More than 120 signs and posts will be repaired or replaced along the A2 between Brenley Corner and Dover in Kent.
The work will start next week and will take seven weeks. It will involve lane closures, temporary traffic lights and temporary speed limits.
Kevin Bown, Highways Agency Asset Manager, said: “We will be repairing or replacing a total of 121 signs and posts over a distance of almost 25 miles along the A2.
“Some of the signs are coming to the end of their life and we will upgrade them to the required standards to help road users with their journeys.
“The work will be carried out overnight between 7pm and 6am, when traffic flows are lowest, to minimise disruption to road users.”