Nighttime closures start Monday night on the Yauhannah Bridge on Highway 701 at the Horry-Georgetown line.
The bridge will close nightly at 8 p.m. and open at 6 a.m. Monday through Saturday.
Traffic will be detoured from Browns Ferry Road in Georgetown County to Lucas Bay Road in Horry County.
The work is required to stop the foundation from settling on the nearly 60-year-old bridge.
Repairs are expected to continue through the end of the year.