Building signals
From OpenTTD
More walkthroughs:
- Railway tutorials
- Building tracks
- Building depots
- Placing signals
- Building stations
- Buying & selling trains
- Setting vehicle orders
- Building bridges
- Tunnels
- Landscaping
- Replacing vehicles
Signals (normal signals and pre-signals) are all designed for one purpose - effectively directing your trains, stopping them from crashing and taking correct routes and railways.
This tutorial shows you how to build (place, change), re-design (change type of) and remove (delete) your signals. Demonstrates what signal types there are and how they are used. Pre-signals (entrance/entry, exit and combo) are described in detail with examples.
Contents |
[edit] How do I build signals?
First of all, you must open the Railway construction toolbar - click the railway build button ( 
) on the menu bar to display the railway construction toolbar:
Whatever signals you are building, you start off by placing normal signals. So read the 'How do I build normal signals' first if you are unfamiliar with the whole signal concept.
[edit] How do I build normal signals?
1. First, select the Place Signals ( 
) button from the construction menu:
2. Next, position your cursor over the railway tracks, where you wish to build your signal.
3. Click once to place a signal on that piece of tracks. You will build a two-way signal - green or red lights will be shown to trains coming both ways.
4. Click again to re-design the newly built signal to a one-way signal. Now only the trains coming from the signal light side will be able to pass it. (Trains that are lost and coming from the other way will have to turn around).
5. Click again to re-design the signal again to face the other way than before.
6. Click again and you will revert back to your two-way signal.
[edit] How do I build a signal line?
You can also build several signals of the same type at once, by dragging from an existing signal along a railway. This works for normal two-way or one-way signals. If you try to drag from a pre-signal this way, you will result having built normal signals facing the same direction. This is also sometimes useful.
1. While Place Signal tool is selected, position your cursor over an existing signal.
2. Click and drag the mouse along the railway track.
3. Release the mouse to place the signals.
Depending of your patch settings (default is 4), signals will be placed every N game tiles.
[edit] How do I build pre-signals?
Building pre-signals is very much alike re-designing signals with the exception that you must hold the Ctrl button down. Once you know how to build pre-signals, you can read below to understand the way they work.
1. Position your cursor over an existing signal (it doesn't matter whether it is one-way or two-way signal). Hold down Ctrl and click to change the signal to an entrance pre-signal.
2. Hold Ctrl and click again to change the signal to an Exit pre-signal.
3. Hold Ctrl and click the signal one more time to change the signal to the last pre-signal type - Combo pre-signal.
[edit] Notes
- You can always change your pre-signals to one-way pre-signals by clicking them with Place Signals tool without holding down Ctrl.
- It does not matter if you build one-way signals first and then change them to pre-signals or build pre-signals first and then change them to one-way.
- You cannot click and drag pre-signals (why would you want to anyway?). However, clicking and dragging from a pre-signal will create normal signals facing the same direction instead.
- You can now make pre-signals easily using the signal GUI.
[edit] How do I remove signals?
To remove signals, select the Remove tool ( 
). The white square will change to a red square. Now you can simply click the signals to remove them. Click the tool button again to deselect it. You can also use the R key shortcut.
1. Position your cursor over the signal with the Clear button ( ).
2. Click the signal to remove it.
You can also click and hold an existing signal and drag along the track (similar to placing signals) to remove previously placed signals.
Note: This will not remove every signal, only every Nth signal (depending on your patch settings) along the track.
[edit] What do signals do?
[edit] Normal signals
Trains would run on the tracks crashing into other trains if not for the signals. Signals don't let your trains pass if there is something behind the signal blocking their path. The signal controls the track block (continuous railway /bridge, tunnel, station platform/ behind it until the next signal) behind it.
Normally, all signals show green lights as there is nothing blocking the way for trains. Trains pass green lights without slowing down or other interruptions.
If there is something in the way (which almost always happens to be another train), the signal will show red. The trains will stop just before the signal to wait until it clears to green.
A two-way signal acts as two independent one-way signals, checking and showing the state of tracks in both directions.
It does not matter if there is some other free route a train could go or the train now occupying the route would never even run close to incoming train, the signal will stay red.
Note: If trains are waiting at a red light and nothing happens for a while, trains will turn around to try to find another route, which is usually a futile effort.
[edit] Pre-signals
The pre-signals don't let your trains go forward if there is nowhere to go right now - all the signals afterwards are red lights. You can proceed on reading the full description of signals, however, see the example below to understand what the benefits of using the pre-signals are.
[edit] A valuable example
For example, you might have a Ro-Ro station (1 side - entrance; other side - exit).
This is how you would place the normal signals for this station.
If two trains arrive at the station, both station platforms will be unaccessible and both station platform entry signals will be showing red lights. This however does not prevent the first signal to show green, since there are no obstacles on the tracks between the first signal and second signal line.
So what happens when the next train arrives? It simply passes the first green light and then has to choose a path which will be blocked anyway. It might work fine for some cases, but what if the train on the other platform leaves first? The new train will still have to wait.
Here come the pre-signals. Once correctly positioned, the first signal light will also stay red as long as all the other signal lights are red and the new train has nowhere to go.
This way, when a track clears, the new train can proceed to that track.
For more information on Pre-signals see Signals
