The work will improve safety by the introduction and installation of more than 70 new, enhanced and clearer signs for drivers.
Philip Sheppard, Highways Agency Asset Manager said:
Safety is a top priority for the Highways Agency and the installation of these signs will help drivers on their journeys along the A31, helping them pick the right lanes for their trip and avoid last minute lane changes.
Installing these signs will require overnight closures of the A31 but as well as installing these signs we will use this opportunity to carry out road surface repairs and maintenance work on roadside drainage.
The work on the westbound carriageway will be carried out with full overnight closures between the M27 and the A338 Ringwood roundabout, between 10pm and 6am, on:
Monday 18 August, Tuesday 19 August, Tuesday 26 August, Wednesday 27 August, Monday 1 September and Tuesday 2 September.
Further overnight closures on the westbound carriageway between Poulner Hill and the Verwood Interchange are scheduled for Thursday 28 August, Wednesday 3 September, Thursday 4 September and Monday 8 September.
Clearly signed diversions will be in place during the closures. Drivers travelling westbound will be diverted via the A326, A35, A3060 and A338.
The work on the eastbound carriageway will be carried out with full overnight closures between the Ashley Heath roundabout and the M27, between 10pm and 6am, on Wednesday 20 August and Thursday 21 August.
Drivers travelling eastbound will be diverted via the A338, A3060, A35 and A326.
Members of the public should contact the Highways Agency Information Line on 0300 123 5000.
Journalists should contact the Highways Agency press office on 0844 693 1448 and use the menu to speak to the most appropriate press officer.