RailwayContainer ::= Route* Region*;

abstract RailwayElement ::= <id:int>;
Region : RailwayElement ::= TrackElement* Sensor*;
Semaphore : RailwayElement ::= <Signal:Signal>;
Route : RailwayElement ::= <Active:boolean> SwitchPosition*;
SwitchPosition : RailwayElement ::= <Position:Position>;
Sensor : RailwayElement;

abstract TrackElement : RailwayElement;
Segment : TrackElement ::= <Length:int> Semaphore*;
Switch : TrackElement ::= <CurrentPosition:Position>;

rel Route.requires* -> Sensor;
rel Route.entry? -> Semaphore;
rel Route.exit? -> Semaphore;
rel Sensor.monitors* <-> TrackElement.monitoredBy*;
rel TrackElement.connectsTo* -> TrackElement;
rel SwitchPosition.target <-> Switch.positions*;