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Tower 18 Routesetting 31/12/2014 at 02:10 #67210 | |
kaiwhara
587 posts |
Heya Having a play with this sim, absolutely love it. Great curve ball that really threw us all off the scent! Hey, quick question about route setting though. When setting a route from X118 to LP2_153, ie from Clinton to Clark/Lake, and the platform at Clark/Lane is occupied from right to left, a train from Clinton will stop just short of the last controllable trailing points (P7 according to F11). However a train signalled from X112 to LP2_153 allows a train to pull a lot closer to the rear of the train ahead, virtually right up the tail lights of it! Is this right? I know that we got told not to take this simulation too seriously (and I don't think I am), but it almost seems like trains from Clinton should be able to draw a bit further ahead, in view of how trains behave around Tower 12 and other routes around Tower 18. This is particularly noticeable about 8am on the new timetable. Cheers! Sorry guys, I am in the business of making people wait! Last edited: 31/12/2014 at 02:12 by kaiwhara Log in to reply The following user said thank you: guidomcc |
Tower 18 Routesetting 31/12/2014 at 02:24 #67212 | |
Muzer
718 posts |
Yeah, I was actually just about to post a thread about this! I would hazard a guess that it's a bug, albeit one that makes things a lot more "interesting" ;).
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Tower 18 Routesetting 31/12/2014 at 02:58 #67213 | |
GeoffM
6344 posts |
It was mentioned before but today is the first I've had a chance to look at it. Yes, it was a bug relating to approaching from Clinton. What seems to happen in real life when there is a train at Clark/Lake is that the following train will get slowed approaching "LP2 153" (the board immediately between the manual scissors and the 3-way junction) but will then accelerate and approach "LP2 151" at a low speed. Again, I don't know for sure, but I suspect it's some kind of control that broadly equates to "overlap track clear or berth occupied occupied for time". Whether there really are overlaps is questionable. The fault was because the track length from the Clinton direction was too short so the train was stopping a "safe" distance from the signal, but failing to operate the kind of approach control. Chicken and egg! Fixed now, expect an update in the next few days. SimSig Boss Last edited: 31/12/2014 at 03:01 by GeoffM Log in to reply |
Tower 18 Routesetting 31/12/2014 at 03:07 #67214 | |
kaiwhara
587 posts |
Thanks Geoff In the meantime, will continue enjoying tying myself into the tightest knots imaginable! :whistle: Sorry guys, I am in the business of making people wait! Log in to reply |
Tower 18 Routesetting 31/12/2014 at 03:34 #67216 | |
Muzer
718 posts |
After hearing GeoffM's explanation, I came up with the idea (as a temporary fix until this new version is out) of using "shunt forward" to get the train to move towards the signal and so trigger the approach control. This works, though obviously having to go to the train list every time it happens is far from ideal, it does at least mean there's a way to clear the junction more quickly when this happens! Incidentally, in real life, how likely are the trains to stick to the timetables? For example, if they happened to arrive on the loop two minutes early, would they just hang around at the first station, or would they keep dwell time down to a minimum? I'm inclined to expect the latter, in which case perhaps timetables should use the "set down only" option or similar to enforce this? I don't know. Last edited: 31/12/2014 at 03:35 by Muzer Log in to reply |
Tower 18 Routesetting 31/12/2014 at 04:26 #67220 | |
GeoffM
6344 posts |
" said:Incidentally, in real life, how likely are the trains to stick to the timetables? For example, if they happened to arrive on the loop two minutes early, would they just hang around at the first station, or would they keep dwell time down to a minimum? I'm inclined to expect the latter, in which case perhaps timetables should use the "set down only" option or similar to enforce this? I don't know.I would imagine the latter - to clear the loop. Once out of the loop the intervals are much greater of course. I know that, like London Underground, CTA dispatchers can hold trains verbally (or by signals) to even out the interval. There was an incident report I found while researching the area of somebody impersonating CTA officials by using a two-way radio to issue "instructions". On that report they mentioned holding trains back for regulation purposes, amongst other things. SimSig Boss Log in to reply |
Tower 18 Routesetting 31/12/2014 at 13:29 #67246 | |
Muzer
718 posts |
" said:" said:Whoa, do you have a link to that? I'd love to read that report!Incidentally, in real life, how likely are the trains to stick to the timetables? For example, if they happened to arrive on the loop two minutes early, would they just hang around at the first station, or would they keep dwell time down to a minimum? I'm inclined to expect the latter, in which case perhaps timetables should use the "set down only" option or similar to enforce this? I don't know.I would imagine the latter - to clear the loop. Once out of the loop the intervals are much greater of course. I know that, like London Underground, CTA dispatchers can hold trains verbally (or by signals) to even out the interval. There was an incident report I found while researching the area of somebody impersonating CTA officials by using a two-way radio to issue "instructions". On that report they mentioned holding trains back for regulation purposes, amongst other things. Log in to reply |
Tower 18 Routesetting 07/01/2015 at 13:38 #67479 | |
Jersey_Mike
250 posts |
" said:It was mentioned before but today is the first I've had a chance to look at it. Yes, it was a bug relating to approaching from Clinton. What seems to happen in real life when there is a train at Clark/Lake is that the following train will get slowed approaching "LP2 153" (the board immediately between the manual scissors and the 3-way junction) but will then accelerate and approach "LP2 151" at a low speed. Again, I don't know for sure, but I suspect it's some kind of control that broadly equates to "overlap track clear or berth occupied occupied for time". Whether there really are overlaps is questionable.With the short block spacing in the Tower 18 area it might be that timers are used on some of the signals (either wayside or cab). The CTA is an odd duck that makes full use of cab signals with automatic train control, but also retains wayside automatic signals in the loop area and still relies somewhat on mechanical automatic train stop. Cab signal codes can take a few seconds to register which requires larger train spacing to ensure sufficient stopping distance. A popular method to tighten things up on many similar systems is to stop a train short of the signal then turn on a low speed cab signal code to allow the train to creep up. On most systems this process is manual because it is rarely needed, but the CTA appears to have hooked it into a typical transit style timer to automatically clear the outer signals to close in on the junction. BTW, I am having trouble locating the LP2 153 automatic in relation to the LP2 151 automatic. Green Line trains approaching Tower 18 from Clinton do not pass any autos before LP2 153. Also, I am not sure the NX panels would be set up to line routes between a controlled signals (prefixed with X) and an automatic signal (one of the LPs). Anyway,here's a video I took from the front of a Brown Line train when construction closed down half the loop and Brown Line service was running through as Orange Line service. Might be something you could implement as an alternate service pattern. In this case I did not notice any "timer" effect in advance of the X102 signal at the Tower 18 crossing. https://www.youtube.com/watch?v=GuVM6snKKP8 Last edited: 07/01/2015 at 13:42 by Jersey_Mike Log in to reply |
Tower 18 Routesetting 07/01/2015 at 16:18 #67485 | |
GeoffM
6344 posts |
" said:The CTA is an odd duck that makes full use of cab signals with automatic train control, but also retains wayside automatic signals in the loop area and still relies somewhat on mechanical automatic train stop.There are a couple of colour light signals not related to pointwork which aren't shown in the sim. I'm not sure what their purpose is. " said: BTW, I am having trouble locating the LP2 153 automatic in relation to the LP2 151 automatic. Green Line trains approaching Tower 18 from Clinton do not pass any autos before LP2 153. Also, I am not sure the NX panels would be set up to line routes between a controlled signals (prefixed with X) and an automatic signal (one of the LPs)."LP2 153" should actually be "LP2 154" (thanks to the hidef videos released while I was developing this) and can be seen here. Where would you route to on an NX panel if not an exit "signal" or notional exit point? Cheers. SimSig Boss Log in to reply |
Tower 18 Routesetting 07/01/2015 at 17:26 #67488 | |
Jersey_Mike
250 posts |
" said:Those are automatic block signals that are seen at various points around the loop and in the downtown subways. I suspect they exist as a method to enable higher levels of traffic density where cab signals require too much space. Consider the LP1 151 automatic. There is only one train length between it and Tower 18's home signal. Under pure cabs a train approaching from behind would likely be stopped partway down the platform at Clark/Lake due to signal overlap in case the cab code takes longer to register. With a wayside signal the train can proceed right up to the first because the operator not only has a visual indication of a stop point, but also there's an mechanical ATS trip to protect the leading train. The mechanical trip triggers the emergency braking rate while the cab signal triggers a full service braking rate further reducing the overlap distance to practically nothing. If you remember this incident, each of the stub tracks at O'hare have been filled with lines with automatic signals on timers with trip stops. " said: " said:The only LP signal Pink and Green lines pass near Tower 18 is LP2 151 at 24:57. (In my first post I should have typed "Green Line trains approaching Tower 18 from Clinton do not pass any autos before LP2 151" This automatic allows a following train to clear the Tower 18 crossing even with another train in the station.BTW, I am having trouble locating the LP2 153 automatic in relation to the LP2 151 automatic. Green Line trains approaching Tower 18 from Clinton do not pass any autos before LP2 153. Also, I am not sure the NX panels would be set up to line routes between a controlled signals (prefixed with X) and an automatic signal (one of the LPs)."LP2 153" should actually be "LP2 154" (thanks to the hidef videos released while I was developing this) and can be seen here. " said: You would run it to signal governing opposing movements into the interlocking. North American interlockings have well defined limits compared to UK interlockings, which are rather losey goosey. You pass a signal with an X and you have entered and interlocking. At some point you pass a signal with an X facing the other direction on your track and you have exited the interlocking. Often times different rules apply depending on if you are in an interlocking or not. The CTA makes things even more explicit by putting all sorts of signs next to signals that admit trains to interlockings. In this photo you can see Tower 18's #108 and #106 signals in advance of the LP1 151 automatic. LP1 151 does not have a control on the operator's board and is not used as an entry or exit point. 108 and 106 are exit points for trains heading the opposite direction. BTW I have a number of Tower 18 interlocking photos here. Just scroll down to files beginning with CTA_TOWER-18. Log in to reply |
Tower 18 Routesetting 07/01/2015 at 18:55 #67492 | |
GeoffM
6344 posts |
" said:" said:Not really: I don't recall the location of them all without watching again, and there are only something like 2-4 for the entire loop area. I do recall one anti-clockwise/LP1/outer leaving Randolph/Wabash immediately before the curve. There is still a yellow LP1 plate (133 I think). My first thought was visibility around the curve but then there are cab signals so why would that be needed. Spacing isn't an issue there - you want to space signals closer (or blocks shorter) closer to the pinch points - in this case Tower 18 for example.Those are automatic block signals that are seen at various points around the loop and in the downtown subways. I suspect they exist as a method to enable higher levels of traffic density where cab signals require too much space. Consider the LP1 151 automatic. There is only one train length between it and Tower 18's home signal. Under pure cabs a train approaching from behind would likely be stopped partway down the platform at Clark/Lake due to signal overlap in case the cab code takes longer to register. " said: If you remember this incident, each of the stub tracks at O'hare have been filled with lines with automatic signals on timers with trip stops.That's called Moorgate Control in the UK, installed over 30 years ago, after a fatal crash at Moorgate. " said: The only LP signal Pink and Green lines pass near Tower 18 is LP2 151 at 24:57.Did you see the video I posted? " said: " said:Okay, that makes sense. There are a small number of cases like that in the UK - well, more so on NX panels rather than NX VDUs, though there are some.Where would you route to on an NX panel if not an exit "signal" or notional exit point?You would run it to signal governing opposing movements into the interlocking. " said: North American interlockings have well defined limits compared to UK interlockings, which are rather losey goosey.You have to understand the difference between a North American interlocking and a UK interlocking. Of course a UK interlocking has very strictly defined limits and these are marked on scheme drawings and signaller panels. But drivers in the UK have no need to know where an interlocking boundary is as there are no rules specific to such for drivers. Engineers in the US/CA do have specific rules governing interlockings, hence the need to make it easy to know when you're entering an interlocking and exiting same. On the same basis, UK interlockings cover a wide or complex area (rarely both!); the most common NA interlocking is probably that of three signals, a switch, an "OS" track, and three approach "tracks" (which are more likely combinations of several approach tracks). Two very different meanings. " said: BTW I have a number of Tower 18 interlocking photos here. Just scroll down to files beginning with CTA_TOWER-18.Thanks - was hoping for close ups of the panel but the video linked to in the manual is about as close as I've seen. SimSig Boss Log in to reply |
Tower 18 Routesetting 07/01/2015 at 18:58 #67493 | |
Muzer
718 posts |
Yeah, I'd also love pictures of the panel.
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Tower 18 Routesetting 07/01/2015 at 20:11 #67498 | |
Jersey_Mike
250 posts |
" said:The other reason they can be used is for separation purposes. It is preferable to hold a train at a station than departing and getting stuck on signals 10 feet off the platform. One last use would be cab signal failure, but I'm willing to bet there are absolute block procedures in that case. " said: I followed the link and that was the only LP2 signal I could identify. Am I just missing something? " said: Here is an example NX panel from a simpler crossover interlocking showing the placement of the push-pegs. https://www.acm.jhu.edu//~sthurmovik/Railpics/14-06-21_TOWER_B-12/CTA_DAMEN-panel-right.html And the actual interlocking. https://www.acm.jhu.edu//~sthurmovik/Railpics/14-06-21_TOWER_B-12/CTA_DAMEN-272sig+274sig+int-eb.html There is an auto for trains approaching the station and I am betting its to allow trains to get closer to eachother because mechanical trips allow shorter/no overlap, but the CTA will only attach a mechanical trip stop to a wayside signal. Emergency stops can cause passenger injuries so they would really want to avoid having too many of those. " said: I do not believe that UK interlockings require signals at every entry-exit point, something that most NA interlockings do. " said: Area interlockings were more common (PU tower in Phillipsburg, NJ apparently had limits 5 miles long and CORK tower in Lancaster, PA was 3-4 miles long), but recently railroads have been chopping them up in smaller logical chunks to reduce the re-testing burden if changes need to be made. Regarding Tower 18, only the crossing and related signals are part of TOWER 18 interlocking. Each of the movable bridges are considered separate even if they are run from the same panel and use the same numbering sequence. When a single interlocking presents multiple controlled signals to a train it can make giving verbal instructions more complicated. The Long Island Rail Road is the only one that continues to use area interlockings, and even then it has had to affix ID plates to its signals to make verbal instructions clear. " said: Sorry, I don't have many contacts at the CTA. At least the signals are all properly identified. In normal NA practice only automatics have IDs. To get the real numbers you either have to look for chalk markings or get the interlocking sheets. Log in to reply |
Tower 18 Routesetting 07/01/2015 at 21:28 #67500 | |
GeoffM
6344 posts |
" said:" said:I followed the link and that was the only LP2 signal I could identify. Am I just missing something? [/quote]The only LP signal Pink and Green lines pass near Tower 18 is LP2 151 at 24:57.Did you see the video I posted? Using the Pink line southbound this is the sequence of signals/block markers you pass: X116 (protecting the diamonds) [cross the diamonds] LP2 154 (back-to-back with X108) Scissors crossover LP2 151 Start of Clark/Lake platform LP2 150 End of Clark/Lake platform " said: I do not believe that UK interlockings require signals at every entry-exit point, something that most NA interlockings do.Correct - because there is no notion for a UK driver to be in a particular interlocking. You can pass through an interlocking without passing a single signal, and conversely can pass a score of signals in the same interlocking. It all depends. " said: but recently railroads have been chopping them up in smaller logical chunks to reduce the re-testing burden if changes need to be made.Which is the opposite to the UK. SSI, an electronic interlocking, has been the interlocking of choice since the 90s but is a fixed size. Two companies, Westinghouse Signals (now Siemens) and another company whose name escapes me at the moment, both developed successors to SSI but which are largely compatible. The Westinghouse one went the way of 3-4x the size (but has since been limited to 2-2.5x as it hasn't performed as well as expected) called Westlock, but Smartlock kept the same interlocking size but made it easier to communicate between the interlockings. Communication between interlockings in complicated areas massively expanded the testing time and data complexity so reducing those boundaries by increasing the size, or making them easier to navigate, made for simpler testing. But, again, it's not like we're comparing apples and apples here. The US doesn't have many stations that would not fit into a single SSI - New York Penn, Grand Central, Newark NJ, Chicago Union (to a degree - it's logically quite a simple layout despite looking large), and Los Angeles UPT are the only ones that come to mind. Hoboken and Jamaica possibly. SimSig Boss Log in to reply |
Tower 18 Routesetting 07/01/2015 at 23:01 #67505 | |
Jersey_Mike
250 posts |
" said:Oh, I see. It's not one with a wayside signal attached to it. " said: That is such a strange system to have developed. Probably something to do with your reliance on manual block. Under old North American manual block rules you would sometimes have ABS block stations with crossovers and semi-automatic signals in the "correct" direction of travel only. Trains running reverse would stop before fouling the crossovers. " said: All of our interlockings can be sold or transfered to different railroads. Also I have never known a situation where the vital logic wasn't in the field adjacent to the track. True area interlocking is almost unheard of. Log in to reply |
Tower 18 Routesetting 07/01/2015 at 23:19 #67508 | |
Steamer
3958 posts |
" said:" said:Take a look at the Edinburgh Signal Number Plan to see typical interlocking sizes in the UK. For some reason, each interlocking has a different signal prefix* (this appears to be a feature of big Scottish boxes, it's rare in England and Wales) denoting the interlocking it belongs to. All signals are controlled by Edinburgh box. I don't know if drivers are aware of the significance of the prefixes- it won't change how they interpret the signal. They only need to know which signal box controls the line they're currently on.That is such a strange system to have developed. Probably something to do with your reliance on manual block. Under old North American manual block rules you would sometimes have ABS block stations with crossovers and semi-automatic signals in the "correct" direction of travel only. Trains running reverse would stop before fouling the crossovers. "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 |
Tower 18 Routesetting 07/01/2015 at 23:41 #67510 | |
Ron_J
330 posts |
" said:That is such a strange system to have developed. Probably something to do with your reliance on manual block. Under old North American manual block rules you would sometimes have ABS block stations with crossovers and semi-automatic signals in the "correct" direction of travel only. Trains running reverse would stop before fouling the crossovers. It's not strange at all, it's just different from what you're used to. Personally I find almost every aspect of US railroad operation completely baffling. Log in to reply |
Tower 18 Routesetting 08/01/2015 at 00:15 #67513 | |
GeoffM
6344 posts |
" said:Oh, I see. It's not one with a wayside signal attached to it.Well no, precious few of them do! " said: " said:It's certainly not strange to us, and also nothing to do with manual block - in fact, manual block would be closer to the US definition of an interlocking. Mind you... define "manual block" as there is a possibility you're talking about something else.That is such a strange system to have developed. Probably something to do with your reliance on manual block. Under old North American manual block rules you would sometimes have ABS block stations with crossovers and semi-automatic signals in the "correct" direction of travel only. Trains running reverse would stop before fouling the crossovers. " said: All of our interlockings can be sold or transfered to different railroads. Also I have never known a situation where the vital logic wasn't in the field adjacent to the track. True area interlocking is almost unheard of.They used to be (remote relay rooms) but with electronic interlockings there is no need. Indeed, surely it would be better to have the interlocking close at hand in case it needs a bit of TLC instead of driving 50 miles or more? Another difference: the link between signallers and their signals, tracks, and points is safety critical (vital) in the UK; in the US many such controls and indications are sent over the airwaves, and AIUI indications cannot be relied upon. (A couple of months ago I used a hand held scanner to "listen" to the over-the-air transmissions while on a train between Seattle and Chicago. While it couldn't see far in front, there was usually enough signal to determine when we would pass another train. Fun and legal) SimSig Boss Log in to reply |
Tower 18 Routesetting 08/01/2015 at 01:20 #67517 | |
Jersey_Mike
250 posts |
" said:Not sure how you set up block working in the sim, but as I mentioned the ones with signals and trips allow for a reduced overlap. " said: Admission of train to a block via a manually operated signal with procedural control for train spacing. I've been trying to drill down to why the signaling in the UK and many other places was so divergent. Best I can tell you were quick out of the gate with all manner of signalboxes and block working and when electro-mechanical logic and track circuit ABS came around c.1890 you had so much existing plant you folks just kept it in service where as many other parts of the world was able to do directly from timetable and train order to safety systems that were more automated. There is also the system of decentralized operation (trains generally taking charge of their own operation between control points) with centralized supervision (dispatchers dealing with conflicts from a single office) that developed due to the large distances between stations outside of Europe. Up until the 1960's interlockings were still seen as expensive luxuries that most railroads tried to avoid installing. Only as labor costs rose and technology costs lowered did everything go CTC with remote controlled control points. " said: They used to be (remote relay rooms) but with electronic interlockings there is no need. Indeed, surely it would be better to have the interlocking close at hand in case it needs a bit of TLC instead of driving 50 miles or more? Another difference: the link between signallers and their signals, tracks, and points is safety critical (vital) in the UK; in the US many such controls and indications are sent over the airwaves, and AIUI indications cannot be relied upon.Have fun when the Russians or Chinese get into your tubes and start crashing trains. Information security aside, just maintaining vital communications links (and debugging it) is a major pain, especially if you need them to be reliable. Today the state of the art is completely wireless using data radios and signals through the rail. Add some solar panels and each signaling location can be completely off the grid. If they need to (and they frequently do) dispatchers can run the railroad using a telephone and a pad of paper. I think there are also regulatory requirements that prevent the sort of remote logic you folks seem to be going nuts for. For example any change to any part of the SSI software would require EVERY part of the entire SSI territory to be re-tested and certified as well. All that aside just not being tied to a single large central logic center means that interlockings can be transferred and upgraded as atomic units and no single event can wipe out the entire system. " said: (A couple of months ago I used a hand held scanner to "listen" to the over-the-air transmissions while on a train between Seattle and Chicago. While it couldn't see far in front, there was usually enough signal to determine when we would pass another train. Fun and legal)I don't get the concern about open channel communications in the UK. Here having the train crew be able to hear everything is going on leads to better situational awareness. Many accidents have been prevented thanks to one crew hearing something odd on the radio. Log in to reply |
Tower 18 Routesetting 08/01/2015 at 02:07 #67518 | |
Muzer
718 posts |
Of course there is one disadvantage to having large complicated interlockings like we do: http://www.raib.gov.uk/cms_resources/101223-SI2010-MiltonKeynes.pdf Log in to reply |
Tower 18 Routesetting 08/01/2015 at 02:14 #67519 | |
GeoffM
6344 posts |
" said:" said:Ok, when the word "manual" is used it implies old fashioned lever frame boxes. In that case, I'm not sure what your comment means as the US and UK both have forms of automatic signals and manual/controlled signals.Admission of train to a block via a manually operated signal with procedural control for train spacing. " said: I've been trying to drill down to why the signaling in the US and many other places was so divergent.FIFY Railways around the world evolved at different rates with different rules and different requirements. Each suits its own purpose. " said: " said:You've clearly been watching too many movies. :doh The links to the trackside are extremely simple and no part of the interlocking, control equipment, or trackside is connected to the Internet. Or Bluetooth. Or NFC. I doubt one could even write a virus to fit inside an SSI's memory, it is that small.They used to be (remote relay rooms) but with electronic interlockings there is no need. Indeed, surely it would be better to have the interlocking close at hand in case it needs a bit of TLC instead of driving 50 miles or more? Another difference: the link between signallers and their signals, tracks, and points is safety critical (vital) in the UK; in the US many such controls and indications are sent over the airwaves, and AIUI indications cannot be relied upon.Have fun when the Russians or Chinese get into your tubes and start crashing trains. " said: Information security aside, just maintaining vital communications links (and debugging it) is a major pain, especially if you need them to be reliable.And this is exactly why it is so simple. The more complicated you make something, the more effort it takes to debug it, and the more that can go wrong. " said: I think there are also regulatory requirements that prevent the sort of remote logic you folks seem to be going nuts for.The "nuts" to which you refer is what we call "safety". Yes, it is a requirement that the signallers see exactly what is going on. For the US, it's different and is not vital. It's different, that's all. " said: For example any change to any part of the SSI software would require EVERY part of the entire SSI territory to be re-tested and certified as well.Not true. " said: All that aside just not being tied to a single large central logic center means that interlockings can be transferred and upgraded as atomic units and no single event can wipe out the entire system.Transferred to where though? No two interlockings are alike. The hardware can be transferred elsewhere, just as equipment from different manufacturers is supposed to work together. Upgrade? This isn't Windows with the latest fancy gizmos! As for wiping out the entire system, I fail to see any benefit in remotely locating the interlockings. A couple of years ago I was in a Norfolk Southern dispatch center and they were talking about the ability to transfer control to another dispatch center - but it was pointless because nobody in the other centers was trained on this center's areas. Too expensive to maintain competency elsewhere. And another example, several years ago, a lightening strike in Jacksonville, Florida, caused severe delays to commuters 1,000 miles away in sunny Chicago. Remote (trackside) interlockings in both cases, but as much use as a chocolate teapot if there's nobody to control them. " said: " said:Again, it's a requirement that signallers know exactly who they're talking to, at an absolute location: safety. That way accidents are avoided by only the desired recipient receiving what could be safety critical communication.(A couple of months ago I used a hand held scanner to "listen" to the over-the-air transmissions while on a train between Seattle and Chicago. While it couldn't see far in front, there was usually enough signal to determine when we would pass another train. Fun and legal)I don't get the concern about open channel communications in the UK. Here having the train crew be able to hear everything is going on leads to better situational awareness. Many accidents have been prevented thanks to one crew hearing something odd on the radio. SimSig Boss Log in to reply |
Tower 18 Routesetting 08/01/2015 at 02:39 #67520 | |
Muzer
718 posts |
" said:" said:I think the keyword there is "procedural", ie absolute block (where correct procedure ensures safety, at least traditionally) as opposed to track circuit block (where actual train detection ensures safety). I might be wrong though." said:Ok, when the word "manual" is used it implies old fashioned lever frame boxes. In that case, I'm not sure what your comment means as the US and UK both have forms of automatic signals and manual/controlled signals.Admission of train to a block via a manually operated signal with procedural control for train spacing. Log in to reply |
Tower 18 Routesetting 08/01/2015 at 03:43 #67521 | |
GeoffM
6344 posts |
" said:Of course there is one disadvantage to having large complicated interlockings like we do:That had nothing to do with interlocking size - or complexity really. It was a relatively simple, albeit dangerous, cross-boundary data error. This is why we try to eliminate interlocking boundaries! " said: " said:You could be right. But then the US has hundreds if not thousands of miles of unsignalled, non-track-circuited track too - with passenger trains on. Track Warrant Control (TWC) or Direct Traffic Control (DTC). Instructions/permissions/movement authorities and track releases (behind a train) are communicated verbally with both ends having specific forms, confirmation counts of boxes ticked, etc. So it's still comparable to the UK in terms of human fallibility with no detection as backup." said:I think the keyword there is "procedural", ie absolute block (where correct procedure ensures safety, at least traditionally) as opposed to track circuit block (where actual train detection ensures safety). I might be wrong though." said:Ok, when the word "manual" is used it implies old fashioned lever frame boxes. In that case, I'm not sure what your comment means as the US and UK both have forms of automatic signals and manual/controlled signals.Admission of train to a block via a manually operated signal with procedural control for train spacing. SimSig Boss Log in to reply |
Tower 18 Routesetting 08/01/2015 at 03:58 #67522 | |
Muzer
718 posts |
My point is that if the interlocking size was smaller, such errors would be more immediately obvious in testing. I concede that boundaries are probably the hardest bits to test, though, and so simpler and fewer ones are better!
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Tower 18 Routesetting 08/01/2015 at 06:39 #67523 | |
Jersey_Mike
250 posts |
" said:I meant the old lever frame systems where a block operator signals a train based on procedural controls. " said: Some is geography, some is economics, some is culture and some is technology. US and UK signaling looked very similar up through the 1870's and 80's before diverging sharply. I've been trying to pin down the cause of that divergence. " said: The Iranian centrifuges weren't hooked to the internet either and that didn't stop a determined nation state actor. Transmission of vital control messages over a wide area network present a large attack surface. At the very least I hope the messages are properly authenticated (which then of course requires PKI). " said: Well its very fragile. If you lose your link then all your trains stop and you can't get them going again easily. Reminds me of the time I was playing SimSig and I needed a passenger train to wrong rail around a stalled freight and the damn thing wouldn't let me because I had run out of "valid track" or whatever that meant. Someone on a forum said I needed a pilotman which SimSig doesn't support. Why can't I just give the guy a Form D? " said: I'm speaking for the United States. There is an old Conrail high car detector recording at CP-BANKS that had survived 15 years since Conrail went away because its hooked into the interlocking logic and the railroad would have to re-certify the entire interlocking if they changed the recording .wav file. " said: All that aside just not being tied to a single large central logic center means that interlockings can be transferred and upgraded as atomic units and no single event can wipe out the entire system." said: Transferred line ownership to another company. Remember in the US the railroads own the railroads. Case in point. Amtrak just long term leaded the former Conrail, former CSX Hudson Line. They now own all the interlocking hardware and transferred control to their own dispatch office in NYC. If the interlocking logic was a part of some giant central CSX interlocking facility in Albany how the hell would they untangle it all? " said: Upgrade? This isn't Windows with the latest fancy gizmos!If I have a line with 20 control points I can change them out a few at a time without having to mess with some giant area interlocking system that might result in side effects. I can add new ones without having to worry about it affecting anything else. " said: As for wiping out the entire system, I fail to see any benefit in remotely locating the interlockings.If your signaling center burns down then you aren't left scratching your rear end. Centralized logic is the very definition of putting your eggs in one basket. " said: A couple of years ago I was in a Norfolk Southern dispatch center and they were talking about the ability to transfer control to another dispatch center - but it was pointless because nobody in the other centers was trained on this center's areas. Too expensive to maintain competency elsewhere. And another example, several years ago, a lightening strike in Jacksonville, Florida, caused severe delays to commuters 1,000 miles away in sunny Chicago. Remote (trackside) interlockings in both cases, but as much use as a chocolate teapot if there's nobody to control them.CSX has since distributed its dispatch centers due to issues with the Jacksonville office. There's now one in Baltimore near me. (I actually know one of the dispatchers there). Most continuity of operations plans involve moving the existing work force to the new location. Again if the building burns down or is flooded or is hit by a tornado there exists a backup facility you can regroup at. Regarding Tower 18, the interlocking can be controlled from the tower cabin or the relay room. Tower 12 can be controlled by the cabin or Tower 18 or its own relay room. " said: And I'm saying its better that everyone in the area be appraised of safety critical communications in case there is a dangerous condition. Consider the track worker who might hear a signaler give permission to a train to move on his track. North American railroads and rapid transit all use open channel radio and it has never led to confusion. When DTC and TWC was introduced in North America a lot of the old school dispatchers swore it would lead to all sorts of problems because train orders were no longer passed along in writing on multiple different forms. Turns out safety actually improved. If the open channel system is good enough for air traffic control it is certainly good enough for railroads. Aside from the fact that you are sending safety critical messages across wide area networks, I don't consider the UK rail system unsafe, but it is inflexible and very high cost. The entire industry could benefit from some serious innovation of the type seen in North America, South America and Australia over the previous decades. Back to Tower 18...notice how few actual points of signaling control there are on that simulation compared to the British Tower 18 (wherever that is). There might actually be more hand operated switches than power operated switches. See, that's all cost savings. Single ride on the CTA is 1 pound 50. What it is on the LUL these days? Log in to reply |