A780B

[rincew1nd]

A few months ago I bought this:

(A780^B by rincewindthefailedwizard, on Flickr)

for a silly price (never has a Yorkshire man had his hand in his pocket so quick). At the Christmas meet a few people suggested where it might have been from; does anyone out there have the definitive answer?

[railtechnician]

Most definitely NOT the Piccadilly line.
780 signals are the westbound multiple homes to Russell square, there is an A780^A but the ^B is FPX780^B.

[Deleted]

I'd go for the Met local line, I would go for about the Northwood/Northwood Hills area.......

[Deleted]

Not on the Met as JFX774 is Northwood Hills starter and A786 is north of Northwood all those between are semi auto's in the JF series.

[Tom]

I would suggest it's a signal that used to exist, possibly from the Piccadilly or District Lines prior to their 1980s resignalling.

[railtechnician]

Dec 30, 2010 10:45:07 GMT Tom said:

I would suggest it's a signal that used to exist, possibly from the Piccadilly or District Lines prior to their 1980s resignalling.

I must say I had had similar thoughts but I was thinking more of the Bakerloo and Central resignalling of the late 1980s and early 1990s. I only worked on the Central resignalling of the late 1970s as a wireman, Woodford/Queensway/Holborn/Chancery Lane/ St.Pauls and though I worked the whole of the 1980s Bakerloo resignalling my remit then was SPT and train radio renewal as part of the resignalling works and that signal number doesn't spring to mind.

If it had come from the 1980s Picc resignalling I guess it would have been from somewhere near South Kensington. I worked only from Cockfosters to Russell Square on stage 1 of that job in 1979.


Another thought was that it perhaps came from one of the old signal school layouts or perhaps even from the RTC.

[rincew1nd]

Thanks for the input so far, if it helps at all there are what look like hack-saw marks underneath the left-hand bolt hole, impinging onto the A.

[Deleted]

Dec 30, 2010 9:40:15 GMT @lnwrelectric said:

Not on the Met as JFX774 is Northwood Hills starter and A786 is north of Northwood all those between are semi auto's in the JF series.

Ah I see.....I was on my rest days and hadn't been on the line for a short while......must admit the Northwood area was first that sprung to mind.

[Tom]

Dec 30, 2010 14:11:03 GMT railtechnician said:

I must say I had had similar thoughts but I was thinking more of the Bakerloo and Central resignalling of the late 1980s and early 1990s.

I doubt it's ex-Bakerloo or Central, their signal numbers never went that high.
As for coming from the RTC or the Signal School, I would expect it to be in better condition like this example from the School:

[trainopd78]

A784 is a well known signal before Victoria on the Westbound. I cant get to my diagrams to confirm or deny if the plate was on the District before rationalisation.

[mrfs42]

Dec 30, 2010 22:40:34 GMT trainopd78 said:

A784 is a well known signal before Victoria on the Westbound. I cant get to my diagrams to confirm or deny if the plate was on the District before rationalisation.

Bingo! Sloane Square WB, 13th December 1956.

I'll dig out a picture of the peril in a bit....

[railtechnician]

Dec 30, 2010 22:07:42 GMT Tom said:

Dec 30, 2010 14:11:03 GMT railtechnician said:

I must say I had had similar thoughts but I was thinking more of the Bakerloo and Central resignalling of the late 1980s and early 1990s.

I doubt it's ex-Bakerloo or Central, their signal numbers never went that high.
As for coming from the RTC or the Signal School, I would expect it to be in better condition like this example from the School:

On the first point I had reached that conclusion. One thing I have never really known is whether there was a preferred numbering range for auto signals on a line but I have always assumed that there must've been from the point of view of shared tracks and four tracking as one wouldn't want the possible confusion of two signals with the same designation on the same route or on parallel routes. To some extent I assume that may be obviated by dropping numbers as is often seen although my assumption in that regard was always an allowance for expansion with the possible replacement of controlled with auto or introduction of additional signals, and yet that has sometimes been done by the addition of a suffix digit to an existing number to create a 4 digit designation. No doubt an area of design discipline firmly controlled by a suitable designation standard.

On the second point, I admit to 'clutching at straws' but if a rusty, bent or otherwise damaged plate is allowed to persist on the railway (as they certainly were, despite being reported) I would not discount the possibility of one being kept in a training environment.

[rincew1nd]

Dec 30, 2010 22:07:42 GMT Tom said:

As for coming from the RTC or the Signal School, I would expect it to be in better condition like this example from the School:

Is it worth noting that my dot is a square (vertical sides, horizontal top) rather than a diamond?

[railtechnician]

Dec 30, 2010 20:30:09 GMT rincew1nd said:

Thanks for the input so far, if it helps at all there are what look like hack-saw marks underneath the left-hand bolt hole, impinging onto the A.

Now therein tells a tale, on a resignalling changeover generally speaking nothing 'comes out' until the engineer in charge is satisfied that what has been installed is working as per specification. That is how it became but it wasn't always how it was, back in the day one's changeover notes (every wireman had a set for his piece of the work, as did the electrical and mechanical chargehands and the inspectors running the gangs) were comprehensive, what to disconnect, to connect, to cut out and remove etc for most changeovers done in a single Saturday night shift following a Friday 'visual' of what was to be done. A whole depot would be out on a big changeover and sometimes staff from several depots, some of the early changeovers that I worked on had more than 100 signalling staff working simultaneously.
This led to some catastrophic errors occasionally, one that I recall circa 1977/8 was at Leyton when we took out the old BR signal cabin lever frame, one of the mechanical chargehands inadvertently removed a 4 aspect size signal head which was meant to remain in service. Back then the method was for several strong men (usually the whole mechanical gang and one or two others to take the weight of the head as it was lifted off the signal post using a pulley and rope on the end of a long length (longer than the height of the post+head) of air main pipe. The head was far too heavy and bent the pipe under gravity as the head was lowered to the ground and there was no way it was going back up that shift!

Often on such changeovers time was at a premium and many things were 'cut off' rather than undone or dismantled. No doubt your plate was cut off from its mounting.

[mrfs42]

Dec 30, 2010 23:52:26 GMT railtechnician said:

. One thing I have never really known is whether there was a preferred numbering range for auto signals on a line

Yes - I've seen various overview diagrams that have been drawn and amended over the years with defined limits for the auto ranges with just the starting number; these were allocated in blocks of 50. In some cases these numbering schema were never actually allocated (Greenford and westward, after the idea of Greenford becoming the major intermediate turnback on that branch of the Central was quietly dropped) or changed (in the case of the unified District and Piccadilly series). IIRC, in both these cases, as I can't immediately find my notes.

Anyway, further to the original question:

[Tom]

Dec 30, 2010 23:52:26 GMT railtechnician said:

On the first point I had reached that conclusion. One thing I have never really known is whether there was a preferred numbering range for auto signals on a line but I have always assumed that there must've been from the point of view of shared tracks and four tracking as one wouldn't want the possible confusion of two signals with the same designation on the same route or on parallel routes. To some extent I assume that may be obviated by dropping numbers as is often seen although my assumption in that regard was always an allowance for expansion with the possible replacement of controlled with auto or introduction of additional signals, and yet that has sometimes been done by the addition of a suffix digit to an existing number to create a 4 digit designation. No doubt an area of design discipline firmly controlled by a suitable designation standard.

There is a drawing showing Auto signal numbering and their allocation - I don't remember the drawing number but I do remember it starting with 'BS'.
Four digit numbers are reserved for Auto draw-ups or Round the Bend signals, though there was a scheme produced a few years ago which featured four digit auto signals as a regular feature.

[Tom]

Dec 30, 2010 23:57:47 GMT rincew1nd said:

Is it worth noting that my dot is a square (vertical sides, horizontal top) rather than a diamond?

All that suggests is it's old.

[railtechnician]

Dec 31, 2010 11:06:32 GMT Tom said:

There is a drawing showing Auto signal numbering and their allocation - I don't remember the drawing number but I do remember it starting with 'BS'.
Four digit numbers are reserved for Auto draw-ups or Round the Bend signals, though there was a scheme produced a few years ago which featured four digit auto signals as a regular feature.

I recall there was a cabin print which showed the entire combine on a single sheet with all the allocated cabin letters including parts of the system which were never built, somewhere there is or was a drawing for everything. Mind you it's 25 years since I last saw that one.

I was aware of the four digit application to 'round-the-benders', I had a few of those in my maintenance area, but was not aware that it was applied to auto draw-ups. I thought PJ320 at Arnos Grove was such a signal or am I mistaken?

[trainopd78]

As far as plates on the District go, there seem to be many flavours, especially when it comes to multiple repeaters and dots.

[Tom]

I know the one, ES something or other. There are a small number of auto draw-ups, A2320 at Barbican, one at Cannon Street, and A5980 approaching West Ken. There is also the trainstop at Leicester Square (7590V?) but on the whole Auto draw-ups are more rare than controlled ones.

[Tom]

Dec 31, 2010 13:51:02 GMT trainopd78 said:

As far as plates on the District go, there seem to be many flavours, especially when it comes to multiple repeaters and dots.

Let's just say I've known the variations to catch a few Signal Engineers out too...

[Deleted]

Cannon St is A8400

[programmes1]

There was another A780B between Knightsbridge and South Kensington WB.

[rincew1nd]

Well I've only got one plate!

[North End]

Dec 31, 2010 19:13:21 GMT Tom said:

I know the one, ES something or other. There are a small number of auto draw-ups, A2320 at Barbican, one at Cannon Street, and A5980 approaching West Ken. There is also the trainstop at Leicester Square (7590V?) but on the whole Auto draw-ups are more rare than controlled ones.

A strange one is E.122, E.193, E.233 and E.234 at Camden Town. In some cases these numbers are a remnant of the original 1920s scheme.

As for automatic draw-ups, there's A.4160 approaching Brent Cross, and A.4340 (formerly ACX.4340) approaching Colindale. These two function more as speed controlled signals than draw-ups however.

Another two oddities are NN.14/15A and NP.16/20. In these cases 14 route and 20 route respectively allow the signal to clear if the train has been brought to a stand in certain situations.

[Tom]

Jan 3, 2011 0:03:26 GMT North End said:

As for automatic draw-ups, there's A.4160 approaching Brent Cross, and A.4340 (formerly ACX.4340) approaching Colindale. These two function more as speed controlled signals than draw-ups however.

Looking at the Scale plans, it seems that they function as speed controlled signals to permit the use of a short overlap on the relevant starters, but will also work as draw-ups if a train is in the platform ahead, in each case allowing a second train to draw up to the relevant outer home.

[railtechnician]

Jan 3, 2011 0:38:30 GMT Tom said:

Jan 3, 2011 0:03:26 GMT North End said:

As for automatic draw-ups, there's A.4160 approaching Brent Cross, and A.4340 (formerly ACX.4340) approaching Colindale. These two function more as speed controlled signals than draw-ups however.

Looking at the Scale plans, it seems that they function as speed controlled signals to permit the use of a short overlap on the relevant starters, but will also work as draw-ups if a train is in the platform ahead, in each case allowing a second train to draw up to the relevant outer home.

I'd be interested to know how you'd classify PJ3/500 and PJ4/600 at Arnos Grove, in function they seemed to act as autos when conditions were appropriate.

[Tom]

I'd probably classify them as normal controlled signals; the draw-up function was added later and only apply when there is a route set east from the other platform.

The auto nature of their operation may be due to the auto routing conditions in on the non-safety side more than anything else.

[railtechnician]

Jan 3, 2011 12:38:07 GMT Tom said:

I'd probably classify them as normal controlled signals; the draw-up function was added later and only apply when there is a route set east from the other platform.

The auto nature of their operation may be due to the auto routing conditions in on the non-safety side more than anything else.

I was never sure if they would be regarded as auto in appropriate circumstances.

[mrfs42]

Jan 3, 2011 0:03:26 GMT North End said:

Dec 31, 2010 19:13:21 GMT Tom said:

I know the one, ES something or other. There are a small number of auto draw-ups, A2320 at Barbican, one at Cannon Street, and A5980 approaching West Ken. There is also the trainstop at Leicester Square (7590V?) but on the whole Auto draw-ups are more rare than controlled ones.

A strange one is E.122, E.193, E.233 and E.234 at Camden Town. In some cases these numbers are a remnant of the original 1920s scheme.

Looking at the 1926 and 1924 opening notices it's not quite so simple as that: E 122 and E 193 are later additions and in both cases a lower number than the S signal protecting the platforms: S 194 for the Highgate branch and S 124 for the Golders Branch. At this time the S signal numbering didn't follow the later rule for Autos and tended to go round a line in a circle, rather than EB/NB Odd and WB/SB Even; IIRC the first line to be renumbered to the 'new standard' was the CSLR, but I can only find my notes as far back as 1921 ATM.

Likewise E 233/234 were not installed originally, these signals have either been moved or altered from E 40 and E 35 respectively. If I'm lucky I might have picked up the dates for these new or altered signals from the 1920s/early 30s UERL Traffic Notices, so I'll have a look through my notes on those, as there was some alterations in that period. Looking at the signalbox diagram itself it is very telling is that all four of these signals had a greek lettered berth track circuit adjacent to them: E 122 delta, E 193 phi, E 234 pi, E 233 theta; so these were permissive signals, I suspect.

What is clear is that the Northern has had various generations of different signal numbering, all of which have needed to cope with the fact that some of the signals haven't moved since they were installed on the northern and southern extensions. Additional autos would take the number of the auto in rear and have either 1 or 2 as the last digit: eg A 7091 between A 709 and A 711 southbound, north of South Wimbledon. An eminently sensibly way of doing it, so the AETs could make sense of the auto strips.

However, we've moved a long way off the original question. Looking at the typefaces involved, I suggest that the plate is off the District, not the Piccadilly; only a strong hunch though.

Jan 3, 2011 0:03:26 GMT North End said:

Another two oddities are NN.14/15A and NP.16/20. In these cases 14 route and 20 route respectively allow the signal to clear if the train has been brought to a stand in certain situations.

Indeed, NN 14/15A makes more sense when you think of a N frame driving the signals, rather than a V frame. There is a whole paragraph devoted to the permissive working of NN 14/15A in the 1939 peril for opening to East Finchley (Supp to TC 39/23) and another paragraph in the 1940 peril for opening from East Finchely to High Barnet (Supp to TC 40/13) about NP 16/20. Of perhaps tangential interest to this arrangement is that there were similar signals on the Central, installed as part of the transitional arrangements as the extensions were opening, but these were numbered in the auto series with the controlling signalbox prefix. The one I remember is something like LT 661.