Getting diggers in the ground on the A47 could take more than five years, the Department for Transport has said.

The Highways Agency will have to secure planning permission and land to upgrade the trunk road.

It will also emerge – in a study which will be published over the coming weeks – that there were not enough 'end-to-end' journeys along the A47 at present to 'justify' full dualling.

While transport officials said that they will not do the whole of the road for now, a spokesman said: 'We will have to keep the position under review, and if the situation improves, we can revisit doing further schemes.'

A Department for Transport spokesman said: 'The publication of this document is the green light to the Highways Agency to gear up to deliver these schemes. They will start committing resources to developing the schemes, designing them and the procurement.'

He said that the A47 would be a 'little bit more developed' than some other road projects because it had been a feasibility study.

He said work would continue on the Acle Straight.

'It might not be dualling the Acle Straight. The key priority for the Acle Straight is we need to strike a balance between the environment and the economy and social needs. The key issue on the Acle Straight is the safety record. The will be our priority. We will see what might be possible at that point.'

He said the safety work could include barriers and widening the embankment, as there is currently little resilience to stop a car going into a ditch.