Train drivers are being paid an extra £1,000 a year for operating at 140mph on the West Coast Main Line, even though the speed will not be reached until 2013 at the earliest.

Under a hopelessly optimistic plan by Railtrack, services should have been travelling at 140mph by May 2005, but yesterday it was revealed that new "tilting" trains will be limited to 125mph for at least 10 years.

The pay deal putting 500 drivers on £34,500 a year was struck by Virgin Rail, which is receiving considerable support from taxpayers because of delays to the modernisation of the London to Glasgow route.

Richard Bowker, chairman of the state-financed Strategic Rail Authority (SRA), yesterday said he would be negotiating with Virgin on the future of the franchise. The SRA is already paying at least £106m in compensation to Virgin for delays to the project.

Announcing a £10bn plan to complete the project – the original Railtrack scheme cost £2.5bn – Mr Bowker said there was a risk of trying to be "too clever too fast".

He confirmed he would have to ask for more Government funding for the project.

Alistair Darling, Secretary of State for Transport, welcomed the SRA's approach, adding that Railtrack had "grossly underestimated" the plan's costs.