Page 2 of 2
Signal Time Out 07/12/2023 at 03:40 #154636 | |
GeoffM
![]() 6344 posts |
Basingstoke extracts - chopped the 1 off the 120 for B(M), sorry! Post has attachments. Log in to view them. SimSig Boss Log in to reply |
Signal Time Out 07/12/2023 at 07:35 #154637 | |
clive
![]() 2766 posts |
This thread has led me to look at the control tables for Cambridge interlocking. While most of the signals are approach locked "when ready to clear", there are some interesting exceptions. CA145, where the Down Slow branches off the Down Main on the approach to Cambridge, is simple approach locked on the route to the Down Main but is comprehensively locked on the route to the Down Slow. The latter route is approach released when a train enters the track circuit after the overlap of CA143. Both have the same time (3 minutes). CA647 (up to down reversals on the Up) is comprehensively locked by the berth track circuit. This signal is only used by reversing trains, so I would have thought if it was pulled at any other time it would be more than 30 seconds before a train would be around. But I suppose it allows the Up to become available faster if a route was set accidentally, since it's not approach released (to my surprise). CA655 (facing shunt on the Up) has three routes, each with a complicated arrangement I've never seen before. There are two separate approach locking entries for each route: (1) locked by the berth track circuit, timeout 30 seconds, locking released on first TC after the signal occupied and cleared and second TC occupied; (2) comprehensively locked back two signals, locking released when train passes, time release "NIL", requires route from the signal in rear normal. I can safely say that I don't understand that. Log in to reply |
Signal Time Out 07/12/2023 at 09:09 #154639 | |
kbarber
![]() 1723 posts |
[quote=Izzy;post=154616<snip> And if you want really restrictive - in the old days when Margate had it's lever frame, there was no approach lock release cicuitry or timers - if the signalman pulled off in error, then he had to get the S&T out (at least, officially). I am sure this wasn't unique in older interlockings - and every signalman i ever knew who signed Margate was very aware of this trap!!! <snip>[/quote] This was also the case in the boxes (Clapham B - East Croydon) of the 1950s resignalling of the Brighton line London area. Those were all Westinghouse L frames and the S&T were clearly well versed in giving releases when needed (it could be quicker, IIRC, than a standard timeout). I must admit I'm not sure what the situation was at Battersea Park (another L frame, but installed in 1938). I'd be interested to hear if you know when the Margate setup dated from. Log in to reply |
Signal Time Out 07/12/2023 at 12:40 #154640 | |
clive
![]() 2766 posts |
TUT in post 154632 said:No points in advance of that signal are in the overlap at all and can be moved at any time with a train approaching the signal. If the calling-on were to come off I see no reason why any of them should become locked for 240 or even 120 seconds.I suspect you're thinking of a train overrunning the signal but stopping in the overlap. You should think in terms of a driver misreading the aspect and proceeding at speed through the route. The idea is to give the train either time to stop (or be so slow it clearly will stop) or to get past the signal before the timer expires, which will then hold the route so that the train can progress through it safely. Log in to reply |
Signal Time Out 07/12/2023 at 12:44 #154641 | |
clive
![]() 2766 posts |
Izzy in post 154629 said:Quote:True, you'd need to propagate the route class through. There might be occasions where it's easy (e.g. shunting exit merging with the main line right before the signal), but usually it'll at least need a couple of relays extra.Yes, but the route class in rear is lost as the train enters that route, the entry route "class relay" (MER, SER, MER(C), (M,S,W or C) NLR, amnogst others depending on interlocking type (not exhaustive) ) begins to release that route behind the train as soon as it replaces the entry signal. So, the signal that you pull the button on in many cases has no way of knowing what class route was set up to it. Hence we use the longest, worst case, timer length. Quote: Very true. Log in to reply |
Signal Time Out 07/12/2023 at 16:06 #154642 | |
Izzy
![]() 44 posts |
It seems the world moves on as we get older - so some things have changed, thanks for the examples Geoff - especially that one at Basingstoke. I'm so glad i don't need to keep on top of it anymore since i retired. Kbarber - i'm not sure of when the Kent Coast phase 2 was actually commissioned, but that is the incarnation of Margate that i was talking about - my guess is mid to late 1950's. Basically it was one of two boxes relocked to signal the whole Margate area utilizing the existing lever frame in Margate "A" box- replacing all the mechanical equipment with colour light signals and electric point machines. Most boxes treated like this had some sort of route release timers - but for some reason i don't know, Margate didn't have them. The Brighton mini-lever frames were actually a generation older than the Kent Coast Phase 2 Margate, so possibly had even more diffeent ways of working. One thing i am certain of though....many signalmen were familiar with how to help themselves to a release on the K and L type frames (many have told me stories of this). You just had to know where to stick your fingers in... Log in to reply The following user said thank you: kbarber |
Signal Time Out 07/12/2023 at 16:23 #154644 | |
TUT
![]() 514 posts |
19th July 1959 I believe for closure of Margate B and final transfer of everything over to A (although of course modifications and alterations had been in progress for some time before that date). That at least is the date given for Signal Instruction No.10 SED and is also the date given for the closure of Margate B in the SRS's signal box register, my version of which may be a bit out of date now but certainly that was the intended date.
Log in to reply |
Signal Time Out 08/12/2023 at 08:41 #154657 | |
kbarber
![]() 1723 posts |
Izzy in post 154642 said:It seems the world moves on as we get older - so some things have changed, thanks for the examples Geoff - especially that one at Basingstoke. I'm so glad i don't need to keep on top of it anymore since i retired.Thank you - and to TUT as well - for the dates for Margate. Mark Adlington https://www.wbsframe.mste.co.uk/public/index.htm gives 1952 for the commissioning of Clapham B, with East Croydon and South Croydon not commissioned until 1954 or '55, so only just preceding the Kent Coast scheme by the looks. I know who has the Battersea Park frame and he has a pretty encyclopaedic knowledge of working and interlocking of those frames; I must ask him what the situation was when it was in service there. Log in to reply |
Signal Time Out 08/12/2023 at 14:10 #154659 | |
flabberdacks
![]() 607 posts |
kbarber in post 154657 said:You're a gem Log in to reply |
Signal Time Out 10/12/2023 at 16:30 #154688 | |
kbarber
![]() 1723 posts |
kbarber in post 154657 said:Apparently approach locking that didn't time out was a Southern standard, both for power frames and for mechanical frames working colour light signals. My contact referenced an unofficial tool used to release the backlock at a certain (rather busy) mechanical frame, but otherwise the S&T needed to be called to release you. Apparently in later years a number of frames (including two power frames) were fitted with time-outs, but in each case the timer had to be initiated by pushing a button after returning the signal lever to the backlocked (B lock, for the technical) position. There were also a few boxes where an NX panel was installed alongside the L frame that acquired automatic timeouts when the panel was installed. Log in to reply |
Signal Time Out 10/12/2023 at 17:50 #154690 | |
Steamer
![]() 3958 posts |
kbarber in post 154688 said:Apparently in later years a number of frames (including two power frames) were fitted with time-outs, but in each case the timer had to be initiated by pushing a button after returning the signal lever to the backlocked (B lock, for the technical) position.What's the backlocked position? "Don't stress/ relax/ let life roll off your backs./ Except for death and paying taxes/ everything in life.../ is only for now." (Avenue Q) Log in to reply |
Signal Time Out 10/12/2023 at 22:47 #154696 | |
Sacro
![]() 1171 posts |
Steamer in post 154690 said:kbarber in post 154688 said:It means it's locked when putting the lever back in the frame, as opposed to locking it when pulling it out (I thinK!)Apparently in later years a number of frames (including two power frames) were fitted with time-outs, but in each case the timer had to be initiated by pushing a button after returning the signal lever to the backlocked (B lock, for the technical) position.What's the backlocked position? Log in to reply The following user said thank you: Steamer |
Signal Time Out 11/12/2023 at 01:25 #154697 | |
AndyG
![]() 1842 posts ![]() |
Steamer in post 154690 said:kbarber in post 154688 said:When replacing a signal lever (ie R to N), the backlock position (B in this case) is about 2/3 the way back, just past the centre on the normal side. This position places the signal to red (actually as soon as the lever moves from rev), but is locked from moving fully to the N if approach locking is in force until it times out, whereupon the lever can then be fully restored. In effect this holds the route locking to protect the train if it passes the signal while timing out.Apparently in later years a number of frames (including two power frames) were fitted with time-outs, but in each case the timer had to be initiated by pushing a button after returning the signal lever to the backlocked (B lock, for the technical) position.What's the backlocked position? {there is a series on 'notches' Norm-(X)-A-B-C-D-E-(Y)-Rev available in the quadrant, not necessarily used a lot of the time} kbarber in post 154688 said: Apparently approach locking that didn't time out was a Southern standard, both for power frames and for mechanical frames working colour light signals. My contact referenced an unofficial tool used to release the backlock at a certain (rather busy) mechanical frame, but otherwise the S&T needed to be called to release you. Apparently in later years a number of frames (including two power frames) were fitted with time-outs, but in each case the timer had to be initiated by pushing a button after returning the signal lever to the backlocked (B lock, for the technical) position. There were also a few boxes where an NX panel was installed alongside the L frame that acquired automatic timeouts when the panel was installed. The South Croydon frame (now Everglades at Gt Cockcrow Rly) definitely didn't times out as Neil Brady would confirm, as you say was Southern 'thing' to save a few coppers maybe? I can only help one person a day. Today's not your day. Tomorrow doesn't look too good either. Last edited: 11/12/2023 at 01:39 by AndyG Reason: None given Log in to reply The following users said thank you: Steamer, kbarber, flabberdacks |
Signal Time Out 11/12/2023 at 08:53 #154699 | |
kbarber
![]() 1723 posts |
AndyG in post 154697 said:Not too sure of the reasoning, to be honest. But we need to remember the original Southern Railway standard dates from the period when 'modern' signalling was under development so it may simply be that this novel safety feature was introduced and no-one thought that the signalman might need to escape from the locking as a matter of course. Log in to reply |
Signal Time Out 17/12/2023 at 23:34 #154764 | |
Coco-Banana-Man
![]() 18 posts |
Another question on the topic of approach locking / route timeouts... On Crewe simulation, I had the following situation: Signal WD161 on DF right before Acton Bridge (I put a reminder on it) has failed on Y/YY aspects (R/G still working). On the attached savegame, 4S44 is approaching. When setting the route from WD161 to WD163, WD161 gets unlit, therefore WD159 reverts to danger and 4S44 gets an ACOA. After that, when cancelling the route from WD161 to WD163 again, it gets cancelled immediately. Shouldn't there be approach locking in that case? Or is the fact, that WD159 had been reverted to danger, really enough for it not to be necessary? Stephan Post has attachments. Log in to view them. Last edited: 17/12/2023 at 23:34 by Coco-Banana-Man Reason: None given Log in to reply |
Signal Time Out 18/12/2023 at 05:07 #154767 | |
Hap
![]() 1016 posts |
Coco-Banana-Man in post 154764 said:Another question on the topic of approach locking / route timeouts...Firstly 4S44 is correcting in getting a ACOA as WD161 is not ina failed stated as the route is set to it. Once you have set the route over WD161 to WD163, WD161 goes into a failed state and reverts WD159 (THe last working protecting signal) to R. Defensive signalling would be required to avoid this situation happening. Either allow 4S44 and you will have to talk him passed the failed signal at it's most restrictive aspect (R), ensuring that any points ahead are secured, or you can divert via the Down Slow, or you can hold trains WD157 Until you are able to set up a full route to WD167, Where WD161 would either be showing R/G. WD161 wont have any approach locking in this instance because the route has not cleared initially. It is still in a restrictive state. IF it clearead to G then pulled, it has a 120s timeout. How to report an issue: www.SimSig.co.uk/Wiki/Show?page=usertrack:reportanissue Last edited: 18/12/2023 at 15:26 by Hap Reason: None given Log in to reply The following user said thank you: Coco-Banana-Man |
Signal Time Out 22/12/2023 at 11:38 #154797 | |
slatteryc
![]() 254 posts |
late contender for thread of the year , I've learnt more in this one thread than I thought was possible.
Log in to reply |