SAN FRANCISCO -- Caltrans has plans for roadwork on several major highways and interstates.

Highway 101 from Whipple Avenue in Redwood City already has some lanes closed in both directions this weekend through Monday at 5 a.m.

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Starting on Monday, two eastbound and two westbound lanes of Interstate Highway 80 in San Francisco will be closed nightly for repairs, Caltrans announced.

The work will replace concrete barriers and tubular railing damaged by vehicle collisions, the transportation agency said Friday.

The lanes will be closed from 10 p.m. to 6 a.m., with crews focusing on one direction at a time, Caltrans said. One lane will be open where work is under way.

Motorists may experience significant traffic delays, Caltrans said.

Other barrier repairs will require the full closure of U.S. Highway 101 (also known as the Central Freeway) for 55 hours beginning Oct. 4, Caltrans said.