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→Purpose
(Edit by Karlos aka ixiik: For simple text is not needed any tag)
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===Purpose===
A signal divides a railway line into two sections known as ''blocks''. If a block is occupied by a train then the signal dividing these blocks won't allow any other train to enter that occupied block until this block is cleared.
There are currently two kinds of signals:
* block signals
* chain signals
===Placing of signals===
* one (the first) left mouse button click = two way signal will be placed on a railway track <br>* two (a second ) left mouse button click on the same signal = two way signal will be transformed to one way signal <br>(You decide which way a one-way signal will orientate by which side of the track we clicked on will determine you click. Yes, this might at first come across as slightly difficult, but zoom in and you'll soon get the orientation hang of the it. The game defaults to automatically selecting which type of signal to place, as well as defaulting to two-way signals. You can change to manual selection as well as one-click one way signals in [[Game Settings]]. There is a multi-signaltool which lets you place several signals evenly spaced out. Convenient on longer stretches of track! (The tool even lets you change the spacing - if you want a signal every four squares, or five, or eight... Each signal costs a small amount of money)
Signals cannot be placed at station platforms and directly on railway intersections. Signals are hard to place in tunnels, but you can get around this by using the multi-signal tool: it will space signals correctly to allow for efficient use of longer tunnels. (It is admittedly hard to delete those signals without deleting the whole expensive tunnel though)
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==Block signals explained==
[[File:Signal.png|200px|thumb|left|A Block Signal in Realistic View]]
Block signals allows access only on the blocks which are not occupied by other train. Block is the space of railway between two signals. You can see the block status with the arrows pointing towards the segments. Red arrow means that the block in the arrow direction is occupied.<br>
===Block signals basics===
[[File:Simple-avoidance-fin.png|thumb|350px|right|station Station with two one track and twoone-way signals. Please click the image to zoom in enough to view the little green arrows]]
On the right picture you can see our example station situation. Each block is located between two signals / end of the track and colored with different color. Red is the station block, blue is the entry block, yellow is the exit block, and green is the rest of the track. Yellow track is the exit from station. This way, one train can approach the station from the left while another train can leave from the station.<br>
You can notice that the station block is now split into two tracks with two one-way singal. One "entrance" signal, one "exit" signal. The incoming train will enter from the green block to blue block. Then the train enters the station, the red block. Next incoming train will have red sign on the entrance signal, because of occupied red block and it will wait in the blue block, while the first train will have space to leave through the yellow block. This is effective enough on the low load railroads.
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===Common mistakes===
===Correct signals===
Here are a couple of correctly configured signals, where "correctly" means that trains that just run past each other won't stop/block each other. (Obviously if a train needs to switch tracks other trains are stopped)
{| class="wikitable"
! Image
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For more examples of intersections, see [[Junctions]] page.
===Correct use of bi-directional signals===
To prevent trains from getting stuck nose-to-nose at bi-directional signals, they have to be placed very carefully. There are basically only two situations where they should be used:
==Chain signals explained==
===Definition===
''Chain signal will be green if there is at least one green signal behind it.'' <br>
There are three main situations where chain signals are needed:<br>
* ''At crossings'' to prevent train from blocking the crossing, if the train cannot continue beyond it. Correctly placed signals are '''Chain before''' the crossing and '''Block after''' the crossing. If the track after the crossing is empty -> the block signal is green -> the chain signal before the crossing is green. If the block after the crossing is occupied -> the block signal is red -> the chain signal before the crossing is red as well so next train won't enter the crossing thus it will not block the traffic on the other track. For instance, imagine the upper left track leading to an off-screen loading station, and the first train is waiting its turn. The second train will not enter the crossing (and block it) while it waits behind the first train, thanks to the chain signal.
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[[file:Chain_at_crossing.png|315px]]
[[file:Chain_at_crossing_red.png|300px]]
Just about the only usage is esthetic: Real life railways create blocks of track over multiple signals (such as when a train is to cross multiple tracks such as at yard entrances and exits), and you could try experimenting chaining chain signals to mimic this appearance. In effect, chain signals allow you to place "redundant" signals in complex crossings since a chain of chain signals effectively act as a single block.
== Ignoring signals ==
Trains will never run a red signal by themselves. The only crashes that can happen on a correctly configured network is rail/road crashes, simply because trains can move much faster than road vehicles.
Trains can deadlock, however, sometimes in big jumbling messes. While this suggests a less than optimal signaling regimen has been used, before you can fix the mess you need the trains to untangle. Tools you might find useful in these situations are the buttons in a train's window for reversing trains and instructing trains to ignore the next signal (sometimes in combination). Obviously you need to carefully manually supervise the train's passage because when a red signal is ignored, a crash can very well occur.
Do remember that only the very next signal is ignored. You might have to press the button more than once if the red signal you need the train to pass by is several signals ahead.
[[Category:Infrastructure]]
[[Category:Railways]]
[[Category:Signals]]
