Roadworks look set to cause a year of traffic chaos for motorists on one of the county's busiest routes.

Drivers are preparing for 13 months of misery on the A27 as work begins to rebuild two roundabouts.

Queues up to three miles long are already common outside Lewes as engineers construct a flyover between Southerham and Beddingham.

Now their two roundabouts are to be rebuilt, with traffic cut back to one lane and a 40mph speed limit extended.

The AA believes queues could stretch as far back as Falmer at peak times and advised employers to allow staff to take on flexible hours to avoid the huge tailbacks.

Motorists already struggling to find alternative routes say the road used by 30,000 vehicles a day would become a "nightmare".

Rebuilding the roundabouts is part of the £32 million scheme to improve the A27 troublespot and is not scheduled to finish until July next year.

Highways Agency project leader Chris Bacon said: "We're reaching a situation now where we are rebuilding the roundabout and we do anticipate delays.

"We think it's best to be up front, warning drivers and thanking them for their patience.

"We feel the roundabout situation will add to journey times. It's hard to put a precise time on it but it could be much worse than it is now in the peak hours."

Motorists said they are already suffering agonising queues on either side of the roadworks.

Lyle Acott, of Glenthorn Road, Bexhill, has been using the stretch of road twice a day for five years as she travels to work in Hollingbury.

She said: "At peak times we've had tailbacks as far as Kingston and I've already had to add 20 minutes to my journey.

"When I saw the signs saying it was going down to one lane I just thought, 'What a nightmare.' I don't know what I'll do now. It might mean I don't get home until 8pm.

"I understand the work's got to be done but I'm not looking forward to the next year because I know its going to cause chaos."

Mike Legg, of Bolebrook Road, Bexhill, does a similar journey.

He said: "We've had tailbacks as far as Middle Farm to the east and Kingston to the west. This is just going to make it worse.

"The portion of the road near Southerham is the only place where it speeds up at the moment. It's the only release to the bottleneck being created."

Restrictions will take effect from Monday at the Southerham roundabout, where work is due to take six months.

However, life will become even more difficult for commuters in August when work also begins on the Beddingham roundabout - due to last until July 2008.

Paul Watters, the AA's head of roads policy, said: "It's a bad time of the year for a road along the south coast for this kind of work - when it is at its busiest.

"It's been a blight for a long time so this is short-term pain for long-term gain.

"What tends to happen is that regular users will adjust their times and if it gets really painful employers will need to get flexible, allowing their staff to stagger their hours to avoid peak times.

"If you take a lane out of the roundabout it will halve its capacity so you could end up with traffic backed up as far as Falmer."

The Highways Agency said traffic will be reduced to a single lane in both directions west of Southerham.

It will also be reduced from one to two lanes around both roundabouts, slowing traffic but allowing crews to work safely.

A 40mph speed restriction will be extended for a mile towards Brighton and remain in place with narrow lanes between the roundabouts.

Mr Bacon added: "The existing works are on programme. We've been able to make good progress and the railway bridge is well on its way.

"The aim is to have it open by the end of the year so it's all on schedule. The traffic management we've had running since January has been working well. There's obviously some queueing but there was queuing before we started.

"Peak hours could be a little worse than you might expect."