Work will begin to improve Loddon Viaduct on Wednesday, with the A329M reduced to one lane in each direction, instead of two, with a contraflow system in place.
The eastbound (Bracknell-bound) Winnersh Triangle exit will also be shut for the duration of the work, which will last until early morning on September 2.
There will also be lower speed limits on the affected section around the viaduct. Wokingham Borough Council had originally planned to do the work in January but postponed it after preparatory work in October caused massive disruption on local roads, with delays of up to two hours for motorists.
Work is now taking place during the school summer holidays and council leader Keith Baker is urging commuters not to panic.
He said: “Obviously we don’t want a repeat of what happened last October and have looked long and hard at how we are going to manage this maintenance work.
“Yes of course there will be some disruption but we want to make sure we minimise it as much as possible.
“We ask that if motorists can possibly avoid it while the works are happening, then please do.
“By investing in this important piece of the road network, it both ensures the future of the viaduct and improves the experience and safety of people using the road. It is also key to building sustainable communities, which depend on the right infrastructures being in a fit state to serve them.”
Work being carried out includes replacing the bridge’s noisy joints, installing new permanent concrete safety barriers, improving drainage and signs, and giving the dual carriageway a low-noise road surface.
The council has sent 25,000 letters to residents and businesses in Winnersh, Lower Earley, Shinfield, Woodley, Earley and Emmbrook, warning them about the work and the second phase is planned for next summer, which will concentrate on the westbound road towards Reading.