The viability of running 'super high-speed' trains on the proposed HS2 line has been called into question by a professor who has been paid to investigate the issue.
Prof Peter Woodward, of Heriot-Watt University in Edinburgh, said plans to make HS2 the fastest railway in the world with speeds in excess of 225mph could cause "rapid deterioration of the track, ballast and sub-ballast, including possible derailment and ground failure".
He also told The Engineer magazine: "It is possible that, if the train was allowed to run at this critical track velocity, it would derail at high speed."
Meanwhile Transport secretary Justine Greening has revealed in an answer to a parliamentary question that £25.8million has already been spent by her department on consultancy fees for the HS2 project.
Of this, Arup has taken the biggest slice of £7m for its work on assisting with the design of the route, £4.4m has been paid to Mott Macdonald for engineering services and £3.5m to Booz and Company for environmental and economic services.