Walnut Creek drivers traveling to San Francisco this weekend should plan for delays and detours as Caltrans closes westbound Interstate 80 beyond the Bay Bridge.

All westbound lanes between Fifth and 15th streets are scheduled to close from 11 p.m. Friday, Oct. 23, until 6 a.m. Monday, Oct. 26, according to Caltrans’ latest notice.

The Bay Bridge will remain open. Eastbound I-80 lanes toward the bridge and East Bay will also remain open, although congestion could affect traffic in both directions.

Caltrans spokesperson Pedro Quintana told KQED that drivers should prepare for delays of at least 20 to 30 minutes. Actual backups will depend on traffic volumes, trip timing and drivers’ routes.

Detours and alternatives

Caltrans’ project page identifies Fremont Street and Fifth Street as exits for diverted traffic. Fifth Street will be the last exit before the closure.

The Harrison Street on-ramps to westbound I-80 at Fourth and Seventh streets will also close. Drivers should follow posted detours to reach southbound U.S. 101, I-280 and other destinations.

Caltrans recommends public transportation or alternate crossings, including the Richmond-San Rafael, San Mateo and Dumbarton bridges.

AC Transit spokesperson Robert Lyles told KQED that weekend transbay buses are expected to operate on regular schedules. Riders should still check for service updates because roadway congestion could affect travel.

Why the freeway is closing

Crews will place polyester concrete on the freeway deck as part of Caltrans’ Fab-4 rehabilitation projects.

The Central and Bayshore viaducts are about 71 years old, according to Caltrans. The work is funded by Senate Bill 1, the Road Repair and Accountability Act of 2017.

Events and travel updates

The Warriors’ home opener against Memphis begins at 7 p.m. Friday, before the closure starts. Doja Cat’s Sunday, Oct. 25, concert at Chase Center takes place during the shutdown.

KQED reported that San Francisco parking control officers will help manage traffic on city streets.

The construction schedule is weather dependent. Drivers should check Caltrans QuickMap before leaving or call 1-800-427-7623 for highway conditions.

A separate southbound U.S. 101 Bayshore Freeway closure is scheduled for Nov. 6-9.