Caltrans is closing the southbound on-ramp of Highway 101 between Fairview Avenue and Patterson Avenue Thursday from 8 p.m. to 6 a.m.
Officials say the emergency ramp closure is necessary for crews to add two drainage inlets on the southbound shoulder of the highway.
Crews will also be grinding and paving the road.
Drivers heading southbound can use the exit at South Patterson Avenue. Caltrans officials say delays shouldn't be longer than 15 minutes.
Lane and ramp closures will continue next week Monday through Thursday from 9 a.m. to 4 p.m. and Friday from 9 a.m. to 2 p.m.
This project should be complete in mid-February, weather permitting.
Caltrans wants to remind drivers to move over and slow down with driving through highway construction zones.