Railway/Train path finding

< Railway | Train path finding

Before a train moves to a target (In this case, a Train stop), it calculates the best route based on the railway network at that time.

For calculation it uses a simple A*-algorithm, with the following special weighting-rules (see the posted path-finding code):

• 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.
• When the rail block is guarded by a rail signal set to red by the circuit network -> Add a penalty of 1000.
• When there is a train waiting in the station -> Add a penalty of 6 tiles per every remaining second in the station. (This also helps the train to choose the best station to queue up for even when all of them are occupied, it picks the one with least time remaining).
• When the path includes a train stop that is not the destination -> Add a penalty of 2000.

The route is recalculated if the train needs to stop. There is an invisible front point internally called the train_stop_point which is used to determine if the train needs to stop. See Debug mode and turn show_train_stop_point on to see that point. The route also recalculated after a train has stopped on a signal. This is to make pathing as dynamic as possible.

History

• 0.15.0:
  • Train station adds 2000 tiles penalty when path finding, so trains try to avoid stations not related to their path.

• 0.11.17:
  • Increased the pathing penalty for non-moving train in manual mode from 200 to 1000.

• 0.11.13:
  • Stopped, manually controlled train adds additional penalty (related to train path finding) of 200 tiles to the block it occupies.

• 0.11.11:
  • The pathfinding is based on penalties for blocked segments now. For trains waiting in station, the more remaining time in the station, the bigger penalty.

See also

• Train pathfinding as of version 0.16 (Code)
• FFF #68
• bug ticket
• Bug ticket explained