OpenTTD junctions

Years ago, long before the likes of Rollercoaster Tycoon came on the scene, Chris Sawyer released Transport Tycoon for the PC, a DOS-based game working on an isometric grid where the player created complex transport networks between industries and towns.  Over a decade later and the game has been ported to other platforms, developed almost beyond recognition, and has a cult following of enthusiasts still hooked by the thrill of the money-spinning construction game.

Having recently installed the Mac version of OpenTTD (which is the open-source release of Transport Tycoon Deluxe) I have been reliving my wasted youth building expansive rail networks with complex junctions and sprawling airports.  But rather than quietly indulge in my own private geekiness I opted to share my obsession with the world.  Here, then, are some screenshots of some junctions I have just built for demonstration purposes.

A basic station setup

This is pretty much as simple as you can get.  A two-way railway line (one in, one out) ending in a small terminus station.  Not particularly efficient if you have a lot of traffic, since trains leaving stop trains coming in, and vice versa.  Things are made slightly more clever by the use of those colour-coded signals: the signal with the yellow horizontal bar only shows green if at least one of the signals after it with the white vertical bar is green.  This means that if the station is full the first signal will still show red, even though there is no train on the next piece of track.  Cunning, eh?

Basic station

One-way station

This is often referred to as a RoRo station (Roll On, Roll Off), and the basic idea is that trains enter the station at one end and exit at the other, which solves the problem of trains holding each other up.  With the signalling doing its work you can extend the station almost indefinitely and it will still work, although if you are planning on having stations with 100 platforms then you’ll probably want a more sophisticated approach to let more than one train come in at once!

One-way station

Three-stage station signals

This concept takes the basic RoRo idea and puts a little more control in place.  Here, we make use of the third special signal state, which is a combination of the two first ones.  The signals effectively split the station up into sections, so when one fills up trains will fill up the next section.  In this example it’s all rather scaled-down so there is no real benefit, other than in looking more interesting, but when the station gets enormous this system could bring some benefits in allowing multiple trains to come in at once.

Three-stage station signals

Offline station

Terminus stations are inefficient, but the above solution is only good for stations at the end of a line.  Sure you could put in a junction (see below) so it effectively is at the end of a line, but this solution allows you to have trains entering a RoRo station from either direction, and exiting onto either side of the track afterwards too.  Traditionally we would use a half cloverleaf approach (which I’ll talk about later), but this is a simpler solution that works almost as well.  If you’re in a hurry to build an offline station this is probably the quickest way of linking it all up.

Offline station

Compact offline station

This is just a squashed up version of the above layout, but with the trains coming into the station from the other end to make the junction a little more compact.  This is no good for busy stations as trains will get backed up onto the main line and snarl things up big time, but for a low-use station in a tight spot this could come in handy.  And no horrible right-angle bends either!

Compact offline station

Compact 4-leaf clover junction

This is the classic 4-way junction, a tried and tested intersection that is even used in real-life.  Ideally this should be a little more spaced out to ensure that trains waiting at signals don’t hold up the main lines, but if you’re pushed for space then this is the smallest you can realistically get it.  Some people swear by it, and for the most part so do I.  My main gripe is that trains have to double back on themselves, turning a full 270 degrees and going completely the wrong way for a moment.  For the most part trains don’t get too confused about this, but it still strikes me as a less-than-ideal concept, hence my next few examples.

Compact 4-leaf clover junction

Reversing 3-way junction

This is a very simple 3-way junction that is both compact and efficient.  The only problem with it is that left and right tracks reverse themselves in the process, and while this isn’t a huge problem in itself it does present problems when it comes to connecting to other parts of the track.  Generally speaking you want to keep your left and right tracks consistent; I usually put the signals on the outside of the track all the way through, but as you can see in this picture the signals have switched to the inside with this junction.  Easily solved, I know, and if that track is only going to a station it makes little difference.

Reversing 3-way junction

Reversing 4-way junction

Taking the above concept further is a little more complicated, but it can be done.  The underlying idea is that trains shouldn’t double back on themselves as with the cloverleaf layout.  For the most part I like this, except for the fact that the tracks reverse sides in the middle, hence the need for the reversers at each end to put the orientation right again.  Not particularly tidy as a result, but it works.

Reversing 4-way junction

‘Superman’ spiral 4-way junction

I called this the ‘Superman’ junction because the track spells out an ‘S’ in the middle that looks a little like the logo on the Man of Steel’s chest…  Anyway, that aside, this is a fairly good junction that involves no doubling back, and should cope with a fair amount of traffic too with long connecting lines.

Spiral 4-way junction

Interlocking half-cloverleaf 5-way junction

This is an example of how to achieve a 5-way junction, something that isn’t normally attempted because of the restrictions of the isometric nature of the game.  Rather than trying to bring all 5 main lines to one central point they connect to one main line in an interconnected chain of half-cloverleaf junctions.  It’s a little compacted, and it would have been nicer to give those connections a little more length so that trains wouldn’t hold each other up, but generally speaking it works very well.  It also looks pretty cool.

Interlocking 5-way junction

4-track half-cloverleaf juntion

For those really big networks where you have two tracks going in either direction, expanding junctions is a little more complex, but still achievable.  Here is an example of a traditional half-cloverleaf junction expanded out to cater for four lines instead of two.  Again it’s a little bunched up and a little more space between signals would be preferable, but this design works and allows for lots of traffic.

4-track half-cloverleaf junction

8 to 4 track merge

There may well be times when what you really want is to merge two large backbones together into one, and this is a neat and tidy solution that keeps traffic moving with minimum hold-up.  And again, it looks cool.

4-track merge

5 thoughts on “OpenTTD junctions

  1. Matthew, you play WAY too much TTD… on the other hand, do you have any idea where I could get a copy of the TTD data files? I don’t know if you can even still buy it 🙁 I remember having the game on my computer a few years ago but when I scrapped my old Windoze installation I must have lost it!

  2. I downloaded them from somewhere a while ago, can’t remember for the life of me where from, but Google it and I’m sure you’ll find it eventually! To run OpenTTD you only need the data files from the Windows version, you don’t need to install the Windows version though.

    I have to admit, the game is pretty addictive. I don’t remember playing it for long periods of time, it’s only afterwards when hours have passed without me noticing that I realise the grip it has on me…

  3. Pingback: » Blog Archive » Eating ham and jam and spamalot…

  4. If any of your visitors are looking for the TTD files, I found and downloaded a working copy from The files work without a problem and the site master has a team of game coders constantly updating the software.
    Hope this helps and there are tips on the site to help during version selection and download.

Leave a Reply

Your email address will not be published. Required fields are marked *