mrfs42
71E25683904T 172E6538094T
Big Hair Day
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Post by mrfs42 on Apr 23, 2007 23:30:07 GMT
Can't prove why I think this - but is it something to do with Delta UA  - or at least that area? <wanders off thinking> Before the auto in the IR? Hmm. Or is it to prevent backtripping on the other road - reversing N-S Mets? Intrigued! Knowing my notes, I'm thinking of completely the wrong area. |
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Post by citysig on Apr 24, 2007 18:05:53 GMT
Errr... I know it's been a while, but you'll have to remind me of were that signal is.... Just to the south of Baker Street on the northbound Jubilee Line. To be honest the number escapes me at present (BMX---). I should know it off by heart as its normally one of the little quirks I get trainees to spot. The only reasonable explanation that has ever been given is that it is on the "fringe" of control between what is "our" signalling and the brief period the line is under the Bakerloo line control - albeit only utilising their IMR. There is no X signal on the southbound though. |
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Deleted
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Post by Deleted on Apr 24, 2007 18:30:23 GMT
Interesting - there was an X signal on the southbound once (BMX503d), according to Harsig's diagrams, but it must have been removed during the resignalling of either line (the Jubbly being done in 1984-1985, the Bakerloo in 1989-1991).
Is the signal numbered between 506 and 510?
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Tom
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Signalfel?
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Post by Tom on Apr 24, 2007 19:06:17 GMT
BMX258c.
The release downstairs is weird compared to the rest of the area, as it was a 2min one where the norm on the Bakerloo is 1min.
spent my first night as a lineman taking umpteen releases down there after changing an pair of WKRs, as I'm sure Citysig will remember...
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Post by Harsig on Apr 24, 2007 19:07:58 GMT
Interesting - there was an X signal on the southbound once (BMX503d), according to Harsig's diagrams, but it must have been removed during the resignalling of either line (the Jubbly being done in 1984-1985, the Bakerloo in 1989-1991). Is the signal numbered between 506 and 510? The existing IMR at Baker Street was brought into use in 1977. At that time the following X signals were provided. BMX396 Northbound Bakerloo BMX401A Southbound Bakerloo From Paddington BMX503A & BMX503B SB Bakerloo from Stanmore. By the time the Jubilee opened in 1979 all had been renumbered to A signals. The one X Signal Citysig is referring to is actually BMX258C on the northbound Jubilee but at the time of opening this was numbered A258C. So something strange has happened to cause this to be renumbered subsequently. |
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Post by Harsig on Apr 24, 2007 19:18:04 GMT
The explanation I heard for H & D comes from 'Home' and 'Distant'. Quite how it works, I'm not too sure (at least at this ungodly hour) I think I might go to bed and think this one over now, oh the joys of being on call... I'm now beginning to wonder if these actually come from American Practice. Quite by chance while waiting for my computer to boot up I was perusing a list of the signalling alphabet for both UK & US. Now the US go in for speed signalling quite a bit and consequently use different terminology and I discover that under the US meanings listed for D is 'procee D indication of a signal' which may be regarded as equivalent of a green signal in UK practice, while the meanings of H includes ' approac H indication of a signal' which may be regarded as the equivalent of a yellow signal in UK practice. |
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Post by Harsig on Apr 24, 2007 20:24:25 GMT
The release downstairs is weird compared to the rest of the area, as it was a 2min one where the norm on the Bakerloo is 1min. Perhaps it is because the IMR predates the others on the Bakerloo by about ten years? |
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Tom
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Signalfel?
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Post by Tom on Apr 24, 2007 20:41:28 GMT
Bascially, yes.
A horrible site for getting levers back normal. You can either operate the Delta, take a release, or lift the lock. Guess which one was most popular in engineering hours??!
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mrfs42
71E25683904T 172E6538094T
Big Hair Day
Posts: 5,922
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Post by mrfs42 on Apr 24, 2007 23:17:49 GMT
and I discover that under the US meanings listed for D is 'procee D indication of a signal' which may be regarded as equivalent of a green signal in UK practice, while the meanings of H includes ' approac H indication of a signal' which may be regarded as the equivalent of a yellow signal in UK practice. I'd still put in a vote for the American influence by dint of the word approach, it is still used these days for 'approach medium', 'approach clear' and 'approach restricted'. IIRC British terminology always used 'approach' in the sense of 'getting near to the signal' rather than 'how fast can I legitimately hoon it towards the stick' ;D |
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mrfs42
71E25683904T 172E6538094T
Big Hair Day
Posts: 5,922
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Post by mrfs42 on Apr 24, 2007 23:32:34 GMT
So something strange has happened to cause this to be renumbered subsequently. A258 CAh. Thought I was in the wrong area. I'd hazard a guess that it is related to 11 points or the removal of R504 in 1977 and replacement with 2 R5041s (one au natrel and one under BM10). Mind you; what's the ALR distance on BM12? Just a thought.... |
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Post by mandgc on Apr 25, 2007 6:21:37 GMT
Distant Signals.
I think the practice of controlling the Distant Signal remotely by wire and indicating by means of the interlocking when off that the line was clear through to the next Signal Box was introduced in the 1860s.
I'd like to think that this sophistication was not in used on US railroads at that time.
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Post by mandgc on Apr 25, 2007 6:36:51 GMT
"Approaching"
British Railways used the expression "In rear of" to describe the approach from the the Signal Box behind the train and "In advance of" to describe the line towards which the train is proceeding.
The expression "Approach controlled" was used to indicate that a signal would not clear until the train had come within a certain distanceof the signal for speed control reasons.
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- or at least that area?
