TODAY is D-Day for thousands of motorists who could face lengthy delays as work on the £5.7m Canford Bottom roundabout project starts in earnest.

The first 30mph speed limit was in place on the A31 last night and lanes have been narrowed so engineers can start on the busy junction, between Wimborne and Ferndown.

Many locals believe the project will spell daily gridlock until next spring, when it is scheduled to be completed ahead of the 2012 Olympic sailing events in Portland and Weymouth.

Colehill Parish Council chairman David Mitchell has warned this expected gridlock will “make it virtually impossible for local people to enjoy any form of normal life”.

The project will see the Canford Bottom roundabout bisected by a dual carriageway.

Parish council highways committee member, Susan Cowsill, told the Daily Echo: “We are seriously concerned about the impact this is going to have on local residents and local businesses. We think it is going to cause a lot of congestion.

“There are a lot of local people who feel it is going to cause problems. It may be that at the end of all this disruption we get a better junction, but it is a long time to wait.”

Around 4,000 vehicles use the roundabout during the morning rush-hour alone.

A number of A31 overnight closures and local road closures will also disrupt traffic throughout the remainder of 2011 as the works, which form part of the Olympic Route Network, continue.

Workers will be on site 24 hours a day, Monday to Friday. In November and December the new dual carriageway will be built.

Some angry residents have already called for traffic protests on the finished junction.

However, Neil Andrew, Highways Agency asset manager, said work had been specifically planned to minimise disruption. He has also urged drivers to adhere to speed limits and plan their journeys before setting off.

A Highways Agency spokesman said: “During the first few weeks, work will include the removal of existing road markings, road studs, signage, safety barriers and lighting.

“Work will then start on building the new dual carriageway through the centre of the roundabout during November and December.

“Details of road closures will be publicised in advance and each closure will have clearly-signed diversion routes in place.”

The improvements will finish ahead of the London 2012 games.

Mr Andrew said: “Some of the work will be noisy but we wish to reassure local people that we will constantly monitor noise levels and take every measure possible to mitigate the effects.”