Proprietary train braking system by the Westinghouse Co. of the UK using a 7-step relay valve on each vehicle controlled by three train wires. It has a digital control system, with an additional round-the-train-wire designed to replace the brake pipe and energised-to-release control wires to give electro-pneumatic brake control. The control is fail-safe by causing an emergency brake application upon loss of signal on the train wires or loss of their electrical supply.