Piccadilly Line part suspended due to leaf fall today

Discussion in 'London Underground' started by Mikey C, 15 Nov 2019.

  1. Mikey C

    Mikey C Established Member

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    Just got an email from TfL, informing that the Piccadilly Line between Rayners Lane and Uxbridge will be suspended due to leaf fall this evening between 17:00 and 21:00.

    The Metropolitan Line trains will still be running, it seems the 73s struggle more!

    https://madeby.tfl.gov.uk/2019/10/07/leaves-on-the-track/

     
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  3. goldenarrow

    goldenarrow Member

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    It's good at least that this is the first year where there has been a concerted effort to mitigate the risk of wheel damage to the fleet. Even with aggressive push back of vegetation, reduced speeds and dedicated RAT's, the fleet is still very vulnerable. With no prospect of this ageing fleet being given a permanent fix, I'm sure this will become a regular fixture for the next few leaf fall timetables.
     
  4. Dstock7080

    Dstock7080 Established Member

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    Also suspended a few Saturdays ago, as one of the ‘73 RATs derailed at Acton Town in the morning.
     
  5. sprunt

    sprunt Member

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    I'd heard of leaves causing slippage before, but how do they damage wheels?

    Also, are the Met line trains designed to be more resilient to leaves due to spending more time above ground?
     
  6. bluegoblin7

    bluegoblin7 Member

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    When braking, leaves can cause trains to slide, with the wheels locking up and ‘flats’ being made on the metal wheels. If these become too big or numerous, trains have to be taken out of service.

    The Met line is more resilient simply through being more modern trains and having a bit more slack; the same amount of mitigation is applied on the Met main as it is on the open sections of the Piccadilly (and indeed Central).
     
  7. Mojo

    Mojo Administrator Staff Member Administrator

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    There is both wheel slip and wheel slide. The former is when the wheel is turning but the train is not moving as fast (or at all), or the latter is when the wheel is not turning as fast (or at all) as the train is moving. Effectively, the wheel is being ground down against the rail creating a flat spot.

    It is purely down to the fact the S Stock has more modern features and thus can cope with low rail adhesion better than the 1973 stock.
     
  8. sprunt

    sprunt Member

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    Thanks for the answers.
     
  9. bramling

    bramling Established Member

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    The S stock has a protection system (WSP) like all modern trains. This doesn’t completely eliminate flats but it does reduce the likelihood by repeatedly and momentarily releasing the brakes on a given wheelset if slide is detected in an attempt to get them turning again, a bit like ABS on cars. It’s not possible to completely overcome the laws of physics though. Compared to A stock the S stock is much better though, on A stock flats were pretty much standard at this type of year whereas on S stock they are the exception.

    73 stock IIRC did have a rudimentary WSP system when new, but I think it fell into disuse quite quickly.

    From memory I think I’m right in saying the 96 stock was the first to have a WSP system in the modern sense. 92 stock IIRC was retrofitted after a massive outbreak of flats and overshoots around time the new signalling came in!
     
  10. Lewlew

    Lewlew Member

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    Does the S Stock have sanders?
     
  11. Dstock7080

    Dstock7080 Established Member

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    Automatic sanders (not under driver control) for CBTC areas yes.
     
    Last edited: 25 Nov 2019
  12. Lewlew

    Lewlew Member

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    Ahh I see, thanks
     
  13. Dstock7080

    Dstock7080 Established Member

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    No Piccadilly services Rayners Lane-Uxbridge until 0900, then 1600-1800 tomorrow 7 December “due to expectation of high leaf fall”.
    Metropolitan to run normally.
     

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