Speaking at the CBI annual conference he said: “In the 50s it took us eight years to design and build the first 50 miles of the M1.
“Today it can take that long just to widen one section of a motorway.
“So we are speeding things up.
“Since we came to office we haven’t just announced a load of road and railways schemes, yes – we have actually got diggers on the ground on the A23, the M62, the M4, M5 and M6.
“What’s more it’s our ambition to cut the time it takes to upgrade our roads in half.
“So we are determined to dismantle some of the procedures that have been slowing us down and slowing you down.”
Cameron acknowledged that previous promises had been kicked into the long grass by Whitehall.
He said: “None of this will mean much unless we have a change of culture in Whitehall too.
“Whitehall has become too risk-averse, too willing to say ‘no’ instead of ‘yes’.
“But for the sake of our country’s progress we have got to cut through this.
“I want every Department in Whitehall to be a growth department.
“I’ve insisted that every Permanent Secretary has growth as a key objective.
“And I want every Minister and every official to understand that the dangers are not just in what you do but what you don’t do that the costs of delay are felt in businesses going bust, jobs being lost, livelihoods being destroyed.”