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AOCL+B's on the East Suffolk Line

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Re: AOCL+B's on the East Suffolk Line

Unread postby Mike Hodgson » Thu Sep 11, 2014 5:30 pm

According to "Railway Control Systems", the flashing white at an AOCL should only be triggered if the road signals are correctly displaying flashing reds. The book is over 30 years old now so the circuitry may be out of date.

AOCL+B is conceived as a cost effective bolt-on to an AOCL, a modification that would be simpler if it does not have to check the position of the barriers. Adding barriers was seen as a safety improvement over the simple AOCL, so proving barriers down could have been considered an unnecessary complication leading to higher failure rates as well as cost

By contrast at an ABCL, the lowering of the barriers is an inherent part of the process which triggers the flashing white light. You would need substantial changes to the circuitry to do it when fitting barriers to an existing AOCL.

It will be interesting to see whether in time a decision is taken that this difference makes ABCL "safer" than AOCL+B, and whether AOCL+Bs are subsequently replaced by ABCL
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Re: AOCL+B's on the East Suffolk Line

Unread postby AN106 » Thu Sep 11, 2014 8:44 pm

This takes me back - "Stott mod" alterations to the East Suffolk Line level crossings was one of the first jobs I worked on in the drawing office, back in the early '90s. We were putting in the drivers red lights at the indication units, and I think some AOCLs were converted to ABCLs at the time.

It's many years since I did anything with these types of crossing, and I've never looked at the AOCL+B circuitry, but I'm surprised the driver's white light doesn't prove barrier down. Assuming the barrier machines have the usual detection controls, it would be simple enough to cut this into the relevant DWL circuit. The only reason I can think of is that it would delay the DWL from illuminating, beyond the point where the driver would have to brake for the crossing, thereby causing delays.
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Re: AOCL+B's on the East Suffolk Line

Unread postby Mike Hodgson » Thu Sep 11, 2014 9:32 pm

Yes. The time taken to get the barriers down as well the flashing reds will be longer, since the reds should be flashing for a few seconds before the barriers start. So the sequence needs to be initiated a few seconds earlier to get the white light in time. This means moving the strike-in point further out and you would be doing the calculations appropriate to an ABCL.
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Re: AOCL+B's on the East Suffolk Line

Unread postby AndyB » Fri Sep 12, 2014 6:57 pm

I think it may be to indicate that the circuitry has responded correctly to the train's approach. It could be that it is still tied to the timing that would have applied before the installation of barriers - but as ex Probationer points out, the driver is still required to carry out a visual check before passing the crossing that it is safe to do so.
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Re: AOCL+B's on the East Suffolk Line

Unread postby Mike Hodgson » Fri Sep 12, 2014 9:15 pm

Yes, but what is he supposed to check for - is he required to see the barriers fully down or is it sufficient that no traffic or obstacles are fouling the crossing? By the time the white light is flashing, the reds will have flashing and the barriers will have at least started to move so any vehicles should have pulled up.
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Re: AOCL+B's on the East Suffolk Line

Unread postby ex Probationer » Sat Sep 13, 2014 8:07 am

Mike Hodgson wrote:Yes, but what is he supposed to check for - is he required to see the barriers fully down or is it sufficient that no traffic or obstacles are fouling the crossing? By the time the white light is flashing, the reds will have flashing and the barriers will have at least started to move so any vehicles should have pulled up.


This is a link to the Rule Book - Level Crossings Driver's Instructions

http://www.rgsonline.co.uk/Rule_Book/Rule%20Book%20Modules/TW%20-%20Train%20Working/GERT8000-TW8%20Iss%206.pdf

The Anglia Sectional Appendix states that for an AOCL+B the instructions applicable to an ABCL apply.
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Re: AOCL+B's on the East Suffolk Line

Unread postby Mike Hodgson » Sat Sep 13, 2014 8:01 pm

Well, those instructions don't call for him to look at barriers under normal operation, so he can proceed as long as he hasn't been told of a failure, the white light is flashing and there's nowt on the crossing, even though the barriers, like the Grand Old Duke of York's men, are neither up nor down.
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Re: AOCL+B's on the East Suffolk Line

Unread postby AndyB » Tue Sep 16, 2014 6:36 am

That is correct, and section 4.4 lays down a very small number of conditions on any train proceeding as long as the crossing is clear irrespective of the state of the white light.

In a nutshell: the horn must be sounded in the case of white light failure until the front of the train goes onto the crossing, and at night, either the train must have all its internal lights on, any barriers must be down and working (including red lights), or somebody must be stopping traffic from proceeding over the crossing, presumably on both sides.
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Re: AOCL+B's on the East Suffolk Line

Unread postby Chris Osment » Tue Sep 16, 2014 11:49 am

Assuming that we are talking about the small red lights on the barriers, and given that - assuming not a skew crossing - they are aligned at right-angles to the railway, how is the driver supposed to see them all from distance? Do they give out sufficient light at night and does he know how many are supposed to be on each barrier?
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Re: AOCL+B's on the East Suffolk Line

Unread postby LlaniGraham » Tue Sep 16, 2014 2:37 pm

The red lights on the barriers are skewed to show down the road, not at right angles to the railway.
And they are noticeable!
(Well ours are at Bromfield)
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Re: AOCL+B's on the East Suffolk Line

Unread postby The Regulator » Tue Sep 16, 2014 3:53 pm

Some of the AOCL+Bs will only show the driver the white light once everything has worked correctly, road lights and the barriers are down. If only the road lights are going and the barriers have stayed up only the red light indication will show.
The whole process should take between 14 to 20 seconds to complete.
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Re: AOCL+B's on the East Suffolk Line

Unread postby Richard Pike » Sun Dec 14, 2014 8:31 pm

Seacroft LC near Skegness became AOCL+B Saturday night.
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Re: AOCL+B's on the East Suffolk Line

Unread postby ex Probationer » Sat Dec 20, 2014 1:48 pm

Mechy wrote:I have noticed over the past month or so that barrier pedestals have started appearing at just about all of the AOCL's on the East Suffolk Line (the only one with no visible work at present is Dawdys.)


I understand that Dawdys LC was the last of the twelve East Suffolk Line AOCLs to be commissioned as an AOCL+B. This occurred on the night of 18 December 2014. There are no longer any basic AOCLs operational on the Anglia Route as Althorne LC and Laundry Lane LC have also been changed to AOCL+B. Wisbech By-pass AOCL and Redmoor AOCL on the March to Wisbech Line are currently non-operational.
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Re: AOCL+B's on the East Suffolk Line

Unread postby AN106 » Sun Dec 21, 2014 9:39 am

ex Probationer wrote: Wisbech By-pass AOCL and Redmoor AOCL on the March to Wisbech Line are currently non-operational.

Google Street View shows that Wisbech By-pass crossing has been tarmacked over, and the wig-wags removed.
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Re: AOCL+B's on the East Suffolk Line

Unread postby Fast Line Floyd » Mon Dec 22, 2014 8:20 pm

The wig wags were still there in part as of 29th November as are the drivers level crossing indicators but these have been heavily vandalised and don't point where they should.

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