May 21, 2009

OpenTTD: Trains and signals for beginners – a tutorial

Posted in Misc at 08:22 by graham

I have been playing Open Transport Tycoon Deluxe, or OpenTTD on and off for a while, but I confess I only understood train signals very recently. The game gets a lot more fun once you can have complex track layouts, so here’s a tutorial on train track layout and signaling for complete beginners.

Building tracks the wrong way

If you’re anything like I was, all your train layouts probably look like this:

one-to-one

You can only run one train on that track, but say you’re happy with that. When you need to connect another station, you might, unsuccessfully, try this:

two-stations-naive

Notice the three two-way signals. A signal locks an entire section of track from that signal until the next signal or the end of the line. These signals define four locks, color coded on this screenshot. If the train from Lundinghattan Ridge is in the Mardingbury station, it will have a lock on the yellow section, but not on the green section. The signal nearest Mardingbury will be red, but the other two signals will be green. The train from Marbourne will be able to acquire a lock on the green section, and stop at the signal nearest Mardingbury. We have a train stand-off. Not good.

To make that layout work, you’d need to remove the signal nearest Mardingbury, thereby merging the green and yellow sections. You remove that, and you have two trains sharing a station. OK, so now you add a third station to your network. Now things really start to break down.

blocked

The blue section is shared between the Lundinghattan train and the Chenningpool train. The Lundinghattan train is top left, just leaving Mardingbury station. It has the lock on the yellow section. Notice the two signals nearest it are red (actually all the signals in this picture are red, but focus on just those two). The train from Chenningpool acquired the lock on the blue section, but and this is the first important concept of this tutorial, once it got level with the depot it had a choice of two paths: Mardingbury, which is blocked by a red signal, and the depot, which isn’t. A train faced with a red two-way signal will always avoid that signal, even if that means going away from it’s destination. If instead of the depot we had a track running to the other side of the map, our Chenningpool would of happily headed down it, to avoid the red signal.

In practice this means our Chenningpool train will head into the depot, turn around, and head back to Chenningpool. It will never make it to Mardingbury. There is something very wrong with our approach, and the short answer is that we were using two-way tracks and two-way signals. We need to think one-way. Let’s start again.

The basic loading loop

Every shared station should have a one-way loading loop.

loading-loop

Notice the signals around the loop are all one-way. To place a one-way signal place a signal as normal, then click the signal again, once or twice depending on the orientation you want for your signal.

Now let’s connect our loop up to a town, and run two trains betweens those two towns.

shared-track1

We connected the shared track from Marbourne to our loading loop, with two short one-way sections. We can see the back of a one-way signal in the red circle, and the front of a one-way signal just to the right of the blue circle.

Let’s look at what’s going on in this picture. The train circled in red has the lock on the red section of track, and is held at the signal circled in red. It is waiting for a lock on the blue section of track. Notice that it could of kept going around the loop, instead of branching off and stopping at the red signal. Faced with a red one-way signal and a clear track going the wrong way, the train will stop at the signal, which is nearly always what we want. This is exactly the opposite to what would of happened with two-way signals.

The train circled in blue has the lock on the blue section of track, and is about to acquire the lock on the yellow section. As soon as it does, it will release the lock on the blue section, and the train circled in red will move forward. This is a layout that works.

Prefer one way tracks

Let’s connect up the other two towns, and not get blocked this time. The trick is to make all shared sections of track one-way.

one-way

The only two-way signals in this picture are circled in blue. All the others are one-way. The two-way signals are there to prevent a train on the two-way track from locking part of the one-way loop. If the left-hand two-way signal was not there, a train in Lundinghattan station would hold a lock on it’s two-way section of track, and the bottom part of the one-way section, up to the next signals. Remember, a lock is between two signals or the end of the track. Incidentally, stations don’t end a lock. If you had a station half-way along a track, the lock would run right through it until the next signal.

Pre-signals, the pro-layout

Mardingbury is getting quite busy now, we’d like to have two tracks in the station. Stop all the trains (or be quick!), bulldoze the station, and build a new, two track one. I moved mine back a square to allow space for the tracks to merge. and made the loading loop a little bigger. To control access to a multi-track station, you need pre-signals.

Pre-signals come in two types, entrance and exit. An entrance pre-signal will be red if all the exit pre-signals behind it are also red. The motivation for pre-signals is nicely illustrated here: Pre-signals on the OpenTTD wiki.

pro1

The entrance pre-signal is circled in blue. Notice that it has a horizontal white-bar, to show it is different. The exit pre-signals are circled in purple, and have vertical white bars. There is currently a train in the station, so one of the exit pre-signals is red. Because one of the tracks is free (green signal), the entrance pre-signal is green. The next arriving train will correctly go to the empty track. Even though they are pre-signals, we are still using one-way signals

What you can’t see on the picture, but which are very important, are the two normal one-way signals circled in black. They control station exit, by forcing a train wanting to leave the station to acquire a lock on the yellow section. This prevents two train leaving at the same time crashing into each other.

When a train is in the station, it still holds a lock on it’s section of track. The lock runs from the exit -pre-signal at the entrance to the station, to the regular one-way signal at the exit of the station.

Scaling it up

You now know all the key concepts, the rest is just more of the same. Here for example is what you would do if Lundinghattan got busy.

two-loading-loops

You give it a loading loop, and a multi-bay station. Pre-signals control station entrance, and regular one-ways control the exit. You can see the one-way’s at the exit much better on this station.

There’s one final change we need to make to allow lots of trains – we need to replace the two-way section highlighted in blue with two one-way sections.

pro-final

We don’t have any more two-way signals. Each station has a loading loop, and one-way tracks connect the stations. In our first tries we had one track connecting the stations, and could only run one train between them. Now we have two tracks connection the stations, and in this picture alone there are eight trains, all serving Mardingbury. Now that’s more like it!

The stations are quite close together, so it might not be clear what is loading-loop and what is the tracks that connect them, so here’s an example with stations further apart.

pro-big

Other stations would have their own loading loops, and as long as the one way tracks connect, you end up with a network spanning the world. Trains can run from anywhere to anywhere, and new stations just need plugging in to the network.

I have one final tip: Playing with virtual toy trains can be quite addictive, so remember to get some sleep :-)

28 Comments »

  1. David said,

    December 12, 2013 at 02:00

    How do you signal 2 switches off 1 main that are less than 10 cars apart that are on the same side? and 1 on each side?

  2. Frabac said,

    October 1, 2013 at 08:23

    Great tutorial, thanks. Latest pages on OpenTTD wiki are already very clear but these are very good “everyday” examples.

    Thanks again!

  3. Mark said,

    January 29, 2013 at 12:01

    @Ryan Really? After nearly 4 years of publishing? A lot of people found this helpful, if you can’t get you’re head around it then you’re simply being lazy. However, for the colorblind it could indeed be better if there were also characters assigned to each part of the track.

  4. Ryan said,

    January 19, 2013 at 03:31

    You need to make a key for the different colors you used to demonstrate the different types of signals. All I am seeing is random colors and a short explanation.

  5. Mark said,

    December 27, 2012 at 21:52

    Good tutorial. Finally understand what the exit-signal is for, simply by deliberately using a normal signal while reproducing your examples. And the last sentence, about getting sleep, could not be stressed enough. This game can really make you forget about time.. :)

  6. Zupertails said,

    January 8, 2012 at 21:05

    Thank the heavens! A good tutorial on all types of signals and on optimizing your tracks

  7. Sebastiaan said,

    August 24, 2011 at 01:44

    Great site, thanks for your clear explanation!

    Personnaly, I like to have my trains always making their rounds in the same direction (for clarity), whereas in your setup pro-final image, Mardingbury is visited counter-clock-wise, and Lundinghattan ridge clock-wise.

    Removing the single exces piece of track from this image (below the center carriage of the rightmost train) would also help in better visualising train paths.

    Further, I couldn’t understand this part: “The lock runs from the exit -pre-signal at the entrance to the station, to the regular one-way signal at the exit of the station.”

    Would love to see more articles from you! Happy gaming!

  8. Glenn said,

    August 13, 2011 at 04:30

    Hi, thanks for the tutorial on OpenTTD pre-signals.

    I’ve been doing it all wrong for years….lol!

  9. QW said,

    July 18, 2011 at 22:56

    First site I have found to explain the Pre Entry and Exits! Thank you.

  10. Fat Controller said,

    June 12, 2011 at 18:13

    This is a great tutorial on one of the key aspects of station design and network connections; ro-ro layouts with pre-signals and 1-way tracks are definitely the way to go. When I stopped playing OpenTTD for a few years and then came back to it this was the most useful refresher. Things can get a bit complicated when feeding a busy station from lots of different locations but combining the above techniques with expanded clover-leaf junctions should give most people all the options they need. Nice job!

  11. Graham King said,

    May 10, 2011 at 22:08

    @Paul: You’re right, at that point they are not needed, but they will be soon. When a third station is added, picture it off the top left of the screenshot, it will connect to New Frondingworth on it’s loading loop. An almost unlimited number of stations can connect to that loop.

  12. Paul said,

    May 8, 2011 at 06:26

    Why are loops needed in the final screenshot? With one-way tracks connecting the stations, wouldn’t the trains just go from the exit of one station to the entrance of the other? Why do you need tracks going from a station’s exit back to its own entrance? No train would ever take that route, would it?

  13. Arokh said,

    April 13, 2011 at 15:12

    Pleeeease… help me…

    I really want to understand this system, but I don’t. I don’t understand the block-thing, the meaning of all these signals and what is what and at last: the zooming. For me everything is that small on the map, I sometimes don’t even see differences between the signals. Just one more zooming option, ONE…

    I read now 2 or 3 german tutorials about it and now this one. I don’t get it, because I am missing the meaning of the signals.

    Please, write an e-mail to me if anybody is able to explain these things.

    Thanks! Arokh

  14. Pers Greenbourg said,

    November 6, 2010 at 13:52

    I’ve just started playing OpenTTD, and this post really helps coz I’m about to try using signals, but man, now my head hurts after reading this :)

  15. skymonrie said,

    October 5, 2010 at 00:01

    Oh my, Thank you very much!

    This has been a great help and aid to playing Transport Tycoon, I love playing it with trains :3

    I used to play the original way back when I was a little kid coughs shyly and would generally just give trains their completely own track. Now it feels a lot more proper and those idle hours of geekery can roll with smiles, and a proper train network.

    Again, thank you for writing this guide

  16. Dave said,

    September 9, 2010 at 01:48

    Thanks for taking the time to write this, I just couldnt get the hang of all these different signals and had been using basic block signals which are very inefficient I can see now :)

    One point I would make which may seem obvious to most is that you have to drag the one-way signals in the direction you want the train to travel even if you only want one signal (took me ages to figure that out trying to follow your guide on station exit signals)

  17. Korkut said,

    September 8, 2010 at 07:13

    I was trying to figure out pre-signal layout. And this article seems to help me to understand it. Thanks…

  18. Albo said,

    September 6, 2010 at 02:31

    Thanks for the tutorial, specially for the last tip! it’s so true

  19. Simon said,

    July 27, 2010 at 16:06

    it has taken me weeks to fully figure out the openTTD train signals. This just added to that knowledge. Thanks.

  20. Alexander Enge said,

    July 8, 2010 at 20:12

    g8 tutorial! I’ve ridden so many articles about signals in OpenTTD but this is the first one I understand!

  21. Daire said,

    July 7, 2010 at 16:31

    that didnt help me at all it all failed and im unhappy about that so why is it not working?????!!!!!!!

  22. EVADNELLA said,

    May 15, 2010 at 05:39

    I was playing TTD (Not yet OpenTTD) since 1998, I just only knew how to use that “ONE WAY” signal, I discovered already a lot of track combos without using one way signal, but now I’ve just learned from this tips. Thank you…

  23. Mikkel Roosevelt Hertz said,

    March 15, 2010 at 00:51

    I’ve been playing Openttd now for about a year or so, and i still don’t fully understand how to utillize the signals and pre-signals in order to gain fully control of a situation. The only thing to do if you want to fully master Openttd is to play, play, and play until you get it.

  24. Betsumei said,

    February 17, 2010 at 19:01

    Can’t wait to put this into practice! Nice!

  25. Lars said,

    November 17, 2009 at 18:57

    Great tutorial! Especially for people like me who ran exactly into the beginner problems you describe here. Even after delving into the OpenTTD WIKI it wasn’t really clear for me (hey, no offense – the WIKI is great as well! ;-)). Especially your highlighting in the images (red, yellow, etc. segments) makes the whole A LOT clearer.

    Thanks again! Great work!! And yep, I already figured out what you meant by saying ‘Playing with virtual toy trains can be quite addictive, so remember to get some sleep’ %-)

    Cheers, Lars

  26. Babant said,

    November 15, 2009 at 23:20

    Oh yes, the last tip is the most important one! Just yesterday, I was playing OpenTTD “just for a while”, when I realized it was 6 o’clock in the morning. 8-)

  27. klaus said,

    November 15, 2009 at 18:49

    Thank you for this tutorial; the pre-signals really helped me.

  28. Phil said,

    June 26, 2009 at 10:58

    Interesting points raised as I have only just twigged the concept of one-way signals – large layout mostly double track – but of course double-tracks and two way signals just means that trains run two way over both tracks – hold-ups and congestion are the norm! So bit of re-design for me! However can you tell me how to best set up signals for a proper terminus set-up? Sometimes there just isn’t enough space to construct exit loops (and it seems to me that an exit loop can be quite wasteful space-wise if you have many platforms).

    Regards

Leave a Comment

Note: Your comment will only appear on the site once I approve it manually. This can take a day or two. Thanks for taking the time to comment.