Motorists will face six weeks of disruption on the A23 as new lighting is installed.
The work, which will be carried out overnight, will see carriageway and lane closures.
Workers will start today and hope to finish by April 17.
More than 50 lighting posts will be moved and replaced with new columns which feature a safer design.
Maintenance work will also be carried out on 120 lights in the area.
The lights were installed more than 20 years ago and need to be moved to be in line with current safety standards.
Peter Phillips, from the Highways Agency, said: “Safety is a top priority for the Highways Agency.
“The lighting along this section of the A23 needs to be maintained and we are taking this opportunity to relocate 56 columns further away from the carriageway to reduce the likelihood of them being hit by vehicles.“The work has been planned to take place overnight, when we know that traffic flows are at their lowest, to minimise disruption.
“We would advise anyone wishing to use the A23 to plan their journeys and allow extra time.”
Work will be carried out each day between 8pm and 6am.There will be overnight carriageway closures will be required – with one lane on the opposite carriageway also closed – between Pease Pottage and Bolney.
From today until March 18 the southbound carriageway will be closed followed by the northbound between March 19 and 25.
The road northbound will be closed again between April 1 and 4.
A signed diversion will be in place along the A264, A24 and A272.
One southbound lane will also be closed overnight from March 23 to April 17 between Bolney and Hickstead to move lamps.
Some slip roads may also be closed and diversions will be put in place directing drivers to the next turn off.
For more details visit www.highways.gov.uk.