Hurn Road is likely to see an increase in traffic when the project to rebuild the Spur Road gets underway from September 6.
To ensure it can cope with extra vehicles, work is needed to widen a “pinch point” between the junction with Hillside Drive and the southbound Blackwater junction.
By widening the carriageway 1.4m, drivers heading north along Hurn Road toward the airport or wanting to take the A338 northbound, will be able to pass drivers waiting to turn right onto the southbound A338.
Cllr Margaret Phipps, county councillor for the area, said: “This small section of widening will make a big difference to drivers using this junction.
“There is never an ideal time to carry out this type of work but it’s essential that it is finished before the A338 major scheme starts in September, when this route will no doubt become busier.”
There will be “some carriageway incursion” as the works are carried out, DCC says. There are already delays due to Stop/Go boards near the roundabout on Hurn Road.
The £22m scheme, funded by the Dorset Local Enterprise Partnership, will see the A338 Spur Road completely rebuilt between Ashley Heath roundabout and Blackwater Junction.The work will be carried out in phases between September 6 and May 31, 2016. The Spur Road will remain open but work will be carried out on one side of the carriageway at a time, with 40mph contraflows in place on the other side.