Please improve performance of double track

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  • #16550
    Martin955
    Participant

    Adding passing loops is usually ok, but with longer stretches of double track the trains sometimes refuse to use the second track, then start to jam up. This is really annoying.

    Sometimes I can fix this by demolishing and making a new connection, sometimes not. Players need to be able to select how much track to bulldoze – at the moment you may have to remove long stretches of track.

    Trains leaving a depot onto double track should go in the right direction on the right track. If locomotives can ‘magically’ run round their trains, could you do something similar to get from a depot to the right track?

    I am finding the game intriguing, but it feels unfinished. If I can cope with implementing the ‘mods’ it will definitely improve.

     

    #16553
    isidoro
    Participant

    If you want to make the trains use the right hand track of a double track, you can use one-way signals for it.  They only allow trains to pass them in one direction.  You get them by clicking on the signal once built and select the option.

    There is a trick to allow you to demolish smaller sections of tracks or roads: just make a crossroads in the point you want to stop demolishing.  You can then demolish the segment up to the crossroads.

     

    • This reply was modified 5 years, 12 months ago by isidoro.
    #16560
    Martin955
    Participant

    Isidoro

    Thanks for your response. I have been playing with routes and signals.

    Need to get trains from a depot onto both lines, now.

    #16562
    Norfolk_Chris
    Participant

    You can specify the exact path your trains take by using waypoints.  You can insert specific way points (signal menu), or use any signal.  You map the waypoints in the same way as you map stations when mapping the line.  I works, I use this method all the time to avoid the problems you are having.

    #16574
    simonmd
    Participant

    As said above, waypoints and signals will get your stock on the right track, you’re obviously not using them correctly. Have you tried the ‘one way’ signal option?

    For bulldozing smaller sections, this can be a pain but there is a work around and this applies to roads too. Build a new small section of track/road at the approximate place you want to bulldoze upto then you can just delete the section upto that point.

    #18027
    Anonymous
    Inactive

    I seem to be having this problem too.

    I tried all sort of combination but the trains AI will always try to use the shortest route, instead of parallel routes on multi-tracks lanes, with switch connections across all 4 or 5 lanes

    Trains still jams up trying to use the first lane, even when a passing option is available to switch to the other lanes.

    I’ll try to waypoints signals to see if it makes any difference, since traffic lights doesn’t seem to be doing much in that regard.

    #18032
    Pasi
    Participant

    Waypoints will force the path to where ever you want, so use them. And if you want trains out from the depot to both directions, it’s easiest to do 2 depots. Or, simply place the depot at the end of the platform on the last stop on the line.

    Since the auto update feature, i’ve never returned any trains to depot anymore.

    One way signals on right places and waypoints work wonders. And build bigger stations and avoid using the same platform for more than 2 lines.

    #18068
    Varana
    Participant

    Trains still jams up trying to use the first lane, even when a passing option is available to switch to the other lanes.

    Trains in TF will never ever stray from the assigned line. If that is occupied, they wait. There is no such thing as switching to a free track. If you want them to run on another track, you have to use signals or waypoints to force the whole line (in one direction) on the desired track. Trains serving that line will then use that track – exclusively.

    Trains do not switch tracks dynamically, period. 🙂

    #18072
    bythelee
    Participant

    When trains jam up (“waiting for free path”), they will randomly switch tracks if the other track is empty, and convenient track switching is available. Each train dynamically searches for a clear path to the next stop, and does not care which platform it uses when it arrives. This is what you need to consider, whenever adding switches and multiple track alternatives that a train can use to reach its next stop.

    I typically prefer to build a double track loops, and run trains in both directions (clockwise and anticlockwise). But even this was not enough, as the Lines would randomly switch track (random changing from left hand drive to right hand drive) and the trains would get into horrible messes trying to change over. I tried using signals, and waypoints, all to no avail. I did not know that all signals were bi-directional by default, and merely divide a length of track into two sections.

    But using One Way signals, specifically setting each signal to “one way” (select “yes” in the dialogue box that pops up when you click on a traffic light signal) sorted that problem entirely. The lines now remain fixed on each track, and the trains run perfectly. Note that just one signal is adequate to force the direction of each track (and the line that runs on it), if there are no points/switches linking the two. I’m also now in the habit of building a depot on each side of the doubletrack, one for each direction, to avoid the need for trains to ever cross tracks, but that is unnecessary with correct signals.

     

    To force the exclusive use of longer stretches of double track, add a single signal to the outside of each track, just before the points (switch) at each end. Trains will need to stop while on the double track if the single track ahead is blocked by another train. TF prefers the “left hand drive” track usage, so place your signals accordingly, but it really doesn’t matter for the “passing loop” situation. I’d stick with convention, in case of an eventual upgrade to full doubletrack.

    Once built, click on each of the two signals and select the “yes” option to the “One way” question. Any train approaching from a single track section will examine the two tracks ahead, and discover the left hand track is obstructed by the one way signal close by, while the right hand track is permitted by the one way signal that allows it to pass at the far end of the double track. The train will always smoothly choose the only track available.

    You can add more signals along the length of the double track to “stack” waiting trains. Just make sure that you always build signals on the outside of the double track.

    Note that it is only necessary to set ONE signal on each track to “one way” to force the exclusive selection by each train. Setting them all to one way is not a problem, except that if you make a mistake with signal placement, you might end up blocking the track by making it one way in both directions (ie unpassable) with conflicting signals.

    One way signals have given me all of the control I need. Waypoints should also work, but they are not direction dependent, and can be passed / ignored by trains that are not required to pass through them. They will force trains on that line to use that track, but they do not stop other trains from using it too, nor do they control direction, and that’s how the jams can still happen. Forcing all lines to use the correct waypoints at the correct moment is much, much harder than controlling the track usage with one-way signals. Waypoints also caused problems when trains advanced on the wrong track because it was free, only to have to reverse to one of the rare switches I had, to get onto the other track for the required waypoint.

    In a nutshell, careful placement of one-way signals, will always guarantee which trains use which section of double track. Whenever you have switches that allow trains to change tracks, you need to consider whether one-way signals are needed to control which track a train will choose.

    While I agree that double track performance is lacking (especially the line planning randomly changing the track it prefers), the trivial effort to build one-way signals to sort all of that out, is effortless compared with building the track itself.

    #18077
    electricmonk2k
    Participant

    Need to get trains from a depot onto both lines, now.

    You just need to build a crossover (a track leading from one of the two tracks of a double-track line to the other) just after the point where the track from the depot joins the first track of the double-track. That way, it can easily cross onto the second track. As long as you put signals both before and after the two switches on the depot-side (but not on the track leading to the depot), and before and after the one switch on the far-side, then the path from either side to the depot will be two way (ie. the entire signal block will be two-way), whereas the rest of the double-track should be one way each side if the signals are set up correctly.

    If you want the trains to be able to reach the depot from either direction, you need  to split the line leading from the depot before it joins on to the main track, and the new branch will join the main track facing the other direction (where you repeat the steps mentioned before to mirror what you did previously).

    #18080
    isidoro
    Participant

    @bythelee: if I understand you correctly, if you have two models of locomotives in a line, you can get the fast one overtake the slow one by just doubling the tracks and platforms between two stations… is that true?  I have tried to do it myself but the trains kept choosing always the same track of the two and they queue up…

     

    #18081
    vinkandoi
    Participant

    I am successfully running a high speed line between 2 stations that have low speed line also. You will have use seperate tracks even though the station platform is the same

    Waypoints is the answer. You can place waypoints on tracks (waypoints are available in the signal section of construction). You can add waypoints as stops.

     

    #18088
    bythelee
    Participant

    @isidoro No, that isn’t what I was doing (or intending). My plan was to have each of the two tracks running trains in opposite directions. All of the trains on one line were confined to a single track, much like cars travelling on a two-way road.

    Thinking like a passenger, I would not want to get on a train that travels all the way around a loop, just to get to the next station “upstream”. That’s why I run trains in the opposite direction too. All of the London Underground trains do that. As do most, if not all, subway systems. And bus routes. And tram tracks. Passengers usually need to make the journey in both directions. I’m not certain if TF simulates this accurately, but seeing passengers waiting at a stop wanting to make a commute from workplace to home, it looks possible. The game might let them use alternative means for each journey, and not require both to use the same mode of transport. I suspect so, because I rarely see even usage of the contra-rotating lines. One is often as little as 1/2 or 2/3 of the other. But I digress.

    So, I typically have full dual track, and do not need to have switches. I often have some, though, because once the first few stations are built and linked, I will set a train or two running, shuttling back and forth along the incomplete loop. I don’t remove those switches, and things got messy much later once both loops were completed, and each line was running five trains. I built a track segment for a new line, not even physically connected to the first ones, and TF decided to swop those two lines over, onto each other’s track. Ten trains now tried to maneouvre onto the other track, using the few bits of switchtrack I had left in the early build. Total chaos and logjam. Much has been written about this random line switching in other threads/posts, and it was here that I first read about “one-way signals”. They are a lifesaver. I have not had a single problem since converting the two-way signals that I had expected to do that job, into one way signals. The lines remain on the tracks they were assigned to, and trains no longer attempt to use the wrong track.

    When I said “the train can pass at the far end” I meant that the train can pass by the one-way signal, not a slower train. When a train finds two alternative tracks provided by a switch, then a one-way signal either says “welcome” or “no entry”.

    A two way signal (the default setting) says “welcome” in both directions, but divides up that track into two segments, splitting it at the signal. A train can use that track from either direction, so long as another train is not presently occupying it. It sounds confusing, but it isn’t once you get your head around it. If you have a two way signal at each end of a track segment, then with unfortunate timing, you can get trains entering the switches at both ends, seeing the segment up to the signal as clear, but then jamming as each one tries to use the segment between the signals. They will face off against each other, neither one winning. One of them will have to reverse (requiring manual user intervention) to resolve it. I found it easier to quit and restart from an earlier save than fix my line switching logjam, and sorted out my one way signals instead.

    But I also know, that trains do not have to stick to the track indicated by the coloured line, for them to achieve the route. An early section of dual track loop with no switches, and a reciprocating line running one train, had the train running on the track not indicated by the line. It stopped at stations, and carried passengers regardless. So, trains can choose alternative paths to the ones indicated by the line, which makes your trains refusing to attempt an overtake very interesting indeed. I’d have all sorts of questions about the speed difference between the trains, and relative distances, and how close the chasing train was before it had a chance to pick the alternative track. There is also the dreaded issue of whether the alternative track was suitable for use. Like, a missing sliver of electrification that prevented an electric train from using it. (I’ve hit that nasty “feature” before too – my trains started reversing around the entire loop to get to the next station, jamming against the other trains still advancing normally. Such joy…. lol)

     

    If you want to have high speed trains passing slow ones, then it gets difficult, but not impossible. You would need dual track heading in the same direction. And I suspect it needs to be quite a decent length, depending on the speed difference. The less the difference, the longer the track needed.

    Unlike “clever” signals, whereby a slow train could be held at a signal while the fast one caught up and went by, TF only has a “first come, first served” signal system. Whichever train gets first call, gets to go. So the fast train has to catch and pass the slow train in time for the next track segment.

    The slower train sets off down one of the tracks, letting the faster train take the other track and attempt to overtake it. The doubled track has to be long enough, and the preceding signals and stations and single track segments short enough, that the fast train could get close enough behind to have a go at passing. It will always wait for the slower train to fully clear the segment of single track it is on, before the faster train can enter it.

    If the dual track is long enough, it should catch and pass the slow train, and enter the next single track segment first. But it is not clear at what point the slow train scans ahead for the next clear segment. Trains slow down and stop in time time for signals, so I think they “know” whether the next segment ahead is clear or not. In which case, you would need to add extra signals to break the track up into multiple segments. Otherwise, as soon as the slow train enters the dual track, it already checks ahead and sees the next segment at the joining together switch is clear, and “pre-books” its place. Even if the fast train overhauls it, the joining switch is already commandeered by the slow train, and the fast train will stop and wait. If you add signals just before the switch, then each train merely pre-books the segment between the signal and the switch. So if the fast train can pass its signal first, it will get first call on the segment beyond the signal-switch segment, and happily prebook the switch segment before the slow train gets there. Overtake made, mission complete.

    It’s all about speed. The dual track has to be long enough to let the fast train overhaul and reach the next signal first. The preceding segments have to be short enough (you can add multiple signals every train length to permit this if need be) to let the fast train get close to the back of the slow train. If the fast train is held back a long way because of the long length of the segment approaching the switch, it will have to make up too much ground to get past. If the slow train ever gets to the switch before the fast train, the overtake is a bust. Your situation sounded like the game never even tried to use the other track, so it’s unclear if this can ever be made to work automatically.

    Waypoints can certainly help, especially if the fast train gets to use a high speed track. Consider forcing the slow train onto a slow track, and let the fast train use a high speed track. So if you have upgraded the track to high speed, add a parallel slow speed track, and use waypoints to steer the slow train onto that. You will have to double up the line definition, because all trains using that line will have to pass the waypoint, so if both fast and slow trains are on that line, they will both have to pass the waypoint and use the same track, ignoring the passing track. A second waypoint, and a duplicate line except for the waypoint, is the way to resolve that. But that feels…. messy. And will not fix the fundamental “fast enough to overtake” speed problem, if the segments are not short/long enough.

    I’m thinking the fast train / slow train overtake is sensible only when you have slow goods trains sharing some part of a high speed passenger track, and want to avoid holding up the passenger train while the goods train is passing through. Otherwise, it makes much more sense to have a fleet of the same trains running on any one line.

    While I did have a temporary situation where I ran newer, faster trains on the same lines as older, slower ones, I swopped all of them for one type of train as soon as possible. That way, they all run at similar speeds, and spread themselves out reasonably well, with minimal signals. Signals only become necessary when you want to run more trains than stations, to provide more track segments for the trains to fit on. And sometimes, if you have one or two unusually long runs between stations, it can help to break up that long run into similar lengths as the typical station-to-station distance. Signals are an easy way to do that. Switchtrack is another, whether or not the switches go anywhere. Stations break it up too, but they are not the right tool for that job. From a quick test, waypoints do NOT divide up a track segment – they merely force a line to use that track segment. Trains do NOT wait at a waypoint.
    The simple rule is, that trains will not enter the next track segment ahead, unless the path is clear for them to do so. And trains have foreknowledge about the state of the next segment (whether it is blocked by another train, or clear). So, they know whether to stop or carry on when they reach it. You might have to provide a “dummy” segment between a signal and the switchtrack at the end of an overtaking lane, to make it more likely that the fast train get past the slow one. Merely having a dual track with switchtrack at each end impedes the fast train overtaking the slow one. Because the uncertain point at which the trains pre-book the next available segment almost certainly precedes where you’d place a signal.

    I’d screengrab an example, but my screengrabber merely gets a black screen instead of a jpg. And no, this isn’t a steam version, so F12 doesn’t work. I got mine from GOG.

    #18099
    isidoro
    Participant

    Interesting!  My use case happens when I have a running line and a new faster locomotive appears, but I don’t want to change all my trains at once.  If I only change one of them, its higher speed is useless, since it will always go below the other slower trains.  If I were able to build such overpasses, those would allow the faster train to take advantage of its speed.

    I can’t use waypoints (it means two lines: one for faster, one for slower vehicles), besides micromanagement, because frequency in both lines would get spoiled.  To keep the original frequency or ever a better one, I have to be able to do it in one line…

     

    #18126
    bythelee
    Participant

    @isodoro In theory it should work. But depending on how much faster the new trains are, the length of overtaking track might be prohibitive. It could prove very difficult to get it working in practice, but I am going to experiment, to see if it works. I’d like to better understand the logic behind when a train checks for a clear path, and whether a train can be persuaded to move off the track chosen by the line because the alternative path is clear.

    I agree – having some fast trains is pointless, because they always jam up behind the slower trains. It’s not too bad if the newer trains are only a little faster, but have better capacity, or running costs. But it’s the reason why I prefer to switch all of my trains to the same type as quickly as possible.

    I also agree that the micromanagement of lines to add waypoints feels prohibitively awkward. I already spend far too much time tweaking routes and adjusting vehicle updates. But it is a way to guarantee which trains select which tracks. Whether the layout permits overtaking, remains a speed/distance calculation problem, though.

    Personally, I suspect that the expense of changing all trains to the same type, is less trouble than building a working overtaking track. I use the automatic vehicle replacement tab on the Line window a lot. Select the appropriate vehicle, then switch it to replacing at 25% life. You get about half of the old train’s value refunded when it is sold, the trains update automatically at a station, maintaining the passenger counts and smooth running of the line, without needing the manual intervention of sending trains to depots and buying new trains to replace them. Usually the existing fleet is already old enough for an instant replacement when something appropriate to replace them turns up.

    I do the same trick for trucks, buses and trams. But only when a really interesting / useful new vehicle is released. Like a bus with twice the speed and more passengers, for intercity haulage.

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