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How does interlocking know its own arrangement? 09/03/2014 at 13:15 #56770 | |
DaveBarraza
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" said:You can add NYCTA to that list! There will be a Westrace installed there in a could of years, programmed from "scratch." Before they were bought by Invensys, SafeTran had a tool called the "Geo" which was intended to be a drag-and-drop interlocking tool. One difficulty with that was the varying approaches between the major US railroads - every engineering group wanted their own "objects" developed whether or not one already existed for their competitor which was 95% the same. " said: SSI, and thus Smartlock and Westlock which are generally compatible variations, are heavily designed for UK main line requirements. That's what it was designed for, and it does it very well (but like all processor-based systems, slower than relays). It's good enough to be used elsewhere in the world too - Belgium and Spain come to mind for starters.Standards in the UK seem very well defined. I can see how specialized platforms could work very well. " said: The safety assessors and suchlike prefer more automation to reduce mistakes. I think it depends on the automation though, as to how likely one is to make mistakes.Most automation makes huge errors that are easy to spot. The scary prospect is a highly contextual problem that doesn't easily reveal itself. And to me there is a long term problem with automation, which is that eventually there will be no one to check it. One normal progression "up the ranks" might be: Detailer > Block Signals Designer > Interlocking Designer > Circuit(or SSI Logic) Checker > Author of Testing procedures. In the end commissioning testing by experienced engineers is intended to catch any errors which have made it through the design process. If the easier parts of the design process are automated then after a while there will not be any experienced senior engineers. -And for the Prover iLock contingent: Yes, you can put all of your safety rules into a computer and have it check the safety of an interlocking... assuming there are engineers who know the subtleties of the rules (see above!) " said: This I find odd as probably 75% of US interlockings follow one of two patterns - pairs of universal crossovers, or single-to-double track! If anything could gain from automation and/or ready-made units, this would be it! Yet it appears that the designs are written over and over again. No doubt there is a lot of replication (risking copying errors), especially with stuff like Microlok boolean/ladder logic.It's quite possible that since I'm in a part of the US with a very dense rail infrastructure, I have a skewed perspective! I do hear from the "freight" people at my company that their job is a lot of crossing-crossing-crossing, siding-siding-siding, ad nausea. They can and do use a (digital!) rubber stamp. Tying it back to the start of the thread, for such simple plants there is no real "arrangement" that the interlocking like that needs to "know". I don't think the re-used logic for an End of Siding hut could be readily placed into the context of a larger interlocking. Log in to reply |
How does interlocking know its own arrangement? 10/03/2014 at 02:48 #56782 | |
maxand
![]() 1637 posts |
This may or may not be relevant, but long before I began playing SimSig I used to play Train Dispatcher, an American game, where it was possible to stack up to five routes across a junction in memory, so that after Train A passed through and completed its route, a new route was automatically set for Train B (passing the opposite way) and maybe even for Train C (same direction as Train A). This may not have been realistic, but by heck it was fun! The game has not been updated since 2006, but is still available. From the manual (2000): Quote: 6.2.5. Stack Route CommandsSince this thread has had a lot of feedback from American forum members, I would be interested to know whether route stacking is actually used in American signalling, and how common this is. Surely interlocking software ought to be sophisticated enough to cope with this helpful feature. If enough people consider this matter off-topic, I will be happy to create a new one for it. Last edited: 10/03/2014 at 02:49 by maxand Log in to reply |
How does interlocking know its own arrangement? 10/03/2014 at 10:19 #56788 | |
kbarber
![]() 1723 posts |
" said:This may or may not be relevant, but long before I began playing SimSig I used to play Train Dispatcher, an American game, where it was possible to stack up to five routes across a junction in memory, so that after Train A passed through and completed its route, a new route was automatically set for Train B (passing the opposite way) and maybe even for Train C (same direction as Train A). This may not have been realistic, but by heck it was fun! The game has not been updated since 2006, but is still available. In UK practice, presetting (I have heard it called 'oversetting' ![]() There are/were some exceptions (and some you might not call exceptions). You can generally set a second route while part of it is still occupied by a preceding train, so long as any points required to be moved are clear. I'm not sure whether anyone would call this 'presetting'; it certainly doesn't meet the description of 'stacked routes' but it does allow a degree of setting ahead of time. The ultimate in this is where signalling is worked from a lever frame (miniature or full-size levers, I've seen it on both) and there are endless successive moves; the result is that every time a train passes the signal(s) the signalman simply 'restrokes' the lever - puts it back then pulls it straight back over again. On the 1957 OCS panel at St Pancras I believe it was possible to overset one conflicting route, but no more. The second route wouldn't set until both all points in the route were clear and the switch for the first route had been returned to normal. You needed to be fairly sure of yourself doing this; the points were all electro-pneumatic and went very fast - you didn't even have time to blink between route setting initiating and the signal clearing. London Transport panels also allow presetting of a single conflicting route. I've seen it done at Barking, to be sure - in fact there's even an indication for it. Perhaps I should say that those LT panels - mainly dating from the early 1960s, before the advent of programme machines - are a special kind of OCS panel. They use illuminated perspex pushbuttons (like a large button on an NX panel) rather than switches and they don't operate relay interlockings, but rather use pneumatic cylinders to drive remote 'lever frames'. The frames were set up so that signal levers returned to normal after the passage of a train so functionally, as far as the operator was concerned, they had a form of TORR. The earliest panels had just one colour of illumination, a sort of orange-red, and the button was illuminated when a route was set or dark otherwise. This was the type installed at Farringdon, which I saw once at the end of the 1970s. A few years on, they had progressed to three colours: with no route set the button was illuminated red; with a route cleared it was green; when a button was selected but the route didn't clear (either because of approach releasing for a junction, because of a preceding train still in the section, or because it was presetting over a conflicting route) a yellow indication was given. (The remote lever frames may be conventional, but in many cases they are the London Transport/Westinghouse 'Style V', which uses vertical shafts with small handles rather than conventional levers - they are, effectively, the rotating shafts of a 'L' or 'N' frame separated off and used without the paraphernalia of levers.) I believe Kings Cross, when commissioned, allowed stacking of up to six routes in the KX station area. (I think I read it in a Modern Railways article; given we're heading for 40 years ago I rather hope my grey cell is in reasonable order!) In those days, of course, there was full loco working of all trains rather than the present push-pull or unit train working, and there was also the old loco servicing point ('Bottom Shed' ![]() Log in to reply The following user said thank you: maxand |
How does interlocking know its own arrangement? 10/03/2014 at 10:26 #56790 | |
maxand
![]() 1637 posts |
All I can say is - wow! Thanks again Keith for your marvellous erudition. Would love to hear from you guys across the pond. Log in to reply |
How does interlocking know its own arrangement? 10/03/2014 at 10:54 #56793 | |
DaveBarraza
![]() 88 posts |
I was walked through Penn Station Central Control and it looked like they used a flashing route for stacking...
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How does interlocking know its own arrangement? 10/03/2014 at 14:44 #56801 | |
kbarber
![]() 1723 posts |
" said:All I can say is - wow! Thanks again Keith for your marvellous erudition. I like posts like that! B) Thank you Max. Not that I'm sure I'd call it erudition... more a sign of a misspent youth (no wine, women & song for me... just a nice busy signalbox) and a brain that rarely lets anything be thrown away ![]() Log in to reply |
How does interlocking know its own arrangement? 10/03/2014 at 17:09 #56806 | |
GeoffM
![]() 6344 posts ![]() |
" said:In UK practice, presetting (I have heard it called 'oversetting'I believe the "official" term is anti-preselection and it's frowned upon because the signaller is not supervising the action when it eventually takes place. Auto working doesn't fall under this category because the route doesn't free and then set again - it remains set. Automatic Routesetting (ARS) gets away with it because it is supervised by the machine. (Mind you, if ARS can get away with it, why not let a machine supervise preselection?) I've always heard "oversetting" used to refer to setting the same route over the remains of the existing one, or possibly a different route but ending in the same signal. Presetting, again TTBOMK, that refers to a route from one main signal to the next presetting a shunt signal (or more than one) in between. That's not to argue with anything you've said. As we all know, the railway is full of inconsistencies! As for "where in the world" stacking takes place, it certainly does happen in the US. Depending on the interlocking it can happen on one of two levels - either the control system sends a request to the interlocking and it either actions it or stores it for setting when available; or, the control system stacks internally and sends the request when it thinks it'll be accepted by the interlocking. Incidentally "fleeting" (auto working) is achieved either by the interlocking, or the control system requesting the same route again once a train passes. The other place I've seen it is in Oslo, Norway. In a complex station like Oslo Central Station the interlocking actually reserves the objects as they become available. That is, with a conflicting move taking place, once a track becomes clear or a point free to move, it'll get reserved/locked for the stacked route. I had great fun trying to program that for their simulator, I can tell you! :woohoo: In both cases above I've seen green triangles by the entrance signal and red by the exit signal to indicate a stored/stacked route. Can't remember if they were steady or flashing. Sequential stored routes would have a green arrow at the intermediate signals so you'd see green-green-red (triangles) for two consecutive routes. SimSig Boss Log in to reply The following users said thank you: maxand, DaveBarraza |
How does interlocking know its own arrangement? 10/03/2014 at 21:03 #56815 | |
Forest Pines
![]() 525 posts |
The Oslo example does sound potentially risky in that - at least in theoretical terms - surely there's a risk of the interlocking getting into a deadlocked state, if two conflicting routes have both been stacked and are partially locked and contending for the same objects. Presumably there is some sort of deadlock avoidance built in, for example by ensuring that two routes will always contend for objects in a consistent order.
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How does interlocking know its own arrangement? 10/03/2014 at 21:18 #56816 | |
GeoffM
![]() 6344 posts ![]() |
" said:The Oslo example does sound potentially risky in that - at least in theoretical terms - surely there's a risk of the interlocking getting into a deadlocked state, if two conflicting routes have both been stacked and are partially locked and contending for the same objects. Presumably there is some sort of deadlock avoidance built in, for example by ensuring that two routes will always contend for objects in a consistent order.Now you've got me! It wouldn't be unsafe but could be undesirable certainly. It's been nearly 3 years since I last worked on it so I can't remember the specifics, but I would imagine the request could be cancelled even if partially reserved. SimSig Boss Log in to reply |
How does interlocking know its own arrangement? 11/03/2014 at 09:58 #56823 | |
Harsig
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" said:Just to add to this there was a fourth possible indication with this version of the system and this was no illumination in the button. This meant the route had not been selected but the signal was not at danger. This situation was most commonly seen where a signal had multiple routes. When one route was cleared the associated route button shows green and the red indication in all the other route buttons associated with that signal are extinguished. A fifth indication exists where these route buttons control multiple aspect signals, i.e. at Rickmansworth and Amersham. In this case a flashing yellow indication is provided in the button when the signal is showing a proceed aspect other than green. The button turns green only when the associated multiple aspect signal shows green on the ground. Last edited: 11/03/2014 at 09:59 by Harsig Log in to reply The following user said thank you: kbarber |
How does interlocking know its own arrangement? 11/03/2014 at 10:23 #56824 | |
kbarber
![]() 1723 posts |
" said:" said:In UK practice, presetting (I have heard it called 'oversetting'I believe the "official" term is anti-preselection <snip> I think this is a prime example of things that have a very specific meaning to the 'Sleep & Tea' being spoken of more loosely by the people that work them. Goes on all over the railway. I don't know how it works Guv, I just pull the levers! Log in to reply |
How does interlocking know its own arrangement? 11/03/2014 at 17:43 #56829 | |
Firefly
![]() 521 posts |
I'm used to being referred to as Sick and Tired or Sugar and Tea. Sleep and Tea is a new one on me ![]() I agree with Geoff's terms. When setting a route over the top of another route we call it oversetting. Another funny term that was used when testing Western Region interlockings is "pumping stick" This meant re-stroking a route which had returned to red following the passage of a train. (re-picking the stick control) Log in to reply |
How does interlocking know its own arrangement? 12/03/2014 at 09:38 #56850 | |
kbarber
![]() 1723 posts |
" said:
That's what I'd have called restroking, whether of a route or of a lever. Yes, we do have some interesting slang and jargon don't we? Log in to reply |