Dual carriageway to close over weekend
About 50 minutes will be added to car journeys because of resurfacing works on the A34.
National Highways carried out work between East IIsley and Chieveley last month but set aside a further weekend as a contingency.
That work is now set to go ahead later from 21:00 BST, through the weekend until 06:00 on Monday.
The agency will also be carrying out safety barrier renewals, repainting white lines, and litter picking.
It said the closure was required to enable it to complete the works safely.
A signed diversion will be in place via the A34, A40, M40, and A404/A404M, to rejoin the southbound A34. It is expected to add an additional 50 minutes to journeys.
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