Drivers will be able to use part of the Norwich Northern Distributor Road for the first time - with a section of almost four miles having been officially opened.
By 6am on Saturday, almost four miles of the 12.5 mile dual NDR carriageway - between the A1067 Fakenham Road and A140 Cromer Road - will be open to the public.
The rest of the road, which will eventually stretch from the A1067 to the A47 at Postwick and has been given the number A1270, is due to open in sections.
The part between the A140 Cromer Road and the A1151 Wroxham Road could yet open by the end of the year, while the section between Wroxham Road and Postwick is earmarked for a mid March opening.
On Friday, Norfolk county councillors, Broadland district councillors, council officers and contractors took part in a ceremonial ribbon-cutting on the western part of the road to celebrate that section's completion and tomorrow's opening.
A Konectbus, carrying the guests, followed two Bentleys and a Jaguar up and down the length of the road which has been completed.
Martin Wilby, chairman of Norfolk County Council's environment, development and transport committee, said he was delighted that the first section of the road would be in use from tomorrow.
He said: 'It's a good road and it will make a difference to our city and county. It will now start to make a difference for thousands of people and will continue to do so for years to come.
'Local residents will benefit as traffic switches to this dual carriageway from unsuitable rat runs.'
He said, as well as the economic benefits, the road had also allowed changes to be made in Norwich city centre, such as the pedestrianisation of Westlegate.
But controversy still surrounds the final bill for the road, with the £179.5m budget having risen by around £25m and the council locked in talks with contractor Balfour Beatty over the final figure.
Steve Morphew, leader of the opposition Labour group at Norfolk County Council, said: 'The NDR is a good thing for the development of Norwich. It should be celebrated as that, not as a road scheme.
'Although I was instrumental in making it happen I won't join the flag waving until we have an explanation of the political mismanagement that led to the projected £25m overspend - more than £60 for every single household in Norfolk.
'The county council is accountable for that money, the overspend has to be funded by tax payers and somebody has to take responsibility.
'I hope those seeking to take credit for the new road today will be as keen to take responsibility for the huge overspend.'
While the road has been hailed by supporters, including the New Anglia Local Enterprise Partnership, as providing an economic boost, critics say the money would have been better spent on sustainable transport.
Mr Wilby said a report on the overspend - and how it would be funded - would come before the county council in the new year.
When the road opens tomorrow, which council officers say will happen no later than 6am, the road will operate as part of the county highway network.
Most of the route will be subject to the national 70mph speed limit for dual carriageways. The exception will be the eastbound carriageway from the Drayton Lane roundabout to the A140 Cromer Road junction, where a 40mph speed limit will be in force and traffic will be filtered into a single lane before the slip road off the new dual carriageway.
Motorists are asked to take particular care on the new road, especially at roundabouts, where crossing traffic will not be used to traffic emerging from the NDR.
Officers at County Hall carried out traffic modelling of other roads before deciding to open the NDR in sections and are confident they will cope even though the entire NDR is not yet open.
Road closure
While one road opens, another closes. Council bosses said Green Lane West, Rackheath, will be closed from 6am tomorrow for one day.
There will be no access to Rackheath Industrial Estate or most of Green Lane West from the A1151 Wroxham Road.
The diversion will be via Norwich Ring Road and Salhouse Road, joining Green Lane West at the Sole & Heel roundabout in Rackheath.
The weight restriction on Green Lane West will not apply to vehicles needing access to the industrial estate.
The small number of Green Lane West properties between the point of closure and Wroxham Road will be accessed from existing junction with Wroxham Road. Other vehicles attempting this route will not be able to get through.
When the road reopens late on Saturday, traffic will use the new link road and new junction with the A1151 Wroxham Road.
Two-way traffic lights will be needed, and vehicles will be running on a temporary surface until the final surfacing is carried out next Saturday (18) under another one-day closure of Green Lane West.
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