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# Rail signal

Rail signals are used for automated transportation on a railway network. With rail signals it is possible to use multiple trains on a single track.

## Usage

A south-bound train line branching off in three directions. Each rail signal (highlighted red) divides the track into a new block (various colors).
• Place a Rail signal at the right side of a segment.
• Imagine this signal as a "cut" into the rails which splits the segments before and after this signal in two "blocks".
• If a train stands in any part of a block, the signal before this block is red.
• No other element can do this cut, which means, that all switches, crossings and so on are part of this block.

Pictures say more than thousands words: A guide on how to place signals.

## The model railway understanding

Imagine that block signals works like in a model railway. The basics of this principle is as follows:

• The rails (left and right) can conduct electrical current (they are made out of steel).
• The train connects the left and right rail of a railway and works so as a conductor between the left and right rail.
• The signal puts a small current into one rail.
• If the train stands on the rail this voltage is also on the other rail. There is a connection between left and right rail.
• Can also be imagined that a small amount of electricity flows.
• The signal knows then: "Train on my block" and the signal goes red.

Now again to the definition of a block and segment:

• Segment: a single path of continuous track, a track between intersections or switches. You can see the number of the current segment when hovering the segment.
• Block: a set of segments (or one segment). Every connected segment belongs to one block, no matter if a train can drive on it or not, and no matter, if it can be driven only in one direction (for example a joining switch: the other segment of the switch belongs to the same block!). You can see the current block numbers of a rail piece in the info section.

Going back to the model railway example, this means:

• Every signal makes a "cut" into the rails.
• This cut splits one segment into two.
• And this stops also the electricity from flowing from block to block. In other words: Only segments inside a block are "connected". The electricity can flow into every segment of the block, but not in any other segment/block.
• This is also true, even if the train could not reach this segment, because it is in the wrong direction!

In other words: If there is no signal, then the segments are connected. Only signals split that connection!

## Other mechanics

### Yellow lamp

The signal looks into it's forward direction (the next block). If there is a connection (a train on it!) then it switches to red.

This is how it switches to yellow:

• The train needs some distance to stop. You can see this distance by going into the Debug mode and turn on "show_train_stop_point". You see: With increasing speed, this distance gets longer.
• All signals in the direction of the train path within this distance are switches to yellow (first come, first serve)
• Yellow signals "connect" the two sides of the track, exactly like, if there is a train on it.
• That switches all other incoming signals into that block to red...

### Pass-by stations

• To enable more traffic on a long single-track, you need to create pass-by stations: Split the one-way track into a two-way track for the minimum length of the longest train. One way signals route the trains on one track per direction. For each track one-way-signals must be placed at the begin and end of each of the two pass-by-tracks.
• If you have enough pass-by-stations, you can connect them and have a two-way-track.
• Don't forget to leave a space of one track (~2 tiles) between parallel tracks. This will allow merging the tracks together if necessary.

### Circuit control

The circuit network can be used to control switches, by disabling and enabling them. Trains will not pass through a disabled signal.