Defensibility check: I’m reporting Caltrans’ own published closure schedule and detour guidance as-is; ride/drive-time impact will vary by exact route and time of night, so treat the specific detour recommendations as Caltrans’ guidance, not a personally tested route.
If you ride or drive through San Francisco’s Hospital Curve on US-101, mark your calendar: Caltrans is fully closing the northbound lanes between Cesar Chavez Street and 17th Street for an entire weekend, from Friday, September 18 at 11 p.m. through Monday, September 21 at 6 a.m. Southbound lanes stay open the whole time.
This is one closure in a multi-weekend series tied to the Hospital Curve pavement rehabilitation project, which started in fall 2025. If you’re planning a weekend ride or commute through the city, here’s what you actually need to know.
The closure, in plain terms
- What’s closed: All northbound US-101 (Bayshore Freeway) lanes between Cesar Chavez St. and 17th St., San Francisco.
- What’s open: All southbound US-101 lanes remain open the entire weekend.
- When: Friday, September 18, 11 p.m. through Monday, September 21, 6 a.m. — work crews run 24/7 during the closure.
- Why: Major pavement repair as part of the “Fab 4 Hospital Curve Rehabilitation Project,” part of ongoing long-term roadway rehab in that corridor.
This is the second of four planned weekend closures Caltrans has scheduled for this project. Two more follow: October 2–5 (southbound closed that time, between Cesar Chavez and 10th St.) and October 16–19 (also southbound). If you’re a regular through this corridor, it’s worth bookmarking Caltrans’ project page since the direction of closure flips between weekends.
Detour routes Caltrans recommends
For this specific weekend (northbound closed), Caltrans’ official guidance:
- Take northbound I-280 as your alternate route toward downtown San Francisco or the Bay Bridge.
- If you’re coming from the south and need surface streets: take southbound I-280 to the 19th Ave or Monterey Blvd exit, then to San Jose Ave to Guerrero St.
- Public transit is Caltrans’ explicit recommendation if you can use it — it’s the one option guaranteed not to hit the closure at all.
If you’re headed to or from SFO (airport or the rental car center) or coming from the Peninsula/South Bay toward the Bay Bridge or SF destinations, Caltrans has a dedicated detour map for that specific routing — worth checking before you leave if your trip touches the airport corridor this weekend.
What this means if you’re on two wheels
A few practical notes specific to riding this stretch, since Hospital Curve itself has a reputation among Bay Area riders for tight geometry even without construction:
- I-280 as a detour adds real distance and time, especially during a Friday-night or Sunday-evening rush — build in extra buffer if you’re timing a ride around dinner reservations or an event downtown.
- 24/7 work crews mean equipment and lane-shift signage will be active the whole weekend, not just during business hours — if you do end up near the closure zone (for example, checking whether southbound lanes are still moving normally), expect reduced visibility and tighter merges at night.
- This is a “check the night before” situation, not a “check last week” situation. Caltrans closures of this scale have shifted before due to weather; the agency explicitly notes “all work is weather dependent.”
Where to check for live updates
- 511.org or the 511 SF Bay X account for real-time regional traffic.
- Caltrans QuickMap (quickmap.dot.ca.gov) for live incident and closure mapping.
- sfhighwayprojects.com — Caltrans’ dedicated project page for ongoing schedule confirmations.
- Caltrans District 4 on X (@CaltransD4) or by phone at 1-800-427-ROAD for statewide conditions.
Bottom line
If your weekend plans route you through northbound 101 near Hospital Curve between September 18 and 21, plan on I-280 or transit instead — and if you’re a regular in this corridor, note that the next two closures (October 2–5 and October 16–19) flip to the southbound side, so don’t assume the same lanes are affected next time.
Source: Caltrans District 4 official closure notice, published September 9, 2026 (dot.ca.gov).