The design specifically includes features for safety, reliability and appearance. In place of cardan shaft drives to the wheels, coupling rods were used to give people something to watch and engine covers were omitted to give a good view of the Rolls-Royce diesel engines. The full-length canopy above the engine covers not only adds to the distinctive outline but also supports the exhaust silencer. For added safety with only one man in the cab, a dead-man device is included, a pedal that when released triggers the braking system to bring the train safely to a halt. The turbocharged six-cylinder engine is rated at and drives through a hydraulic transmission that has only one drive ratio. The result is a locomotive that accelerates quickly up to speed. All four locomotives were rebuilt in 2012–13 in readiness for the launch of the new "traditional diesel" service.