Similar self-operating point mechanisms have been replaced by machines on the Central Wales Line under NSTR. The idea of the replacement technology is that a local interlocking is established for the passing loop. This 'listens in' to the RETB radio traffic or receives equivalent triggers from the traditional token machines in Wales and sets appropriate routes through the loop end turnouts according to the position and direction required. Full track circuit (or axle counter) controls for dead locking and approach locking timeouts etc are provided through each loop end junction so standard point machines can be relied on to move safely for the passage of each train (and most importantly not to move unexpectedly under a train!).they're also now obsolete and there are limited spares so new installations are unlikely. I believe there is a project ongoing in Scotland to remove them by linking the RETB tokens to point machines.