The Twin Peaks Tunnel has over a century of service under its belt and needs work to keep up with the demands of time and the Muni system. We conduct regular visual inspections and recently completed a comprehensive structural inspection of the tunnel. The inspection found that the tunnel is safe for both Muni passengers and workers, but two areas within the tunnel will require some immediate rehabilitation and repair work. We plan to complete these repairs this year over the summer.
After completing these repairs, the SFMTA will continue conducting regular inspections and structural evaluations of the tunnel, and expects to make additional improvements to the tunnel over the next 5-10 years to keep it safe and reliable for years to come.
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Construction Timing
The work this summer requires three separate closures of the tunnel:
- June 22-23 (weekend)
- July 20-21 (weekend)
- August 22-29 (eight days, Thursday-Thursday)
We are doing everything we can to keep the shutdown durations short and will work closely with riders, merchants, and residents to minimize any disruptions. The weekend closures in June and July will allow us to conduct trials of the tunnel repairs, with full repairs to be completed during the eight-day closure in August. This closure also allows us to consolidate the repair work with needed track maintenance, completing multiple projects at once and minimizing construction impacts.
Additionally, the San Francisco Unified School District will begin an improvement project at the West Portal Elementary School, which sits on top of the Twin Peaks Tunnel. We are working closely with SFUSD to coordinate work on the tunnel with their project schedule.
Muni Service Impacts
During construction, the subway will operate from Embarcadero to Castro, and we will run bus shuttles from Castro and Church to the outer rail terminals on the K, L, and M.
- West Portal and Forest Hill stations will be closed all day. Please use K, L or M bus shuttle substitutions on the surface.
- M Buses and K Buses will run between Balboa Park and Church, with stops at West Portal, Forest Hill, Castro and Church.
- L Buses will be extended to run between SF Zoo and Church, with stops at West Portal, Forest Hill, Castro and Church.
- S Shuttle trains will run extra service between Castro and Embarcadero stations, serving all stations in between.
- J, N and T trains will run as usual. Transfer between underground Muni Metro trains and K, L and M buses at Church or Castro.
| Route | Service Change Details | Planned Daytime Frequency |
|---|---|---|
| K Ingleside | Use K Ingleside Bus on the surface for all stops between Balboa Park and Church. For service downtown, transfer to/from S Shuttle train in the subway at Castro or Church. |
Weekdays: every 8 minutes Weekends: every 10 minutes |
| L Taraval | L Taraval Bus will be extended further east to Church, serving all stops between SF Zoo and Church. |
Weekdays: every 8 minutes Weekends: every 10 minutes |
| M Ocean View | Use M Ocean View Bus on the surface for all stops between Balboa Park and Church. For service downtown, transfer to/from S Shuttle train in the subway at Castro or Church. |
Weekdays: every 8 minutes Weekends: every 10 minutes |
| S Shuttle | S Shuttle trains will run extra subway service downtown between Castro and Embarcadero stations, serving all stations in between. Transfer to/from K, L and M buses at Castro or Church. |
Weekdays: every 6 minutes Weekends: every 6 minutes |
Construction Details
Grout will be injected to strengthen loose soil adjacent to the tunnel in two areas. Steel reinforcements within the tunnel walls in these areas will also be retrofitted with new steel tie-rods. Planned track maintenance work includes replacement of rail joints in the eastern part of the tunnel near the Eureka Valley station area of the tunnel.
After completing the work, we'll continue to inspect and monitor the tunnel, and longer-term rehabilitation work will be planned based on those findings.
Frequently Asked Questions
How was the construction schedule decided?
We recognize the eight-day closure from August 22-29 will be disruptive and will take place during the first week of school for many students. This was the only available week to perform this work due to several factors, including:
- Time needed for contracting, design, preparing materials, and crew availability meant this work could not happen until August.
- The SFUSD project in West Portal has construction planned for September, so our work couldn’t happen after August.
- Muni is a critical part of getting people to major special events in the city, and there are many large summer events we had to schedule around, such as Outside Lands, the Polo Fields Concert, and Baseball games (all attracting 30k - 70k people daily). The number of buses and operators required to operate bus shuttles during the tunnel closure is very high and does not leave enough remaining buses and operators to also support transportation to and from these events.
The weekend closures in June and July allowed us to conduct trials of the tunnel repairs and establish the best methods and materials for the full repairs during the eight-day closure in August.
We recognize that bus substitutions can be inconvenient. We have consolidated multiple rail projects to be completed at the same time as the Twin Peaks Tunnel structure work to minimize the total dates of bus substitutions.
How much extra time should I plan to get to my destination?
How long a Muni trip might take can vary widely due to differences in start and end points, time of day, traffic and other factors. Allowing an additional 15-30 minutes of travel time should be a safe average estimate, especially for the first trip as customers learn where to go and what to do.
Muni Ambassadors will be present at transfer points and other key locations to assist customers traveling during the tunnel closure. For some trips, the fastest travel time may be to use BART instead of Muni. See below for more info about trip planning.
Will real-time arrival predictions be available? Will I be able to use trip planner apps or websites?
The K Bus, L Bus, M Bus and S Shuttle will all have real-time predictions. You can find real-time route information and frequencies on our website by visiting the Muni route page.
Additionally, most transit planner apps will be updated to help customers plan their trips and get personalized travel time estimates during the shutdown. Trip planners can also provide detailed information about where to board the buses and transfer between buses and trains.
What are you doing to help students plan getting to and from schools?
We are working with SFUSD, universities and private schools to help get the message out about the bus substitutions and other Muni service changes to school families, especially new students. Families can learn more and sign up for information about nearby Muni routes for every school by visiting our Muni Routes to City Schools webpage.
As in past years, we will begin running “school trippers” service throughout the school year. These are extra afternoon buses on existing lines that begin their route at a school site, pick up students at the end of the school day (except on early dismissal days), then continue along the route as normal.
Additionally, our general outreach to the public during the tunnel closures includes ambassadors, signage at Muni Metro stations and along affected routes, multilingual handouts, digital displays and audio announcements at stations and on vehicles.
Will there be any parking impacts during the tunnel closures?
To accommodate a higher volume of buses, some parking will be temporarily restricted during the tunnel closures to create a longer bus stop at:
- Ulloa Street: South side between West Portal Avenue and Claremont Boulevard
Bus layover zones will temporarily replace parking in two locations near the K and M bus terminal areas for operators to switch shifts and take breaks between runs at:
- Market Street: North side between Sanchez and Church, from the fire hydrant at 2158 Market to Blackbird parklet (200 ft)
- San Jose Avenue: East side between Geneva and Seneca, from existing bus zone at Crazy Pepper to driveway at 2229 San Jose Ave (80 ft)
Will the buses carry the same number of people as the trains?
Muni’s trains are larger than Muni’s buses and can carry more people at one time. To carry the same number of people, smaller buses are scheduled to come more often than larger trains. On weekdays, riders will see buses come every 8 minutes for K Bus, L Bus, and M Bus, when trains usually come every 10 minutes. On weekends, riders will see buses come every 10 minutes for K Bus, L Bus, and M Bus, when trains usually come every 12 minutes.
To plan for this bus substitution, Muni’s Transit Planners analyzed how many people ride Muni’s trains at the busiest times on weekdays and weekends and how many “forty-foot” long buses and “sixty-foot” long buses would be required to carry everyone. Customers will see a mix of forty-footers and sixty-footers on the K Bus and M Bus lines.
