Test Coach 'Mercury' (aka Lab 18)
Prior to being incorporated into the Structure Gauging
Train, RDB975280 Test Coach Mercury had been used in the late 1970's to monitor the
transponders then being fitted to the WCML in connection with the introduction
of the C-APT track-to-train communication system for the Advanced Passenger
Train. This was a new development at the time and the benefit of a transponder is that it does not need a power supply and is 'interrogated' by a device on the train as it passes. The same principle is used today for the TASS system on the Voyagers and Pendolinos. R&DD was pioneering the system in the UK 30 odd years ago. |