Drivers are bracing themselves for two years of slow going on the A34 as work begins to replace the Wolvercote Viaduct north of Oxford.

The bridge, which carries the A34 over the A40, the Oxford Canal and the railway line to Banbury, is being replaced at a cost of £44.4m.

The Highways Agency says it is no longer cost-effective to repair salt and water damage to the structure of the original bridge, which opened in 1961.

The project will take two years to complete.

The first phase will see lanes on the A34 narrowed and a 40mph speed limit in force while a temporary bridge is built to the east of the viaduct.

Speed limits will be enforced by cameras and the A34 will have just one lane open overnight at times.

Once the temporary bridge is completed, southbound traffic will be diverted on to it and the original northbound viaduct will be demolished, so its replacement can be built on the existing alignment.

Northbound traffic will use the existing southbound side for this phase.

When the new northbound bridge is complete, traffic will switch to that while the old southbound structure is demolished and replaced.

Highways Agency spokesman Roger Jones said: "It needs replacing. We could have shut the whole thing and diverted people around other parts of the county, but we are keeping two lanes open in each direction throughout, other than some odd nights.

"It will slow people down and they will need to spend more time getting through there, but it is only 500 metres of slightly narrower lanes."

Up to 3,400 vehicles an hour and 40,000 vehicles a day pass over the viaduct in each direction, according to the agency.

Cormac O'Hara, the manager of the Barcelo Oxford Hotel, at Wolvercote roundabout, said: "The construction of the temporary bridge could cause huge problems on the A34.

"I imagine, to begin with, there will be an awful lot of chaos on the A34 and tailbacks. I think the local community will avoid it like the plague, which could affect businesses which thrive on local trade."

But Mr O'Hara, who also sits on the Oxford Marketing Group and Destination Oxford committees, accepted that the existing viaduct needed replacing.

He said: "I think in the mind of the traveller it's just going to be something they have to put up with.

"There are no diversions and it's such an important route that people will just have to go through it."

Terry Field, of haulage firm Oxford Logistics, which has its depot in Didcot, said: "Even if it's closed at night, it will cause problems for lorries coming up from the south.

"We work in the evening and early hours but we don't know at this stage what will happen."

  • A Highways Agency exhibition about the project will be held at Wolvercote Young People's Club, in St Peter's Road, on Friday, May 30, from 3pm to 9pm and the following day from 10am to 4pm.