"Network Rail estimated in October 2012 that it would be spending £461 million on upgrades to the Great Western and East Coast Main Lines as part of the Inter City Express Programme. Much of this cost refers to power supply upgrades to the East Coast Main Line, with a smaller amount needed for platform extensions to accommodate the longer trains and an even smaller amount required for gauging work."
I am surprised at the low cost. It suggests that Network Rail are taking a more relaxed view of gauging than they were about fifteen years ago. This is likely to be because of increased control of the infrastructure which has made it possible to reduce tolerances. That there had been a degree of double counting of tolerances was explained in a lecture to IMechE by Bill Reeve when he was in charge of improving clearances for freight. Part of the freight gauge clearance programme was achieved by applying the principle.
I am sorry if people felt offended but it is a pity that nobody actually managed to shed any real light on the subject.
Whether it would have been better to fill up the extra space with wider vehicles rather than longer ones is another question.
