Switches and Crossings are devices that allow trains to travel from one track to another or cross another track. Only one train can be on one such device; if you have two you have a collision at hand. Crossings on separated levels (flyovers, pass overs via bridges or tunnels) are not covered here – a track passing under another track is just broken up on the diagram (the approaching parts can be still in one block), there is no special symbol for this.
Simple switches have connection to three other track objects, which can be another switch, crossing, block, or a control point having signals, while crossings and slip switches have four of them.
All devices except simple crossings can be “turned”, that is, the active path the train can travel in either direction can be changed. While turning a switch, the symbol will flash, simulating the time needed to turn the switch and get a response back confirming successful execution from the point machine. Simple switches have one such machine, while slip switches have two of them (slip switches with one point machine moving all points at once are not supported in CTC). These machines can be locked, either by the user (preventing them to turn the switch unintentionally), or by a route, locking the switch in position while a train is traveling on it. Locking can also occur for protection of nearby routes.
The following colors are used to indicate the occupancy status of a switch or crossing (active path only)
- White – normal status, unoccupied, not part of a route
- Green – part of a route, but not occupied
- Red – switch or crossing is occupied by a train
The inactive path of a switch is shown in dark brown. If a switch is locked, the inactive path is replaced with a line indicating a disconnect from the active pass (orange if route-locked, magenta if user-locked or both). Inactive paths in simple crossings are shown in white.
The white color is replaced with gray during route setting.