VITAL repair work to a busy flyover will cause delays to thousands of commuters and traders for up to three weeks.

Transport for London (TfL) will carry out what it describes as essential repair work to the A406 Redbridge flyover in South Woodford from April 30 bringing potential gridlock for residents and businesses using the route in morning and evening rush hour.

Traffic will be forced through a contraflow system for the duration of the works, which will produce a bottleneck effect by halving the number of lanes available.

Heavy vehicles will be redirected to the A113 roundabout while bus routes will be redirected.

Cllr Richard Hoskins, of Church End ward, predicted that the surrounding roads would be “gridlocked” and that traffic jams could affect areas as far away as Barking and Dagenham due to the arterial nature of the route.

“There’s so much traffic on the road that one blockage will affect all other routes dreadfully,” said Cllr Hoskins.

“It’s a key junction but we’re stuck because the repair works need to happen.”

TfL say that four expansion joints within the flyover need replacing to enable the junction to continue to support heavy loads.

The joints allow the section of road to expand and contract when the bridge moves as heavier vehicles use it, and will replace temporary repairs made in late 2010.

Essex Federation of Small Businesses development manager, Keith Brown, said: “The work is going to cause major disruption for businesses which rely on the North Circular Road.

“We would encourage businesses to record any downturn in their trade and to approach the relevant authorities to see if they are able to claim any relief on business rates or other assistance if trade is adversely affected.”

TfL say the roadworks will take place from Mondays to Fridays between 8am and 6pm - affecting both rush hours - and on Saturdays between 8am and 2pm.

Dana Skelley, director of roads for TfL, said: “This essential work is vital to ensure that the structure can remain open to traffic.

“During this work we will ensure that disruption for road users and local residents is kept to a minimum.”