DRIVERS will be faced with six weeks of diversions during overnight closures at Southwick Tunnel on the A27.
The Highways Agency said the tunnel cross passage doors needed to be replaced, along with resurfacing, maintenance and other associated work.
The A27 will be closed from Holmbush to Hangleton during the works at Southwick Tunnel, starting in February.
During the closures, traffic affected will be diverted via Old Shoreham Road and the A293 in Portslade.
Donna Walker, network delivery and development, said: “It is expected that the work would take place for approximately six weeks, starting on or after Monday, February 2, between 8pm and 6am (maximum period).”
The required Temporary Traffic Restrictions order would come into force on January 31 and have a maximum duration of 18 months.