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Longest axle counter section

Current and future British signalling (UK except Northern Ireland)

Longest axle counter section

Unread postby AN106 » Mon Feb 13, 2017 9:26 am

The single line between Nairn and Inverness appears to be controlled by some form of TCB, with the bulk of the line being a single axle counter section between approximately 129MP and 143MP - a distance of 14 miles. Obviously unlike conventional track circuits, there's no limit to how long they can be. Is this the longest in the UK, or does anyone know of anything longer?
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Re: Longest axle counter section

Unread postby Signal-sighter » Wed Feb 15, 2017 10:37 am

It's not "some form of TCB" - it is TCB.
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Re: Longest axle counter section

Unread postby Mike Hodgson » Wed Feb 15, 2017 1:55 pm

I can't help thinking TCB should be renamed given that it doesn't necessarily use TCs any more.
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Re: Longest axle counter section

Unread postby S&TEngineer » Wed Feb 15, 2017 3:13 pm

Mike Hodgson wrote:I can't help thinking TCB should be renamed given that it doesn't necessarily use TCs any more.

I don't agree with that. Regardless of the method of train detection the signalling system still behaves as though its TCB. Unlike some places on the continent, the signallers here don' get any axle count information.
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Re: Longest axle counter section

Unread postby colin1501 » Wed Feb 15, 2017 5:04 pm

In one way though, axle counters are more akin to AB than TCB. Track circuits give continuous detection while the train is occupying them. Axle counters effectively provide confirmation of the train entering the section and leaving the section, providing the counts are the same. In between, the system has no idea whereabouts in the section the train is.

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Re: Longest axle counter section

Unread postby Richard Lemon » Wed Feb 15, 2017 5:16 pm

In France it is "Automatic Block" (translated) - far more logical. Calling it TCB can confuse, I suggest. TC Operating Clips are of no use, but a member of train crew may use them and think he is protected. Perhaps this should be part of Route Knowledge, or some indication given.

OK, Hornets nest stirred!

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Re: Longest axle counter section

Unread postby JRB » Wed Feb 15, 2017 10:57 pm

How many staff have been sent for axle counter clips on April 1st?
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Re: Longest axle counter section

Unread postby Mad Mac » Thu Feb 16, 2017 4:52 am

Richard Lemon wrote:In France it is "Automatic Block" (translated) - far more logical. Calling it TCB can confuse, I suggest. TC Operating Clips are of no use, but a member of train crew may use them and think he is protected. Perhaps this should be part of Route Knowledge, or some indication given.

OK, Hornets nest stirred!

Richard


I have a distinct recollection of a sticker on DMUs adjacent to the clips saying "Use Track Circuit Operating Clips First". I believe the training given to traincrew didn't make the distinction between a "regular" TC and a counter.

On the original subject of length, I believe the long-superseded one between Carstairs and Midcalder was around the 15 mile mark.
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Re: Longest axle counter section

Unread postby Signal-sighter » Thu Feb 16, 2017 10:45 pm

Train crew are required to place TC clips as their first action when carrying out emergency protection regardless of the method of signalling. Though thee days there are very few occasions where the Rule Book requires emergency protection be carried out.
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