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signal box bell codes

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duncan webster12/06/2018 23:59:58
2792 forum posts
41 photos

I've been reading a book on the development of railway signalling. Very interesting, but perhaps that says something about me! I've understood it ok, but one thing I'm not sure of. When a signalman offered a train to the next box, he sent a code telling the next in line what kind of train it was. Why did the next man need to know? Surely provided his section was clear he had to accept trains in the order in which they were offered? The only way of not accepting seems to have been to not reply.

Brian Sweeting13/06/2018 00:09:09
442 forum posts
1 photos

I'm no expert but I believe it depends of the possible length of clear line available for safety spacings.

Does info here help at all?

Edited By Brian Sweeting on 13/06/2018 00:09:38

julian atkins13/06/2018 00:19:54
1235 forum posts
353 photos

Hi Duncan,

This is quite an involved topic. It was vitally important for the box receiving a train to know what type of train this was on absolute block working with double track and refuse sidings and loops etc and also possibly relief lines.

A slow 'fly' goods might hinder an express service. Suggest you read the report on the Quintinshill disaster.

When I worked on the railways in South Wales on The Valleys, the bell codes were still as per GWR despite no freight then being worked, but we had light engine movements when we worked LHCS, and ECHS workings, failures in section etc. Although no freight, we had track cleaning trains, and also engineers trains from NR.



Ady113/06/2018 01:25:47
3852 forum posts
522 photos

Surely provided his section was clear he had to accept trains in the order in which they were offered? The only way of not accepting seems to have been to not reply.

Some stuff is straight through high priority, others are general or low priority and may need to be sidelined to wait for the express/military/Royalty train whatever

ding ding

It's pretty amazing stuff to watch/listen to, youtube probably has footage

Gas_mantle.13/06/2018 01:43:45
359 forum posts
269 photos

I'm an ex railway signalman of 30yrs.

By understanding what train was being offered the advance signalman is able to decide to accept or refuse the train dependent on the situation within his own area of control. He may for instance operate a junction, sidings, good loops etc and before accepting a train he needs to know which way it is going at a junction and whether it can refuged in a loop etc

In a simple signalbox with no junction etc the signalman is pretty much compelled to accept the train in the order they are offered but in the case of complex junctions he may want to accept trains in a specific order to avoid delays, congestion etc

Gas_mantle.13/06/2018 09:48:56
359 forum posts
269 photos

When I first started working on the railway I bought a copy of this book, it's an excellent read for anyone interested in signalling :-


duncan webster13/06/2018 10:17:12
2792 forum posts
41 photos

I think that's the one I read, got it from the library, very good book.

Thanks to all who replied, I'd forgotten about junctions, passing loops etc, where the receiving signalman might have to prioritise or decide what to do with a train once he'd accepted it.

Neil Wyatt13/06/2018 17:35:09
18226 forum posts
714 photos
77 articles

> The only way of not accepting seems to have been to not reply.

That seems to be a 'fail safe' system!

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