When the path includes a train stop -> Add a penalty of 2000.

When the rail block is guarded by a rail signal set to red by the circuit network -> Add a penalty of 1000.

When the rail block is occupied by a train -> Add a penalty of 2 * length of the block divided by block distance from the start, so the far away occupied paths don't matter much.

Base cost for a block/segment is the length of the segment (linear grid length along the center of the rail).

The cost (distance) is calculated using the following weighting rules: A segment is an uninterrupted plain sequence of rails, with no intersections, stops, or signals (all of which define segment borders).

3.2 Repaths that happen as part of normal train operationįor calculation it uses a simple A*-algorithm : The pathfinder first builds a list of non-disabled stops that match the name in the schedule, then searches outward from both ends of the train at once, if applicable, in segments.

Rail chain signals can be read by the circuit network.

With chain signals, this problem can be totally avoided by preventing the train from going to the shared section unless it can exit it. Here a train can't enter the line because another train is in it, but that train in turn can't leave the line.

With chain signals, the rails that don't cross are still separated, but trains won't stop in the middle of the crossing.Īnother common cause of blockages are bidirectional single track lines with occasional bypasses. It can even cause total deadlock, which require manual intervention to fix the problem.

The chain signal prevents the train from blocking the crossing route while waiting.ĭouble crossings are a common cause of train jams, as trains can stop in the middle of the crossing and block everything. With a regular signal, the block after it is empty, so the train can go there.Ĭhain signal with one exit doesn't allow the train to enter the block, since it can't leave immediately.

Regular signal compared to a chain signal If it is blinking, it is not on a rail, or unable to divide it into separate blocks.In this case trains may or may not stop, depending on their path. If it switches to blue, some but not all exits are free.If it switches to red, all exits are occupied.If it switches to yellow, the block is reserved for a train and all other entrance signals of that block turn red.If a chain signal switches to green, all exits are free.If there are several chain signals before a regular one, a train waits before the first chain signal if the block after the regular signal is occupied.Since trains react to chain signals based on their own path, chain signals before a crossing will not stop trains if the other track's exit is blocked.If the chain signal has only one exit, it doesn't allow the train to enter its block, if the train would have to stop in said block.When more than one exits exist, the one where the train is pathing to is considered. In effect, this prevents a train from entering a block if it won't be able to leave. However, a chain signal also looks ahead to the next signal, and turns red if the next signal is red. If automated trains are required to drive in both directions on the same track segment, signals need to be added on both sides of the track, opposite each other.īoth normal signals and chain signals prevent a train from entering the next block if it is obstructed. Rail chain signals are placed like regular signals at the right side of the railway track.The best prerequisite to understand chain signals is to understand signal blocks.

Factorio train