Resurfacing work will begin on the A26 between Beddingham and Newhaven on Monday (September 23).
Sections of the A26 will be resurfaced and ten dead elm trees next to the carriageway will be removed.
The work will involve overnight carriageway closures and is due to be completed on Friday October 11, weather permitting.
Highways Agency project sponsor Anita Waterton, said: “The diversion route is a longer route, and I advise anyone wishing to use the A26 overnight to plan their journeys in advance and allow extra time for their journeys.”
The work will be carried out overnight, between 8pm and 6am, Monday to Fridays, when traffic is lightest, to minimise disruption.
The A26 will be closed, in both directions, between the Beddingham roundabout (A27) and Newhaven (B2109). A fully signed diversion will be in place via the A259 and either the A23 or A270.
Access for residents and businesses within the closure will be maintained locally.