diff --git a/src/signal_func.h b/src/signal_func.h
--- a/src/signal_func.h
+++ b/src/signal_func.h
@@ -43,5 +43,8 @@ static inline byte SignalOnTrack(Track t
 
 bool UpdateSignalsOnSegment(TileIndex tile, DiagDirection side, Owner owner);
 void SetSignalsOnBothDir(TileIndex tile, Track track, Owner owner);
+void AddTrackToSignalBuffer(TileIndex tile, Track track, Owner owner);
+void AddSideToSignalBuffer(TileIndex tile, DiagDirection side, Owner owner);
+void UpdateSignalsInBuffer();
 
 #endif /* SIGNAL_FUNC_H */