Piccadilly Line part suspended due to leaf fall today

[Mikey C]

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/

We have taken the decision to temporarily suspend the Piccadilly line between Rayners Lane and Uxbridge between 17:00 and 21:00 today, Friday 15 November. This is due to expected high leaf fall, which makes the tracks slippery and increases the risk of damage to train wheels.

Trains will continue to run from Rayners Lane along the rest of the Piccadilly line. The Metropolitan line will run as normal.

To maintain a safe service during the leaf fall season we have been running special leaf-clearing trains, applying adhesive gel to the rails and putting speed restrictions in place on sections of the track. However, as significant leaf fall is expected in that area tomorrow we feel it is necessary to close this section of the Piccadilly line. To find out more about how leaf fall affects our trains and what we are doing, visit our blog post about leaves on the track.

We continue to take steps to prevent further impact to your journeys but we may have to suspend this section of the line again, so wherever possible please check before you travel, consider alternative routes and allow more time for your journey this Autumn.

Thank you for your patience and we are sorry for the disruption this will cause to your journey.

Yours sincerely,

Customer Information Team
Transport for London

 

[goldenarrow]

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.

 

[Dstock7080]

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

 

[sprunt]

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?

 

[bluegoblin7]

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).

 

[Mojo]

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?

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.

 

[sprunt]

Thanks for the answers.

 

[bramling]

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?

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!

 

[Lewlew]

Does the S Stock have sanders?

 

[Dstock7080]

Does the S Stock have sanders?

Automatic sanders (not under driver control) for CBTC areas yes.

 

[Lewlew]

Automatic sanders (not under driver control) for CBTC areas yes.

Ahh I see, thanks

 

[Dstock7080]

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.