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| Level crossings route setting anomalies 25/12/2011 at 05:25 #26139 | |
maxand
1637 posts |
Why do some level crossings allow you to set a route when barriers are up, whereas others don't? For example, in Exeter sim, I can set routes across Silk Mill LC and Stoke Canon LC (whether AUT is on or off makes no difference), yet when I try doing the same at Pinhoe LC (EJ1-EJ5) and Crediton LC (CN1-CN5 ) it doesn't work and I see the message "Crossing not closed"? Doesn't make sense to me. Explanations appreciated. Thanks. Last edited: 25/12/2011 at 05:26 by maxand Log in to reply |
| Re: Level crossings route setting anomalies 25/12/2011 at 08:30 #26143 | |
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Sam Tugwell
494 posts |
Silk Mill Level Crossing is now a Bridge, so you can leave it lowered and cleared all day without any loss in the score. Paignton North LC requires the barriers to be down before a train leaves via PN4 and also PN6. This is simulated because thats actually what happens at the Panel itself. Sam "Signalman Exeter" Log in to reply |
| Re: Level crossings route setting anomalies 25/12/2011 at 09:20 #26145 | |
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Late Turn
699 posts |
Merry Christmas all! As Sam hints, there's all sorts of different locking around level crossings. In a mechanical box with a wheel- or hand-worked crossing, the protecting signals would be mechanically locked until the gate stop / gate lock / whatever lever is fully in the correct position following the operation of the gates - comparable to the position at Crediton, Paignton and Pinhoe. Although two of those three are not immediately adjacent to their controlling boxes, they're all worked from smallish panels rather than Exeter PSB itself (and different sorts of panel - OCS (???) as opposed to NX) - whether the nature of the locking makes any difference, I don't know, but I can imagine things being more complicated the 'Exeter PSB' way. Tom Log in to reply |
| Re: Level crossings route setting anomalies 25/12/2011 at 10:44 #26146 | |
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maxand
1637 posts |
Thanks to you both for your quick replies. I thought it was a case of "one rule fits all" but evidently not so. It appears to be a matter of getting to know each different type and its ways. Now I'm starting to understand Clive's reply a little more clearly: Quote: I have two sims that I wrote for myself and are never going to see the light of day. I'd send you a copy, but I think you'd find them incredibly boring. They're for testing out bugs and feature changes in the core code rather than for play as such. So one, for example, contains one circular track, five signals, no stations, and 58 automatic level crossings. Log in to reply |
| Re: Level crossings route setting anomalies 26/12/2011 at 09:38 #26185 | |
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Firefly
521 posts |
CCTV crossings will allow you to set the route prior to lowering the crossing Locally monitored crossings require the barriers to be down prior to setting a route. Simples Last edited: 26/12/2011 at 09:38 by Firefly Log in to reply |
| Re: Level crossings route setting anomalies 26/12/2011 at 10:17 #26188 | |
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Late Turn
699 posts |
But Pinhoe and Paignton are both CCTV crossings...? On the other hand, I know of at least one locally controlled crossing where the route can be set prior to lowering the barriers and the signal(s) come off as soon as 'crossing clear' is pressed (and isn't this how Horton Road works at Gloucester?). Are these just the inevitable exceptions to a general rule? Log in to reply |
| Re: Level crossings route setting anomalies 26/12/2011 at 10:28 #26190 | |
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maxand
1637 posts |
Firefly said Quote: CCTV crossings will allow you to set the route prior to lowering the crossing Are CCTV crossings identifiable in SimSig? As far as Exeter is concerned, the only crossings I could set a route for, prior to lowering, had AUT buttons, but that's for after the train passes, not before. In real life does a "CCTV crossing" mean the signalman can view the crossing on a screen? Or is it just for the man in the box? If you find time to expand on your earlier comments that would be appreciated. Last edited: 26/12/2011 at 10:28 by maxand Log in to reply |
| Re: Level crossings route setting anomalies 26/12/2011 at 10:59 #26191 | |
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Late Turn
699 posts |
Every full-barrier crossing must have some means of allowing the Signalman to ensure that the crossing is clear of obstructions before clearing the protecting signal - achieved either by looking out of the window or by providing CCTV (ignoring for simplicity the handful of 'remote control' level crossings which I'd understood can be up to 440yds from the box without CCTV, or the latest crossings with obstacle detection technology). On a real-life IECC, this means that most (all?) full-barrier crossings would be monitored by CCTV as they won't generally be located immediately adjacent to a crossing (and they're designed so that the Signalman can do everything from his workstation, without getting up to look out of a window!). In Simsig though, some simulations include areas signalled in reality by a smaller box (such as Crediton), where in reality the Signalman's crossing controls are located on a pedestal by the window, so that he can observe the crossing directly. There's more chance of these crossings lacking an auto-raise facility, as the Signalman can hardly miss a train passing right outside his window (and in many cases will need to observe its passage anyway to check for a tail lamp). Personally I find it frustrating having to keep an eye on a crossing just to raise the barriers behind the train, when the real thing would almost certainly auto-raise if it was controlled from the powerbox (where the Signalman will have a much higher workload) than from the adjacent box (where the Signalman's workload is much less, partly because each train requires so much attention). Tom Log in to reply The following user said thank you: maxand |
| Re: Level crossings route setting anomalies 26/12/2011 at 11:16 #26192 | |
guyh
54 posts |
Max, Cctv crossings are identified by the "clear" button; in real cctv crossings the signaller observes the cctv crossing on the screen and once the barriers are down asseses whether the crossing is clear - if so the signaller presses the button. Automatic half barrier crossings (AHBs) do not need cctv as there is always an escape route (only half the road width has a barrier). These also generally don't interlock with signals, they will just operate automatically when activated by a treadle on the track at the "strike in point". These are shown in SimSig (and of course in real life on a panel / iecc) as "raised / working / failed" and have no user intervention (although you should apply the correct rules if they do not behave properly but SimSig doesn't require) Log in to reply The following user said thank you: maxand |
| Re: Level crossings route setting anomalies 26/12/2011 at 11:48 #26194 | |
jc92
3685 posts |
" said:Max,which also applies to ones manually controlled without CCTV. to identify a crossing that is specifically CCTV on SimSig, as a general rule it will have autoraise (theres always exceptions to the rule!) some crossings in Simsig have been "CCTVed" compared to theyre real life counterparts. south humberside for instance has a number of crossings which are manual barriers or gates in real life and have been converted to CCTV because, in theory, thats what they would be if south humberside went over to IECC interface. Equally kiveton park LC on worksop is a CCTV even though its real life counterpart is not! "We don't stop camborne wednesdays" Log in to reply The following user said thank you: maxand |
| Re: Level crossings route setting anomalies 26/12/2011 at 12:18 #26195 | |
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Zoe
252 posts |
" said:which also applies to ones manually controlled without CCTV. I'm not sure that all MCB crossings have crossing clear buttons. Log in to reply |
| Re: Level crossings route setting anomalies 26/12/2011 at 13:47 #26197 | |
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maxand
1637 posts |
Great stuff, guys, it really makes the whole business a lot clearer now. Thanks a lot. (Added) Thanks Zoe for your post too. Had to look up MCB: Quote: In the UK, such crossings are categorised as 'Manually Controlled Barriers' (MCB) because they are always manually controlled, usually from a signal box. Some are known as MCB-CCTV level crossings, because they are supervised by video link to the signal box from which they are remotely controlled. (http://en.wikipedia.org/wiki/Four-quadrant_gate) Added it to Wiki Glossary. Quote: I'm not sure that all MCB crossings have crossing clear buttons. From where I'm located (Australia) I have no option but to play the sim, not the real location. :) But a bit of background always helps. I'll leave it to you real-life experts to argue the toss with the author of the sim as to how SimSig should handle it! Maybe the next upgrade will satisfy more users, but - I'm just happy to see that red stripe pass through that orange broken line. :laugh: PS no more Drambuie for me tonite. PPS More stuff to read when you've nothing better to do: http://en.wikipedia.org/wiki/Level_crossing http://en.wikipedia.org/wiki/Automatic_full_barriers Last edited: 26/12/2011 at 14:06 by maxand Log in to reply |
| Re: Level crossings route setting anomalies 26/12/2011 at 18:20 #26199 | |
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Firefly
521 posts |
Quote:But Pinhoe and Paignton are both CCTV crossings...? On the other hand, I know of at least one locally controlled crossing where the route can be set prior to lowering the barriers and the signal(s) come off as soon as 'crossing clear' is pressed (and isn't this how Horton Road works at Gloucester?).Ok not so simple, but that's the way it should be. Pinhoe does in reality have a crossing clear button and therefore you would in reality be able to set a route across it. The Evidence courtesy of Danny Scroggins:  Paigton has been simulated as a separate control area from a time when the box was still opened and all signals were prefixed PN. (Pre 1988) In reality it's now part of Exeter Panel and the crossing is now a CCTV so it should have crossing clear buttons and you should be able to set routes across the crossing prior to lowering the barriers. ( I suspect all signals now prefixed E) I can't comment on Gloucester, but you're correct it does go against my simplification. I suspect they cannot pre-set route at Gloucester or else they have a crossing clear button on the control pedestal. Quote: I'm not sure that all MCB crossings have crossing clear buttons.Correct they don't. Locally monitored CCTV crossings do not generally have crossing clear buttons and therefore you cannot set routes over them before they are fully down. The reason being that without a crossing clear button you wouldn't get a chance to verify the crossing was clear before the signal came OFF. (The signal would just come off immediately the barriers were lowered regardless if anyone was trapped.) The second problem is that you may get a signal flick R-G-R if you stopped the barriers just short of Down Detection (say 6 inches from the ground). This is because the barriers would bounce in and out of detection. Post has attachments. Log in to view them. Last edited: 26/12/2011 at 18:22 by Firefly Log in to reply |
| Re: Level crossings route setting anomalies 26/12/2011 at 18:36 #26200 | |
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Firefly
521 posts |
Also note from the photo that they have Auto-Raise at Pinhoe. Paington will no doubt have it too. Log in to reply |
| Re: Level crossings route setting anomalies 26/12/2011 at 19:07 #26201 | |
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kbarber
1742 posts |
I suspect this kind of variety is about when the LC installation dates from (arrangements will be dictated by then-current requirements and influenced by then-current fashions), the designer (I suspect every S&T engineer has his/her little foibles), the location (even with increasing standardisation the real-life railway is full of idiosyncracies, particularly where it interacts with the completely idiosyncratic (occasionally) semi-guided transport system called the road network), the particular interlocking design (generic circuits & ways of putting them together developed by the various contractors, the BR regions and eventually the BRB Chief S&TE Department) and imponderables such as what the operating department thought the signalmens' workload was likely to become on the day of the meeting where the S&T were given the design brief (and indeed whether the Chief Operating Manager & the Regional S&T Engineer got on, or who last brought who a pint). Yes, it can be a complete pain as you'll rarely (if ever) be able to be completely sure how a given installation will work. I guess this is one of the things that makes even modern signalling so endlessly fascinating. Believe me it's far less varied (therefore to me less interesting - YMMV) than manual signalling, where you have to learn every box as a completely new project (including how each individual lever pulls, so you can get them over as smartly as possible without doing yourself a mischief. No wonder I used to spend every minute I could get away with in a box somewhere.
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| Re: Level crossings route setting anomalies 26/12/2011 at 19:58 #26204 | |
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Late Turn
699 posts |
I'd definitely agree that any crossing with the facility to set the route prior to lowering the barriers needs a crossing clear button, for the reasons above. The reverse isn't necessarily true though - I've come across plenty of mechanical boxes with semaphore protecting signals and crossing clear buttons. I can only think that it's down to the age of the installation. Has Paignton box closed and control been transferred to Exeter? I honestly thought it still retained a small panel! Log in to reply |
| Re: Level crossings route setting anomalies 26/12/2011 at 20:07 #26205 | |
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Zoe
252 posts |
" said:I've come across plenty of mechanical boxes with semaphore protecting signals and crossing clear buttons. I can only think that it's down to the age of the installation. Have these had their barrier interlock levers removed? " said: I honestly thought it still retained a small panel! That is correct. Last edited: 26/12/2011 at 20:16 by Zoe Log in to reply |
| Re: Level crossings route setting anomalies 26/12/2011 at 20:22 #26206 | |
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clive
2789 posts |
Okay, rather than address points individually, here's a quick discussion about level crossings. There's three basic types of crossing: interlocked, automatic, and unsignalled. Interlocked crossings are interlocked with the signalling. They must completely block the roadway and be proved clear before a train can be signalled across them. Once the signals for a train have been cleared, it shouldn't be possible to open the road until the signals are returned to danger and proved clear of approach locking in some way. Interlocked crossings may use gates or barriers (and are then known as MG or MCB respectively). The crossing may be managed locally by a signaller at the crossing, managed remotely by a signaller that can see the crossing but isn't located at it (say just down the line), or managed via CCTV. The crossing is interlocked to the signalling in some way. With gates, one common approach is for a lever in the box to be pulled when the crossing is closed; this bolts the gates so they can't be opened until the lever is replaced. Standard interlocking then prevents the lever being replaced with the signals cleared. Or the crossing keeper locks the gates with Annett keys that are then removed and placed in a signalling lock of some kind. With barriers, the interlocking is usually electrical: the signals can't be cleared until the barriers are proven down and the "up" button is disabled when the signals are cleared. In some locations routes can't be set from the signals until the crossing is locked in one of these ways; in other locations, the routes can be set but the signals stay red until the crossing is locked. Crossings may also have auto-raise or auto-lower facilities. There's no specific rules for these; they're installed if the designer considered it the right thing to do. Now, barriers (or motorized gates) have a problem in that the signaller doesn't have to watch the crossing close and a car could be trapped. If a route can't be set until the crossing is closed, no extra protection is required. But if it can be, then the signal could clear with a car on the crossing. So in this case there has to be a separate stage to the process. This may consist of a slot on the signals, or it may consist of a separate "clear" button; in each case this has to be done by the signaller. SimSig allows all of the above combinations. In addition, it's possible to specific that there's no clear button but, instead, the crossing is "auto-clear" - it acts as if there's never a car trapped and a crossing keeper is pressing the clear button for you. What's put into a specific sim depends on the author. For example, in Cambridge there are two crossings with "clear" buttons. I put them there because I wanted to make things a bit harder, but left most of the other crossings without them to make it a bit easier to play single-handed. However, Elsenham and Foxton don't have "clear" buttons because they have local crossing keepers. If I did a refresh of Cambridge now, I'd make use of new features to allow the buttons to be included in hard modes and omitted in easy modes. [More in another message.] Log in to reply The following users said thank you: alan_s, maxand |
| Re: Level crossings route setting anomalies 26/12/2011 at 20:44 #26208 | |
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Late Turn
699 posts |
" said:
Clive's excellent summary has said more than I ever could, but to answer Zoe's question above - two local (to me) examples with photos available on the internet are Whissendine and Uttoxeter. From memory, the former has a crossing clear button and a barrier interlock lever; the latter has two crossings (one CCTV and one adjacent), both with crossing clear buttons and no barrier interlock levers (semaphore protecting signals, so you can't pull off until crossing clear has been pressed). Log in to reply |
| Re: Level crossings route setting anomalies 26/12/2011 at 20:52 #26213 | |
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Zoe
252 posts |
" said:
Considering you wouldn't be able to pull off the protecting signals unless the barriers have been locked down first, what is the purpose of the crossing clear button here? Last edited: 26/12/2011 at 20:52 by Zoe Log in to reply |
| Re: Level crossings route setting anomalies 26/12/2011 at 21:04 #26214 | |
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Sam Tugwell
494 posts |
Firefly Paignton is still a box. Known in the area as the "Broom Cupboard". "Signalman Exeter" Log in to reply |
| Re: Level crossings route setting anomalies 26/12/2011 at 21:40 #26217 | |
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GoodbyeMrFish
148 posts |
" said:Automatic half barrier crossings (AHBs) do not need cctv as there is always an escape route (only half the road width has a barrier). These also generally don't interlock with signals, they will just operate automatically when activated by a treadle on the track at the "strike in point". These are shown in SimSig (and of course in real life on a panel / iecc) as "raised / working / failed" and have no user intervention (although you should apply the correct rules if they do not behave properly but SimSig doesn't require)Kiln lane is another example of this (cambridge sim), i film there often and if your crossing sometimes you can actually see the train coming towards you before the yodels start to sound. Doable because of the line speed there is quite low. another interesting thing is if a second train is coming the sound of the yodels speed up. shamefull plug i know but heres a clip i filmed a few years ago of 2 freight trains crossing here. [video width=425 height=344 type=youtube]FSIs7LOapxM[/video] Last edited: 26/12/2011 at 21:41 by GoodbyeMrFish Reason: added video twice :( Log in to reply The following user said thank you: maxand |
| Re: Level crossings route setting anomalies 27/12/2011 at 07:51 #26227 | |
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clive
2789 posts |
Automatic crossings aren't interlocked with the signalling but operate automatically on the approach of a train. There are four kinds: the crossing can have half-barriers that block the road entrance to the crossing but leave the exit clear (AHB and ABCL) or have no barriers at all (AOCL and AOCR), and they can be monitored by a signal box (AHB and AOCR) or by the train driver (ABCL and AOCL). In the former case, there will be "RAI", "LWR", and "FAI" lamps on the panel and, if there's a problem, the signaller must put protecting signals back to danger. In the latter case, the train driver needs to be prepared to stop at the crossing; a flashing white light will indicate that the crossing is working correctly. SimSig simulates these types. Unsignalled crossings come in a range of types, such as occupation, trainman operated, open, and user operated. Some have miniature red and green warning lights for road/footpath users, and some have telephones. SimSig can simulate these. Log in to reply |
| Re: Level crossings route setting anomalies 27/12/2011 at 08:16 #26228 | |
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Firefly
521 posts |
Quote:Paignton is still a box. Known in the area as the "Broom Cupboard".Yes, my mistake. I saw that Paignton South was de-commissioned in 1989 and assumed it had gone onto Exeter. However I note the Paignton Level Crossing is a CCTV level crossing, therefore assume it has crossing clear and Auto Raise buttons. FF Log in to reply |