THE biggest weekend in Swindon’s social calendar could turn into the biggest traffic nightmare the town has ever seen.

The Adver has learnt that major roadworks on the M4 motorway are scheduled to close junction 16, the West Swindon exit, at exactly the same time as the BBC Radio One’s Big Weekend comes to town.

The junction would be closed from mid-evening on Saturday, May 9, to 10am on Sunday, May 10, to allow the new bridge at South Leaze to be lifted into place.

The scenario could lead to horrendous tail-backs as 20,000 concert goers struggle to exit Lydiard Park.

The Highways Agency and Swindon Council are working to find a solution to the problem, but with only five weeks left until the flagship music event, time is running out fast.

It could lead to Wootton Bassett becoming the main route into Swindon for hordes of music fans, particularly if traffic is diverted off the M4 at junction 17.

The town’s mayor, Mike Leighfield, said it was the first he had heard of the plans, but that he would be seeking to ensure that Wootton Bassett did not become a rat run.

He said: “This would be a catastrophe for the town. It would leave us completely gridlocked.

“Our ordinary shoppers would not be able to get to the car parks. And what would happen if there was a repatriation that day?

“People coming from outside the town wouldn’t know where they were going and we would see the High Street absolutely jammed. It would be an absolute fiasco.”

It is now a race against time for Swindon Council and the Highways Agency to switch the work to another weekend or face a spanner in the works of the much trumpeted event.

Robin Miller, from the Highways Agency, said: “The junction is scheduled to close on May 9 and 10 to lift the new bridge into place at South Leaze. We are in negotiations with Swindon Council at the moment to look at alternative weekends.”

Gavin Calthrop, Swindon Council’s head of communications, said: “We are in discussions with the Highways Agency about that weekend and are actively looking for a solution.”

The BBC Radio One’s Big Weekend has been a major success story for Swindon, with claims that it could bring up to £1.5m into the local economy.

The Adver broke the story exclusively back in November, when we announced that one of the BBC’s biggest annual music event could be coming to Lydiard Park.

The official confirmation came two weeks ago when Radio One star, Chris Moyles broadcast live from Swindon, announcing that Snow Patrol and N-Dubz would be among the stars.

More big names and details of the event are set to be announced in the next week.