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Leaf fall control

Discussion concerning level crossings

Leaf fall control

Unread postby Sethu69 » Mon Jan 16, 2017 5:29 am

I would like to know if there are any standard controls applied at level crossings for Leaf fall issue and list of Level crossings where such leaf controls are applied.

Thanks.
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Re: Leaf fall control

Unread postby Fast Line Floyd » Mon Jan 16, 2017 7:14 pm

Sethu69 wrote:I would like to know if there are any standard controls applied at level crossings for Leaf fall issue and list of Level crossings where such leaf controls are applied.

Thanks.

If you are talking about a technical solution rather than procedural then the answer is no. If however the answer is procedural then I believe there are some.
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Re: Leaf fall control

Unread postby Sethu69 » Tue Jan 17, 2017 5:09 am

Fast Line Floyd wrote:
Sethu69 wrote:I would like to know if there are any standard controls applied at level crossings for Leaf fall issue and list of Level crossings where such leaf controls are applied.

Thanks.

If you are talking about a technical solution rather than procedural then the answer is no. If however the answer is procedural then I believe there are some.


My query was regarding both, technical and procedural. I want to know the level crossings where leaf fall issue is prevalent and the controls applied as mitigation. This will help me to study further to know if any consistent practice was followed.
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Re: Leaf fall control

Unread postby Fast Line Floyd » Tue Jan 17, 2017 1:39 pm

Sethu69 wrote:
Fast Line Floyd wrote:
Sethu69 wrote:I would like to know if there are any standard controls applied at level crossings for Leaf fall issue and list of Level crossings where such leaf controls are applied.

Thanks.

If you are talking about a technical solution rather than procedural then the answer is no. If however the answer is procedural then I believe there are some.


My query was regarding both, technical and procedural. I want to know the level crossings where leaf fall issue is prevalent and the controls applied as mitigation. This will help me to study further to know if any consistent practice was followed.

Procedural is to put AHB's and CCTV crossings with auto lower into non stopping train mode (where provided) for all trains so that if a train has trouble stopping at the protecting signal the crossing will already be down.
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Re: Leaf fall control

Unread postby Mark Lamb » Tue Jan 17, 2017 8:20 pm

Additionally at automatic crossings (i.e. AHB, AOCL, ABCL), at the strike-in point for commencing their sequence two methods are used. One is by occupation of track circuit by the train (and hence suspect to leaf fall issues); the second is by operation of a treadle (by the wheel flange and thus not suspect to leaf fall issues). There are - or were - exceptions to this, principally on older crossings where occasionally treadles weren't provided, or conversely where track circuits weren't aligned with the treadles. There can't be many of these left now, if indeed any?

One of the MCB (CCTV) crossings on the Barnes to Richmond line (Mortlake?) was fitted with leaf fall protection when control was passed from Barnes SB to Wimbledon PSB. If my memory serves me correctly this consisted of a switch operated by the signaller in leaf fall season. This brought into use a series of detectors that would initiate the closure sequence of the level crossing (red road lights only) if a train was approaching too fast (i.e. sliding) and could therefore run past the protecting signal and onto the crossing. I don't know if it's still in use as it wasn't too long ago, but it did predate current protection measures and so may have been superceded by newer instructions.

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Re: Leaf fall control

Unread postby AN106 » Wed Jan 18, 2017 7:48 am

When we renewed Addlestone Crossing in the late '90s it had a similar control. The layout for the Down Chertsey line from Chertsey through Addlestone station had treadle A at the start of the station platform and treadle B approximately 55m after that. The crossing is at the Weybridge end of the platform, protected by 905 signal, with overlap track AWD. I still have a copy of the crossing diagrams, and there is an explanatory note on them which states the following:-

Addlestone road lights sequence is initiated if:

i) The time elapsed between a train activating treadle A and treadle B is less than 3.5 seconds (i.e. the average speed across this distance is greater then 35mph); or
ii) A train activates treadle A if the poor adhesion run-by protection facility has been initiated; or
iii A train occupies track 'AWD' having run by signal 905 at danger.

I don't know if these controls are still in place, or if the poor adhesion facility was ever used.
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Re: Leaf fall control

Unread postby Sethu69 » Wed Jan 18, 2017 9:09 am

Many thanks to Graham, Mark and AN106 for all the inputs.

In Mortlake crossing records, I find the RTL initiation conditions are similar to Addlestone mentioned above.

I would like to know a crossing (manned barriers) is expected to behave ( RTL, Barrier lowering etc.) under poor adhesion control enabled( leaf fall) or Stowmarket control or SPAD predicted conditions? - Similarities and differences. Is it possible to have a common approach so that road user ( as well as Signaller) will see identical display under all these conditions?
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Re: Leaf fall control

Unread postby Fast Line Floyd » Wed Jan 18, 2017 6:37 pm

The controls mentioned for Addlestone and Mortlake were standard controls for run by protection where the platform starting signal is close to the level crossing as opposed to leaf fall protection although of course they achieved that as well.
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