Residents fear traffic bottlenecks and gridlocks
People living near the A338 Bournemouth Spur Road fear their roads will become a rat-run for motorists when a £26m refurbishment begins in autumn.
Reconstruction of 6.5 miles (10.5 km) of the main route and its drainage systems will take six-months.
Only one lane will be open in each direction during the programme.
Residents say they are worried about drivers trying to avoid the delays. The council said it has "full traffic management in place".
A single-lane restriction put in place at the Ashley Heath interchange in February, to clear-up drainage ditches in the verges adjacent to the A338 to solve problems of carriageway flooding, caused major delays.
Resident Mike Dyer told BBC Radio Solent: "One lane in each direction led to gridlock on our local roads while they carried out preparatory work [for reconstructing the A338].
"[But] I think local people recognise the work is essential."
Rob Turner, from Dorset County Council's highways department, said: "Access is being maintained for residents and there will be people at the top and bottom of the element of the road that is being closed.
"These works are inevitable and disruption is part of that."