’s primarily an ATO system and that is the normal mode of use, unless there’s an operational reason not to. There may be an exemption during the early days in order to allow drivers to practice if they so wish.

    However, in the real world, providing drivers can maintain time, and not have any form of incident (*) that wouldn’t have happened in ATO, no one really minds. Good drivers can quite easily maintain Thales ATO performance, and very good ones can actually very slightly surpass it. On the Central it’s also possible to keep up with it, albeit this requires driving very hard, and one has to consider there’s the risk of having a SPAD on the Central Line.

    (* Seltrac has an unfortunate design flaw that the train can lose communication with the system if the train experiences wheelslide, which can happen if the driver inadvertently has an over speed and the system intervenes to emergency brake the train. This will then cause a delay as the train has to be re-entered into the system. On the Jubilee and Northern this can take up to 10-15 minutes, although I believe on SSR it’s a bit quicker, a benefit of the radio system over the inductive loop cables. It’s this design flaw which is the main reason we see a pathetically low brake rate in the open sections, and this applies in ATO too. I’m not sure if SSR has bettered this, it’s still very much an issue in the Jubilee and Northern, despite a lot of work it seems that the low brake rate in the open is here to stay, with any attempt to uplift it pretty much abandoned. )
     
  12. philthetube

    philthetube Established Member

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    The S Stock is fitted with sanders, which should help with this problem.
     
  13. ijmad

    ijmad Established Member

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    Minor delays due to a faulty train earlier at Latimer Road. Coincidence, or did a train fail to switch to CBTC?
     
  14. Dstock7080

    Dstock7080 Established Member

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    Very much implied in training and CBTC Manual says:
     
  15. bramling

    bramling Established Member

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    Hmm. I don’t read it that way. To me it says this is preventing full-speed working in tripcock operating mode (effectively inhibiting full-speed manual operating). There’s nothing there which says to me that the tripcock itself is inoperable. They may well have done things differently from the Northern and Jubilee, but I have to say I’d be surprised. I guess we’ll find out before too long if something gets tripped on a foreign object!
     
  16. bramling

    bramling Established Member

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    Worth a punt on it being a tripcock relay mismatch. Not necessarily a fault with the train, another possibility is the driver has done something wrong (e.g. carry out the actions in the wrong order, or even too quickly).

    On the Jubilee and Northern it was a standing joke that the transition could go wrong just by the driver being too rough with the switch. The manufacturers of Hammersmith signal cabin’s frame would no doubt laugh at the flimsiness of Thales’s product!
     
  17. bluegoblin7

    bluegoblin7 Member

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    Train failed to switch back into legacy mode, with a TCP mismatch preventing full speed in tripcock mode.

    After attempts to rectify the fault failed, the train moved in restricted manual to Edgware Road.

    This is very much a train fault rather than a CBTC fault.
     
  18. bluegoblin7

    bluegoblin7 Member

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    S stock do not have a 'scheme switch'. All mode selection is provided from the MCS, including Auto, PM, RM and Tripcock.
     
  19. bramling

    bramling Established Member

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    Okay. I suppose that avoids the issue of doing the switches in the wrong order!
     
  20. Mojo

    Mojo Administrator Staff Member Administrator

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    Seemed to be a few problems with the service when I travelled from Hammersmith at about 16.00 this afternoon, overhearing from the project team on the platforms at Hammersmith that there was some blocking back through Latimer Rd Westbound awaiting Instructor Operators. When I entered the station all three platforms were occupied, with one stalled outside, one in the platform at Goldhawk Rd, one at Shepherds Bush (Market) and a second train stalled in section. The sidings at Hammersmith also had at least two trains in there as well one at Goldhawk Rd being detrained to go in there.

    When I arrived the indicator said Platform 3 was the next departure, to Barking; it was fairly busy even in the front car so I'm assuming there hadn't been a train for a while. After about five minutes the indicator said Plat 1 was the next departure, also to Barking, then this quickly flicked back to Plat 3. A PA was then made on the train, to say the first train to depart would be Plat 2, which ended up being a Circle train.

    Also noticed that at Shepherds Bush (Market) and Wood Lane the train seemed to stop on friction brakes; it was significantly quieter at stopping than normal.
     
  21. ijmad

    ijmad Established Member

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    Hopefully more of a people problem than a technology problem? (seems like those might be easier to resolve, in this case...)
     
  22. bluegoblin7

    bluegoblin7 Member

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    Largely just down to the requirement for Train Operators to be accompanied by Instructors for their first few trips - it's also been the reason for some of the delays over the weekend due to a shortage of operators. IOps have been released to cover these trips, but there's only so many of them to go round! There are fewer available today as the majority were required for the weekend.

    There are some teething problems, particularly with the CIS screens at Hammersmith, but these are all to be expected as the system beds into operation. These things can be tweaked as necessary to improve reliability/usability in a real world environment.
     
  23. ijmad

    ijmad Established Member

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    Travelled from Hammersmith to Wood Lane this evening, just for kicks.

    Things I noticed:
    • Train I was on stopped short at Goldhawk Road northbound, then moved slightly forward to the correct position. The train also made a very tentative approach to Wood Lane. I assume there's some tweaking of approach speeds still to do here and there.
    • The extra time between the train stopping and the doors opening isn't much, but it is noticeable, and seemed to throw some people off their usual rhythm. I imagine we'll easily get used to that though, it's no worse than many other lines and still a lot better than they seem to manage on Network Rail DOO trains.
    • A train birthed in the Southbound platform at Wood Lane had all its doors open but with the 'DOOR NOT IN USE' sign illuminated over each of the open doorways. Not sure what was going on there. It didn't seem to prevent the train closing its doors and moving shortly after the white lights illuminated. Gremlin in the system?
    Nothing major to report though, other than the novelty. Apart from the stop at Goldhawk Road the ride was very smooth.
     
  24. rebmcr

    rebmcr Established Member

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    Those could be ATO things, or just as easily Protected Manual things. It will be straightforward enough to determine which is which over time, once all of the PM practice runs quiet down.
     
  25. bluegoblin7

    bluegoblin7 Member

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    All of these are very much things that could (and have) present(ed) in both ATO and PM. Remember, PM is still in full communication with, and using, all of the CBTC kit.

    1 is something that will be tweaked with software as the system matures. Things like braking rates have been changed a few times over the weekend, and will continue to be adjusted. Trains will also stop short if they aren't 100% certain where abouts they are - it is always better to stop short and pull forwards than risk an overrun (or worse!). This is arguably no different to tripcock operation.

    2 is part of the system. The delay is shorter than that on the Jubilee and Northern lines, but won't be removed completely as it is an inherent part of how Seltrac works. I think it's been explained before, but briefly trains must communicate an 'Accurate Stop' to the system before it enables the door buttons. It isn't as quick as legacy CSDE, but it is arguably safer. Once full ATO is rolled out the additional time per stop should be negated by the fast run times and additional services.

    3 is a known train software problem that has been introduced with move to ATO. It is another of those foibles that will be ironed out. It isn't the first time this particular bug has occurred. It's an annoyance, but it isn't unsafe.
     
  26. ijmad

    ijmad Established Member

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    Thanks @bluegoblin7. That all makes sense, particularly No 3. Nothing too serious going wrong so far by the sounds of it!
     
  27. Dstock7080

    Dstock7080 Established Member

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    “DOOR NOT IN USE” signs are only provided in cars 1 and 7.
     
    Last edited: 19 Mar 2019
  28. Met Driver

    Met Driver Established Member

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    It is the same as TBTC on the Jub/Northern, i.e. the tripcocks remain in position and operative in the CBTC area. You can still be front tripped in the CBTC area and the train will EB regardless of driving mode. The latch relays simply relate to inhibition and enablement of tripcock driving mode, rather than the operability of the physical tripcocks.
     
  29. ijmad

    ijmad Established Member

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    Good point, I think I only got a good look at the first and last carriages, ironically.
     
  30. londonboi198o5

    londonboi198o5 Member

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    The tripcock does not lift on the s stock when changing from tripcock to CBTC. There is a tripcock relay switch that engergises and de-energises the tripcock. It will stay down all the time. This is because when a train enters the ATO area there a train stops placed at the migration boundary for safety.
     

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