anuran

Also, "A prototype of the HST, the British Rail Class 43 (HST) achieved 143 mph on the line in 1973[4] before current UK legislation requires in-cab signalling for speeds of over 125 mph which prevents the InterCity 225 train-sets from operating at the Class 91 design speed of 140 mph (225 km/h) in normal service. Before the present in-cab regulations came in, British Rail experimented with 140 mph running by introducing a fifth, flashing green signalling aspect on track between New England North and Stoke Tunnel. The fifth aspect is not observable in normal service and appears when the next signal is a flashing green aspect and the signal section is clear which ensures that there is sufficient braking distance to bring a train to a stand from 140 mph"


Wow. I love non-computer related geekery.