Rocks Road, which links Uckfield with Isfield and Piltdown, is to be closed to through traffic for six weeks from July 30 for roadworks.
During the same period, there will also at times be temporary traffic lights on the A22 for safety barrier upgrades.
The restrictions will be in place for bridge repairs on Rocks Road.
Works will include waterproofing, surfacing and safety barrier repairs.
The diversion for traffic which would normally use Rocks Road will be via Church Street, Uckfield High Street, London Road, A26, A22, A272, Shortbirdge Road, and vice-versa.
Some of the works will take place at night and maybe noisy.
The two-way traffic lights on the A22 will be to facilitate the safety barrier upgrade.
The lights will not be in operation during peak hours and will be removed outside of working hours.