TRAFFIC jams are now so bad in Oxford concrete is setting in the back of delivery lorries.

The firm supplying builders at the £440m Westgate Shopping Centre said yesterday roadworks “chaos” on the A40 was costing it thousands of pounds in “spoilt” mixture.

Hanson said concrete mixed at its Stanton Court plant has to be laid within two hours – or sent back for disposal at a cost of up to £800 per load.

But because of the works at the Wolvercote and Cutteslowe roundabouts journeys are often taking 90 minutes or more.

Now the company has called on highways authority Oxfordshire County Council to ease route restrictions so it can avoid North Oxford.

Head of communications David Weeks said: “Concrete has a shelf life. If it was an extension in someone’s garden where we were offloading material into a nicely-positioned slot we could be in and out in 20 minutes.

“But this is a busy site with high standards and we are arriving with only half an hour or less to get it in place.

“We are losing thousands of pounds because we have to bring back trucks to dispose of the concrete because it has spoiled.”

The news came as business leaders warned that traffic in the city remained a “big issue” that was hurting trade.

Graham Jones, of business group ROX, said: “The A40 can be pretty bad even without roadworks due to the volume of traffic.

“The county council has to think about the long-term with these schemes, but for businesses in the short term the impact of these works on trade is a big issue.”

Hanson’s mixing trucks currently travel from its site near Dix’s gravel pit via the A415 and then the A40 due to county council restrictions.

But Mr Weeks said the firm wanted these lifted so it can divert 21 trucks via Sutton and the Swinford Toll Bridge into West Oxford. He added: “We will make it clear to drivers that we do not want any complaints and would only be talking about one truck every half an hour, so you would not see a flotilla of lorries charging down country roads.”

According to Hanson, it cannot use additives to make the concrete last longer as the firms behind the redevelopment of the Westgate have said they will not accept it.

On Monday a panel of councillors will be asked to approve the route change.

But the proposal has been described as “absolutely unsatisfactory” by county councillor Charles Mathew, who said it would disrupt the lives of people in Sutton and set a precedent for other companies to follow suit.

He said 40 residents had complained and that the use of the toll bridge by lorries could cause delays and potentially be dangerous.

County council leader Ian Hudspeth said: “We understand the concerns the businesses have about the roadworks. However, even though they cause disruption it is about the final result.

“But Hanson were aware there would be roadworks when they opened this plant and it is surprising that they didn’t take this into account.

“I would not like to prejudge what the planning committee will do on Monday but clearly commercial decisions have already been taken.”

The new Westgate centre with more than 100 new stores, 25 restaurants and cafés, a cinema, roof terrace and public spaces will open in 2017.