OpenTTD Signals explained - a guide

One of the greatest features of Transport Tycoon Deluxe and OpenTTD is the ability to create sophisticated railroad systems. In order to do so, one has to make use of the available signals. Especially with the 6 different signals available in OpenTTD, this can seem very challenging. But don't worry, I'll run you through all of them. In case you are playing OpenTTD, my advice is to stick to the newer path signals for now.

Note that this article is more of a reference or guide rather than a tutorial. It thoroughly explains the way signals work so that you should be able to come up with solutions for any scenario. For usage examples, like common station or junction setups, see the additional links provided.

Prerequisites for building signals

In case the signal selection toolbar doesn't show up, it needs to be activated:

Advanced settings » Construction » Signals » Enable the signal GUI

Basics of building signals

Signals overview

It all started with the block signals. While the block signal itself was already available in Transport Tycoon, the entry, exit and combo-signals were introduced with OpenTTD version 0.2.

Today, the relevance of the block signals decreases as most of their functionality can also be achieved with the new path signals.

The path signals follow a different concept and were first introduced with OpenTTD version 0.7. They provide some great advantages over the block signals. In addition, they are easier to use.

Signal blocks

Signal block: straight trackSignal block: branched track


Block signals

possibilities of passing block signals

Block signal

An occupied signal block results in a red block signalTwo occupied and two free signal blicks

Entry and exit signal

Although the signal block is free, the entry pre-signals are red because all exit-signals are red

Since all following exit signals are red, the entry pre-signal won't let the train from the bottom right pass - even though the signal block (marked blue) is free.

Important: the entry pre-signals don't consider the route of the train. Therefore, they'll also show green when the exit signal on the left or in the middle changes to green - although it's impossible for the train to get there.

Combo signal

Although the signal block is free, the entry and combo signals are red because all exit-signals are red

The block signal is green because the following signal block (marked blue) is free. It doesn't take care of the exit signals.

The combo signal is red since both of the following exit signals are red.

The entry signal is red since the following exit signal, as well as the following combo signal, are red.

Path signals

Possibilities of passing path signals

Thanks to path signals, two trains are passing the same signal block at the same time

Although there's already one train inside the following signal block, the second train can pass the one-way path signal because it can reserve a free path through the signal block.

The darkened tracks indicate the reserved paths. This feature is deactivated by default but can be activated manually:

Advanced Settings » Interface » Display options » Show reserved tracks

A train reserves his path, ignoring the reverse side path signal

The train from the bottom left reserves its path through the signal block. For it, the signal block doesn't end at the following reverse side path signals.

In the opposite direction, two trains wait for a free path. The track at the bottom/right is no option, since the one-way path signal up ahead can't be passed from behind.


Note: I disabled the comment function because of spam.

2012-04-18, 08:23:07

The entry pre-signal "shares" the characteristics

Nick J Boragina
2011-08-08, 05:21:36

ENGLISH (since you asked) --- With the signal tool selected, the signal selection toolbar shows up. - This sounds a bit weird. Perhaps "When the signal tool is selected, the signal selection toolbar will show up" or "With the signal tool selected, the signal selection toolbar can be used" --- "A signal block is also closed by a depot or at the end of a track." - a comma would make this a bit easier to read (an "oxford comma") example: "A signal block is also closed by a depot, or at the end of a track." --- "Combined with different signals, the last named of this list will be used to decide about the embedded signal." - the words "used to decide about the" sound odd together. I'm not 100% sure what is better, perhaps "used to dictate the" or "copied in the" --- "Solely combined with block signals, the combo signal will behave like a block signal." - the word "Solely" is rare in use. "When combined with" could work but might be confusing, "When combined with only" --- "Both path signals can be build heading one direction (A or B)." - "can be built" as build is to do and built has been done. can be done, not can be do, if that makes sense. --- that's all I can find!

Nick J Boragina
2011-08-08, 04:49:00

Wow!!! This is amazing. The pictures are what sold it. The wiki was just far too much to digest at one time, especially when you don't understand what they are talking about. Once I figured out what was going on in each picture, I finally understand what the hell these signals do - and thus, I can finally understand what the wiki was babbling on about. --- Do you mind if I add these to the wiki in some way?

Anuj More
2011-05-20, 09:18:44

Very nice. However I ended up on wiki.

This is good for starters. Refer to wiki for more :)

2010-12-17, 18:21:59

This description on how signal blocks work is probably one if not the best one out there. Also on how to cycle through signals is very well illustrated. Mind to add these pieces of information to the official wiki?

2010-12-13, 12:40:07

The Path-signal is not 100% explained, but this is a good starter tutorial

2010-11-25, 17:34:14

Since I'm not a native English speaker, there might be some mistakes in the above tutorial. Please feel free to leave a comment, if you can provide any corrections.