Motorway drivers face long delays while maintenance work is carried out on the M23.
Engineers will be working alongside the motorway at its Pease Pottage junction near Crawley from Monday.
Existing crash barriers will be removed and replaced to meet latest safety standards.
A temporary safety barrier and 50mph speed limit will be put in place at all times during the works.
The slip roads approaching the interchange and the roundabout will be reduced to a single lane.
Ing Fischer, Highways Agency route manager, said: "The works are part of a nationwide programme to upgrade existing crash barriers to new safety standards.
"Drivers are advised to allow extra time for their journeys while the works are underway."
The works will last four weeks and will take place between 10am and 4pm.
The news is a double blow for drivers who are already experiencing problems caused by major roadworks on the M25.
For more information, call 08457 504030.
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