Yooski Posted December 14, 2017 Share Posted December 14, 2017 Hello Everyone, I was wondering when a mainline has bi-directional signalling as a redundancy (so not used all of the time) what signals are placed on the "wrong running line" facing the wrong way and are the signal distances the same? For instance does the wrong running line have ground signals or 3 aspect signals or normal 4 aspect signals? Just looking for inspiration and a reason to run trains on the wrong track either direction Link to post Share on other sites More sharing options...
Yooski Posted December 14, 2017 Author Share Posted December 14, 2017 I should add this is a modern day question with 3/4 aspect LED lights Link to post Share on other sites More sharing options...
dmustu Posted December 14, 2017 Share Posted December 14, 2017 You generally get one of two set ups on bi-directional lines. Either full signalling that is basically a copy of the signalling fitted to the normal running line, so if it 4 aspect in the 'right' direction, it will be 4 aspect in the 'wrong' direction, with signals fitted opposite each other, or a basic version called SIMBIDS (simplified bi-directional signalling). With simbids, you get less signals in the wrong direction compared to the right direction, and these are more often than not 2 aspect signals, yellow/green 'distant', and a red/green 'stop' signals. Link to post Share on other sites More sharing options...
Yooski Posted December 14, 2017 Author Share Posted December 14, 2017 Thank you Link to post Share on other sites More sharing options...
RMweb Premium ba14eagle Posted December 14, 2017 RMweb Premium Share Posted December 14, 2017 You generally get one of two set ups on bi-directional lines. Either full signalling that is basically a copy of the signalling fitted to the normal running line, so if it 4 aspect in the 'right' direction, it will be 4 aspect in the 'wrong' direction, with signals fitted opposite each other, or a basic version called SIMBIDS (simplified bi-directional signalling). With simbids, you get less signals in the wrong direction compared to the right direction, and these are more often than not 2 aspect signals, yellow/green 'distant', and a red/green 'stop' signals. I used to work Swindon Panel and our lines were SIMBIDS fitted. The signals on the reversible were few and far between and only 2 aspect. Using the reversible line for overtaking manouvres, of slower trains, used to be a complete but was authorised a few years ago - the benefits to performance must have been realised! Link to post Share on other sites More sharing options...
Yooski Posted December 14, 2017 Author Share Posted December 14, 2017 Would the speed limit be reduced on the "wrong line" due to the signal distances and the fact that they where two aspect? Link to post Share on other sites More sharing options...
RMweb Gold big jim Posted December 14, 2017 RMweb Gold Share Posted December 14, 2017 The line between crewe and Wilmslow and crewe and shrewsbury are both bi directional and the ‘wrong direction’ signals are a mirror of the ‘right direction’ ones, the wilmslow line has the same line speed on both lines (100mph) but the shrewsbury line is slower on the wrong direction line The chiltern mainline is bi di between anyhoo and risborough hutvthe bi di line only has 1/2 the signals as the right direction line, once you enter it at risborough it’s a good 8 miles to the next set of signals at ashenden jn Link to post Share on other sites More sharing options...
RMweb Gold The Pilotman Posted December 14, 2017 RMweb Gold Share Posted December 14, 2017 (edited) Would the speed limit be reduced on the "wrong line" due to the signal distances and the fact that they where two aspect? In the 1980s and 90s the Reading PSB controlled section of SIMBIDS from Foxhall Junction (Didcot West) towards Swindon had speeds of 125mph in the normal direction and 80 or 85mph on the bi-directional. As far as I recall, the only occasion that required cautioning drivers before using the bi-directional facility was if you were going to send a down train on the up line and an up train on the down line (so they would pass each other on the wrong side) but I never saw that done and can’t really think of any good reason why anyone would need to do that. Edited December 14, 2017 by Western Aviator Link to post Share on other sites More sharing options...
Rugd1022 Posted December 14, 2017 Share Posted December 14, 2017 (edited) The Midland Mainline south of Leicester as far as Wellingborough is signalled for bi-di working with equal spacing on both lines, plus the line speed is the same throughout. I've down it several times in the past, usually at night. Edited December 14, 2017 by Rugd1022 Link to post Share on other sites More sharing options...
RMweb Gold big jim Posted December 14, 2017 RMweb Gold Share Posted December 14, 2017 I did an IM train 30mph ‘wrong direction’ from rugby to Lichfield a few months back, that was certainly a strange experience being as trains were passing me on the down fast and slow lines as well as the up slow! Link to post Share on other sites More sharing options...
Yooski Posted December 14, 2017 Author Share Posted December 14, 2017 Thanks everyone for the input. I have decided that I will place half of the usual signals on wrong direction track and reduce their aspect to 3 (from normal 4) with a reduced speed limit! Thanks again! Link to post Share on other sites More sharing options...
RMweb Gold RFS Posted December 14, 2017 RMweb Gold Share Posted December 14, 2017 Worth watching part of this cab view from London Bridge, as the train is travelling reversible lines for the first 4-5 minutes - https://www.youtube.com/watch?v=sE04Faxfo7I. Seems you need plenty of points - especially scissors crossovers - to get it to work! Link to post Share on other sites More sharing options...
RMweb Premium phil-b259 Posted December 14, 2017 RMweb Premium Share Posted December 14, 2017 (edited) A practical example of SIMBIDS as installed in the mid 1980s is shown in files 1A and 1B In this example only ONE TRAIN may proceed on each line through the entire area covered by the SIMBIDS scheme. On todays busy railway this makes SIMBIDS practically useless as a method of keeping the train service going. Edited December 15, 2017 by phil-b259 Link to post Share on other sites More sharing options...
RMweb Premium phil-b259 Posted December 15, 2017 RMweb Premium Share Posted December 15, 2017 (edited) And an example where SIMBIDS has been upgraded to the halfway house stage. Not full bidirectional working but more wrong road signals so as to allow up to 4 trains to proceed wrong line at once. A superficial glance would suggest that full bi-directional working has been installed... BUT THIS IS NOT THE CASE! Due to the standards having changed since the mid 1980s we are not allowed to have some signal configurations today which were permissible back then. Hence the appearance of what should actually be yellow / green repeater signals that have a red aspect but are marked as signal XXX not approachable at Red. Basically in normal working situations (Down the Down and Up the Up) the wrong road signal will show a red aspect (done so as to prevent a driver making a mistaking it for the right direction signal they should be obeying and rear ending the train in front are). However once bi-directional working is enabled then the signalling system will treat the wrong road signal as an ordinary yellow / green repeater and not let any train approch it unless it is showing the said yellow or green aspects. It doesn't help that most signal heads or of the twin LED style thus making the diagrams harder to read. Edited December 15, 2017 by phil-b259 Link to post Share on other sites More sharing options...
caradoc Posted December 15, 2017 Share Posted December 15, 2017 When the Paisley/Ayr line was resignalled in the 1980s for electrification, bi-directional signalling was provided between Elderslie and Kilwinning, however similar to the example phil-b259 mentions above, signalling was only provided to enable one train at a time on the 'wrong' line between crossovers. Whenever we had an incident blocking one line and had to use the bi-di, the maximum passenger service possible was half-hourly each way, whereas the booked service then was four per hour, and is now six. And the only way to get a freight through was to reduce the passenger service even further, although this is no longer a major issue since the closure of Longannet Power Station and then end of traffic to and from Hunterston. In contrast, when the additional line was installed between Shields Jc and Paisley (for the cancelled Glasgow Airport link), full signalling was provided on all three lines in both directions. Link to post Share on other sites More sharing options...
Ken.W Posted December 15, 2017 Share Posted December 15, 2017 (edited) The ECML has quite extensive SIMBIDS working, Northallerton to Low Fell, and Benton Jn to Tweedmouth (the bit in between, roughly 5 mile either side of Newcastle, and Tweedmouth - Berwick are fully Bi-Directional). As stated, it's only intended for emergency purposes, such as getting round an obstruction, failed train, track defect etc., where Pilotman's working would otherwise be necessary, not normal traffic purposes. As such, although it's more restrictive of capacity than normal signalling (besides the fact when in use you're only using a single line to start with), it's still much better than the alternative. There's usually just one intermediate stop signal in each section between crossovers, usually 2 aspect, and a Y/G repeater, both sited opposite the corresponding right-direction signals. On some stretches, particularly the 'North' road, there are more intermediate Bi-Di signals where there's level crossings etc to protect, to the point some sections are vitually 3 aspect. The signals that can put you back onto the right line are always at least 3-aspect as this is putting you back to normal signalling and signal spacing. One point not mentioned previously, SIMBIDS signals are not provided with AWS equipment, though the AWS for the correct direction signals aren't suppressed for wrong direction movements so have to be canceled on passing over each one. Although full Bi-Di can be anything up to full linespeed, the maximum for SIMBIDS working's 50mph The two systems can even be mixed - Cockburnspath Bank, between Dunbar and Berwick's equipped with Bi-Di working between Innerwick and Grantshouse, however, while the Up direction (also uphill) has full bi-di over the Down, allowing uphill freights to be routed bi-di to be overtaken, and signals opposite each right direction signal, full AWS etc., the Down direction only has SIMBIDS over the Up Edited December 15, 2017 by Ken.W Link to post Share on other sites More sharing options...
RMweb Gold big jim Posted December 15, 2017 RMweb Gold Share Posted December 15, 2017 The bi-di between shrewsbury and nantwich is the latest hi-tech set up, obstacle detector crossings, computer control etc the only thing is to get on to it from the shrewsbury end you need a pilotman to get you out of the station to the first signal! Link to post Share on other sites More sharing options...
luckymucklebackit Posted December 15, 2017 Share Posted December 15, 2017 The ECML has quite extensive SIMBIDS working, Northallerton to Low Fell, and Benton Jn to Tweedmouth (the bit in between, roughly 5 mile either side of Newcastle, and Tweedmouth - Berwick are fully Bi-Directional). As stated, it's only intended for emergency purposes, such as getting round an obstruction, failed train, track defect etc., where Pilotman's working would otherwise be necessary, not normal traffic purposes. As such, although it's more restrictive of capacity than normal signalling (besides the fact when in use you're only using a single line to start with), it's still much better than the alternative. There's usually just one intermediate stop signal in each section between crossovers, usually 2 aspect, and a Y/G repeater, both sited opposite the corresponding right-direction signals. On some stretches, particularly the 'North' road, there are more intermediate Bi-Di signals where there's level crossings etc to protect, to the point some sections are vitually 3 aspect. The signals that can put you back onto the right line are always at least 3-aspect as this is putting you back to normal signalling and signal spacing. One point not mentioned previously, SIMBIDS signals are not provided with AWS equipment, though the AWS for the correct direction signals aren't suppressed for wrong direction movements so have to be canceled on passing over each one. Although full Bi-Di can be anything up to full linespeed, the maximum for SIMBIDS working's 50mph The two systems can even be mixed - Cockburnspath Bank, between Dunbar and Berwick's equipped with Bi-Di working between Innerwick and Grantshouse, however, while the Up direction (also uphill) has full bi-di over the Down, allowing uphill freights to be routed bi-di to be overtaken, and signals opposite each right direction signal, full AWS etc., the Down direction only has SIMBIDS over the Up i have always felt that that the signalling at Grantshouse loops is a bit over the top, with all four tracks (two main and two passenger loops) bi-directional. Jim Link to post Share on other sites More sharing options...
caradoc Posted December 15, 2017 Share Posted December 15, 2017 The two systems can even be mixed - Cockburnspath Bank, between Dunbar and Berwick's equipped with Bi-Di working between Innerwick and Grantshouse, however, while the Up direction (also uphill) has full bi-di over the Down, allowing uphill freights to be routed bi-di to be overtaken, and signals opposite each right direction signal, full AWS etc., the Down direction only has SIMBIDS over the Up I recall one occasion when two Up freights left Millerhill for the ECML in quick succession; For operational reasons the Operator wanted their order reversed, so the first train ran via Simbids over the Down from Innerwick to Grantshouse, allowing the second train to overtake (there wasn't much other traffic about at the time !) Link to post Share on other sites More sharing options...
RMweb Premium ba14eagle Posted December 15, 2017 RMweb Premium Share Posted December 15, 2017 Would the speed limit be reduced on the "wrong line" due to the signal distances and the fact that they where two aspect? IIRC speed was 85mph in the reversible direction Link to post Share on other sites More sharing options...
RMweb Premium Reorte Posted December 15, 2017 RMweb Premium Share Posted December 15, 2017 Are these sorts of bidirectional running a (relatively) modern thing or did it exist in some form when such major lines were controlled by semaphore signals (i.e. outside of stations)? Link to post Share on other sites More sharing options...
Rugd1022 Posted December 15, 2017 Share Posted December 15, 2017 (edited) Definitely a modern thing in the main, the MML section I mentioned earlier didn't exist until the mid to late '80s.The section between Rugby and Nuneaton has been around for years but the newer bi-di section north of there wasn't commissioned until the about ten years ago.The first time I had to go bi-di to Lichfield it was was quite an eye opener! Edited December 15, 2017 by Rugd1022 Link to post Share on other sites More sharing options...
Foulounoux Posted December 15, 2017 Share Posted December 15, 2017 Check out the simsig range of signalling simulators. These use real accurate information in their creation and some have bidirectional signalling Link to post Share on other sites More sharing options...
RMweb Gold big jim Posted December 15, 2017 RMweb Gold Share Posted December 15, 2017 The first time I had to go bi-di to Lichfield it was was quite an eye opener! It sure is!! Also on the old bit between rugby and nuneaton flask trains weren’t allowed to work wrong direction on the up fast Link to post Share on other sites More sharing options...
RMweb Gold The Johnster Posted December 16, 2017 RMweb Gold Share Posted December 16, 2017 The Badminton cut off was done in the 70s, but at that time 125mph HSTs were sharing it with 45mph part-fitted freights. IIRC the Severn Tunnel was done around that time. Link to post Share on other sites More sharing options...
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