Northbound Highway 101 Fully Closes Through the Hospital Curve Over Labor Day Weekend

Caltrans will fully close northbound U.S. 101 through the Hospital Curve in San Francisco over Labor Day weekend, from Friday, September 4 to Monday, September 7, and again from Friday, September 18 to Monday, September 21. Two southbound weekend closures follow in October. The work is part of the Fab 4 Hospital Curve Rehabilitation project, which started in fall 2025.

The September Closures

Caltrans announced the September dates on August 10, describing both as full closures of northbound 101 between Cesar Chavez Street and 17th Street. SFMTA’s August 20 traffic advisory describes the same Labor Day closure as running from Cesar Chavez Street to the 7th Street exit. The two agencies give different northern endpoints, so check Caltrans QuickMap before you drive it. Either way, the closed stretch is the Hospital Curve, the bend of 101 that passes Zuckerberg San Francisco General.

Where to Go Instead

Caltrans lists northbound I-280 and northbound Potrero Avenue as the alternates. Its published detour map sends traffic coming from SFO onto I-380, then I-280, rejoining northbound 101 near Bernal Heights. Traffic heading the other way, from downtown toward the airport and the Peninsula, takes I-280 through I-380 and back onto southbound 101.

If you are catching a flight that weekend, BART runs to the SFO station from downtown San Francisco, and Caltrain runs from 4th and King to Millbrae, where BART connects to the airport. Neither uses 101.

This Weekend Comes First

Before the full closures, lane reductions on the same stretch start at 11pm on Friday, August 21 and last until 6am Monday, August 24. Two northbound lanes and two southbound lanes between Cesar Chavez and 17th are closed for median work, with two lanes staying open in each direction. Caltrans is pointing drivers to I-280 in both directions that weekend.

Southbound Closures in October

SFMTA’s advisory adds two southbound weekends: October 2 to 5 and October 16 to 19, with southbound 101 fully closed between the 9th Street and Civic Center exit and the Cesar Chavez exit for concrete pavement replacement. Southbound I-280 via 6th Street and southbound Potrero are the listed alternates. Caltrans says more details will follow.

Other Roadwork the Same Weeks

Caltrans is also running overnight lane closures on eastbound I-80 on the Bay Bridge lower deck most nights through October 2026, from 10pm to 7am Sunday through Thursday, to install a temporary work platform. All lanes reopen each morning. In Chinatown, the Broadway Tunnel is down to one lane in each direction, which SFMTA now says will hold for about 14 months.

For updates as schedules are confirmed, Caltrans points drivers to sfhighwayprojects.com and to QuickMap for real-time conditions. Our August guide covers the rest of what is changing around the city this month.

Photo: Famartin, CC BY-SA 4.0, via Wikimedia Commons.