'Homes' Terminology

But that installation is atypical, as the last two homes are linked to the same track circuit pattern and clear simultaneously. I believe you said it was because home #3 protected the trailing points of the crossover that once existed there, while home #4 protected the platform, and when the crossover was lifted, two signals were no longer needed.

This is known as 'multi-home' signalling - (as previously mentioned by aetearlscourt) the first signal is the outer and the last is the inner.............all others in between are simply called intermediates.

Nope! Junction signals are only used at a diverging junction - not where two (or more) routes converge.

If it's on it's own, it's simply a Home signal.

The last signal before a station is the Home signal - you will only get Outers, inners, etc where other signals are associated with this signal.

I think you are trying to overly complicate things here

Intermediates would be associated, yes - if they're not associated then it's not a 'multi-home' signalling area.

Indeed we do - an advanced starter is the first semi automatic (controlled) signal after the station starter.

OK, let's see if I can have a go at this:

Numbering

Semi-automatics (controlled) have a cabin code followed by one or two (and sometimes three or four) numbers. The numbers are the lever numbers.

Automatics have a letter 'A' (or 'S' on parts of the Northern Line) with up to four numbers after it.

'X' signals are automatic's, usually the last automatic before entering a controlled area (there are many varied exceptions to this though). 'X' signals are treated as semi-automatic's by drivers and therefore cannot be passed without authority from the signaller in times of failure.
There are various types of 'X' signal:
"Normal" 'X' signals will carry the cabin code of the area immediately after it, along with it's automatic number in line with the that given line's numbering system.
PNX signals protect possessions - automatic signals are re-numbered temporarily.
FDX, for example, is a an 'X' signal protecting a floodgate - in this case on the District line. F= floodgate & D=District, other lines will use a different letter instead of 'D' - or as is often the case with LUL, a different numbering system altogether

Signal Names

I have hopefully described Homes well enough, and I've established what an advanced starter is......................

A running signal is an automatic signal which is not a Home or station starter.

A junction signal is only used on the approach to diverging points, and will always be a semi-automatic (controlled signal).

A draw-up signal is associated with a semi-automatic (controlled) stop signal, and will usually have a zero added after it's associated signal's number - so for example, on approach to Tower Hill eastbound, we have EJ1 (the bay road junction signal) with EJ100 (it's associated draw-up) just before it. Draw-up's are generally used to protect junctions and allow trains to get closer at a reduced speed, thus keeping trains moving safely.

Ermm..........ok, I've run out of puff (plus I need to get ready for work soon - Hmm..........nights ;D ;D).

I hope that helps.

Nicely typed, COLIN - I didn't feel like typing all of that out myself, as I knew I would inevitably miss something! ;D

Seriously though, with regards to X signals, is it not the case that sites with global releases number the second automatic signal in rear of the first controlled signal as an X signal? Turnham Green is a good example - on the west you have A584a, A584b, WKX582, A580, WK50a, WK50b, WK48; on the east you have A563a, A563b, WKX563c, A565, WK1.

Queen's Park is a bit of a mystery to all who have to work on the site - trust me!

The design of the lever plates and the writing of the yellow peril may have been done by different people who probably used different terminology for the same thing - quite why I don't know.

The yellow peril sounds quite interesting though - I've been involved in establishing why those draw ups were installed (as they were pre-existing at resignalling in 1989) and I'd be quite interested to have a look at it at some stage.

Incidentally BB1 is now BB35 and BB3 is now BB340.

That might be because other levers may have been controlling the outer homes - though without a diagram it's difficult to say for sure.

I've often wondered why the X signals here had an auto after them - I thought I was going mad!!

I can't answer the technical point, but it's certainly an interesting question all the same One for aetearlscourt I think..........

No problem - I find signalling interesting, so it's a pleasure to be able to speak about something I have some knowledge on

As you mention elsewhere, these terms are used in old notices - perhaps it was just the terms that were used back then.........or as Tom suggests, maybe the person that wrote them used different descriptions / terms to everyone else They're certainly not used as part of today's terminology.

The type of station starter (ie, auto or semi-auto) is irrelevant - if the next signal after the station starter is a semi-auto, it's an advanced starter. If it's an auto, it's a running signal

Not at all - ask away!!

As an aside, I wonder if TOK has noticed a rather strange anomaly at Gunnersbury - mind you I only noticed yesterday and I've been driving on the line for almost three years ;D

The Gunnersbury westbound (down) station starter (GB9) is an automatic signal - but trains can reverse back east (up) using the controlled signal at the other end of the platform (GB6) **there's another for you mrfs42 - that's called a 'wrong road starter' **. I always thought that in such circumstances, both signals must be of the controlled type to prevent a 'mishap'

Any thoughts on that TOK?

It was one of the first things I noticed when I became interested in signalling!

I suspect that, as Oracle suggests, it was felt that any train reversing at Gunnersbury would have a traincrew aware of this fact and thus be capable of ignoring GB9 when arriving in the station. Keep in mind too that until relatively recently, any train running onto that part of the District had guards as well - these guards would undoubtedly act as a backup to ensure that a reverser did not proceed beyond GB9.

I do agree though that having an auto at one end of a platform and a controlled stick at the other could result in a rather undesirable scenario of having green signals at both ends! Based on my somewhat extensive reading of LU signalling diagrams, I guess it is simply an LU signalling principle to make the signals at both ends of a platform controlled sticks when a crossover is present at one end or the other.

However, there are actually two anomalies at Gunnersbury - the second is that GB8 rte 2 always clears straight to green with a No.4 harbour light when the route is set for the District, despite the fact that WK11a is almost always red. GB8 rte 1, OTOH, is capable of clearing to single yellow when the route is set for the NLL.

That is indeed an LU principle - I'm fairly sure that quite a bit of jigging around with signals was done with extra crossovers - Lords f'r 'zample.

In a platform, the GR of the controlled stick would break the feed - ISTR this is 'alternate red', tho' I may be wrong - to the GR of the auto.

As I understand it the provision of X signals immediately before a controlled area is to prevent the first semi automatic signal remaining approach locked after the normal passage of a train because the following train has applied the rule at the last auto and drawn up behind the first train. It therefore follows that the X signal should be the last automatic signal before the train reaches the point at which the first semi-automatic signal becomes approach locked. There may or may not be other automatic signals in the intervening distance between the approach locking point and the semi-automatic signal. Examples of both can be found all over the system.

Indeed it is. It is generally found at older sites where a global release is provided, or where releases aren't provided.

As we now have selective (automatic) releases, the need for X signals approaching a controlled area has gone.

I must say I'm finding this thread very interesting.

Would it be possible for someone to explain the acronyms GVCR, GVPR and GC?

I've had a quick Google and search through past threads but haven't managed to find anything but this may be because I lack Colin's searching skills.

Mayhap I can help - the signalling circuits I work with use British Standard 376 part 2: wiring symbols and written circuits - (part one is plan symbols). There is the 'signalling alphabet'.

G (as a general signal relay) comes from siGnal, R is for Relay, P comes from rePeating, trainstop as V comes from when America started using W for SWitch - as in a NWKR - Normal SWitch Indication (K is a homophone for C) Relay. For the best explanation I can come up withV was the next available letter in the alphabet. (for the non-geeky: a NWKR is an relay that indicates the normal position of a set of points)

What really can be confusing is the use of D for a relay that creates a green aspect - makes sense when you see green as Decoding. I've never worked out why 'H' for yellow or 'Y' for disengaging. UECR for RoUte Lamp (Electric Lamp ) Checking Relay - used in Arbour lights - the use of E doesn't make sense at first sight. Y for a YR - slotting or disengaging relay doesn't make sense - unless Y comes from "Yes, you can use that signal."


A Back Contact is made when a relay is 'down' - deenergised, i.e. normally closed. Front - normally open contacts - are made when the relay is 'up' or 'picked'. Back/Front comes from when relay contact arms had a horizontal swing to them or the energised contact connections were made at the front of the relay top when you looked at them - 'down' contacts come from horizontally pivoted relay arms and are made when the relay has no current flowing through it - you'll occasionally see the phrase 'cold proving' which uses back contacts - ANY red aspect will always be given by a back contact as the last contact in the circuit. I spent many a long hour in my teens working with fishbowl shelf relays.

I'm wittering away - apologies one and all. I'm prone to thread drift..... ;D ;D

That one is straightforward - *well* sorta straightforward after thinking on your suggestion.

D comes from Danger - a DR (relay that gives a green when up) will give a red when down. A combined signal red/yellow/green or one of the 3-position semaphore types as used at Ealing Bdwy in the past would colloquially be known as a 'Home and Distant' - at least aroundabout 1910 - 20 ish when this alphabet started to come into existance.

It made more sense to keep the D for Danger - as signalling is more to do with stopping trains - signals that would have been a combined Home/Distant would have had 2 relays (one for the yellow, called the HDR; and one for the green called the DR). Over the years the D in HDR dropped out of use.

A lot of this comes from how the Americans chose to label things - after all they were the market leaders in mass installations.

I remember it well ;D



Except of course, the one X signal we have at Baker Street which is within a controlled area which has selective releases ;D