Rail upgrade 'too ambitious' says Network Rail
The government says it will delay or cut back a number of modernisation projects planned for Network Rail.
Transport Secretary Patrick McLaughlin says rising costs and missed targets make the plan untenable.
He blamed Network Rail, saying it should have foreseen that the improvements would cost more and take longer.
But the chief executive of Network Rail, Mark Carne, told the BBC that its five-year £38bn programme, was simply too ambitious.
Kamal Ahmed reports.