Work to tie new roundabouts on the route of the Norwich Northern Distributor Road in with existing roads could be carried out overnight.

Bosses behind the £178.5m project say that working overnight, in areas such as Fakenham Road, for a handful of nights, would speed up the project, cut overall traffic disruption and help ensure a better finish.

The council and its contractors currently have permission for work between 7am and 7pm, but are seeking the go-ahead to vary those hours.

Signs have already appeared on the A1067 Fakenham Road, where motorists have been warned there could be four overnight closures – from 8pm to 6am – from Monday, September 12.

John Birchall, Norfolk County Council's community liaison officer for the NDR project, said: 'Although signs have gone up alerting motorists of planned overnight closures, these will only go ahead if consent is granted.

'Putting up the signs may seem like jumping the gun, but we've got to give notice on site or we can't do the work, even if consent is given.

'A key consideration will be the potential for disturbance of people living nearby.

'The advantages of working under a full road closure would be faster working, reduced overall traffic disruption, and a better finish, with fewer surface joints.'

Meanwhile, progress is being made on a number of bridges along the route, including Marriotts Way – the 'green bridge' that will carry the hedgerow over the NDR to maintain it as an important foraging route for bats, Middle Road in Great Plumstead and Buxton Road, near Spixworth.

Mr Birchall said: 'A key structure is the double bridge that will carry the NDR over Plumstead Road and the Norwich to Sheringham Railway. The bases are now in on the road bridge, and piling for the railway bridge has started.'

Contractors are hoping the 12.5-mile road, which will stretch from the A47 at Postwick to the A1067 Fakenham Road, will be completed by Christmas next year.