Despite the complexities, which include a damaged carriageway with culverts spanning beneath it, highways officers and contractors continue to make good progress.
Work has included gabion baskets being positioned at the foot of the bank to strengthen the overall integrity of the structure.
The section of road, just south of the Seaford College entrance, has been closed for safety reasons following a slippage of earth over a culvert that spans beneath the carriageway.
Subject to unforeseen factors that can delay any construction project, such as severe weather, the ambition is for the road to be reopened before Christmas.
Businesses in Duncton, Petworth and the surrounding areas have been able to open as usual throughout and will continue to do so.
Signed diversions are in place. Please keep up to date online via: https://one.network and on Twitter @WSHighways
More information is available at www.westsussex.gov.uk/duncton