Attn: 1 Muni elevators out of service; Civic Center Bart Elevator

Twin Peaks Tunnel Improvements

With 100 years of service under its belt, Twin Peaks Tunnel needs extensive work to its interior to continue to operate safety and reliably for years to come. The tunnel's infrastructure, including the tracks, walls and drainage systems, must be maintained in a timely manner to keep up with the demands of the Muni system. Twin Peaks Tunnel is currently under a speed restriction, which slows down trains as they travel through. Replacing the tracks will lift the tunnel's speed restriction and keep trains running reliably through the system. Seismic reinforcements will better protect the tunnel's overall structure and stability.  Construction is expected to start in summer 2018 during a continuous closure of the tunnel up to 60 days.

Project Timeline 
Present - Summer 2018
Summer 2018
January 2019
Final Design and Pre-Construction
Project Completion
Cost Estimate 
$40 million
Current Phase or Stage 
Final Design
Predicted Completion 
Winter 2019
Project Status 
Project Success 
On budget
On schedule
SFMTA Muni Metro train icon
New tracks and improved tunnel infrastructure
West Portal Avenue, Market Street, Junipero Serra Boulevard, Ulloa Street, Collingwood Drive

    Weekend Overnight Closures

    On weekend evenings and mornings now through June 2018, there will be preparatory work taking place inside Twin Peaks Tunnel ahead of the summer closure. In order to allow this vital work to take place, stations will close early on Friday and Saturday nights. Buses will run in place of the K, L and M lines during closures of the Twin Peaks Tunnel.

    Weekend train service will operate normally from 9:00 a.m. to 11:00 p.m. on Saturdays and Sundays.

    K, L, M Bus Substitution and Tunnel Closures:

    • Friday nights from 11:00 p.m. to Saturday mornings at 9:00 a.m.
    • Saturday nights from 11:00 p.m. to Sunday morning at 9:00 a.m.

    Line Specific Rider information:

    Friday and Saturday nights, 11:00 p.m. – 5:00 a.m.

    • K, L and M buses will service all stops
    • Owl bus service will run as normal

    Saturday and Sunday mornings 5:00 a.m. – 9:00 a.m.

    • Going Inbound
      • L customers: L buses will service all stops from SF Zoo to Embarcadero
      • K customers: ride a K bus to West Portal and transfer to L or KLM Bus
      • M customers: ride an M bus to West Portal and transfer to L or KLM Bus
    • Going Outbound
      • L customers: L or KLM bus will serve all stops Embarcadero to SF Zoo
      • K customers: ride an L or KLM bus to West Portal and then transfer to K bus
      • M customers: ride an L or KLM bus to West Portal and then transfer to M bus

    Customers can board all buses at Muni Shuttle route stops, designated with a "Muni Metro Shuttle" yellow half-moon sign.

    Getting Around on Muni During Construction

    While the tunnel is closed for construction, buses will run for the M Ocean View and L Taraval lines. K Ingleside trains will run a shorter route between Sloat/St. Francis and Balboa Park. There will not be K Ingleside, L Taraval or M Ocean View trains running in Muni Metro. 

    During weekday morning rush hour (6 a.m.-10 a.m.), Muni customers transferring to BART at Balboa Park can receive a free BART single-ride ticket, good for travel downtown through Embarcadero BART Station.

    Forest Hill and West Portal stations will be closed for service. All outbound trains entering Castro Station heading outbound will switch back and head inbound.

    Only S Shuttles and T Third trains will operate through Castro and Church stations. There will be increased service for N Judah, J Church, T Third and S Shuttle trains.

    K Ingleside trains 

    • Trains will serve regular stops between Sloat/St. Francis and Balboa Park. 
    • Customers headed downtown are encouraged to transfer to BART at Balboa Park.

    L Taraval buses

    • Buses will serve regular stops between the zoo and Taraval & 17th Avenue. 
    • Temporary bus stops will be at the following locations for inbound and outbound directions:
      • Taraval & 14th Avenue (transfer stop for 48 bus)
      • Taraval & Wawona (closest stop to West Portal Station)
      • Dewey & Laguna Honda (closest stop to Forest Hill Station)
      • Woodside & Portola (transfer stop for 36, 44, 52 and M buses)
    • All L buses will end at Castro Station. Customers heading downtown can transfer to shuttle trains at the station.
    • L buses will not stop at West Portal Station. Customers can transfer to M buses at Woodside & Portola for M buses headed towards West Portal.
    • L buses will not service the following stop locations:
      • 15th Avenue & Taraval- closest stop is 14th Ave & Taraval
      • Ulloa & Forest Side
      • West Portal Station
    • Bus frequency: every 5 minutes during peak hours, 8-15 minutes during midday and evening

    M Ocean View buses

    • Buses will serve regular stops between San Jose & Geneva and 19th Ave & Winston, at Right of Way/Ocean Ave, and between West Portal & Sloat and West Portal & Vicente.
    • Temporary bus stops will be at the following locations for inbound and outbound directions:
      • Junipero Serra & Ocean (transfer location to K trains)
      • Portola & Laguna Honda (transfer location for 43 and 48 buses)
      • Woodside & Portola (transfer location for 36, 44 and 52 buses)
    • All M buses will end at Church Station. Customers heading downtown can transfer to shuttle trains in the station.
    • M buses will not stop at Forest Hill or Castro stations Customers can transfer to L buses at Woodside & Portola to reach these stations.
    • M Buses will not service the following stops:
      • Right of Way/Eucalyptus Drive- closest stops at Right of Way/Ocean Ave or 19th Ave/Winston 
      • West Portal Station- closest stop at West Portal & Vicente
      • Forest Hill Station
      • Castro Station
    • Bus frequency: every 5 minutes during peak hours, 8-15 minutes during midday and evening

    Forest Hill Shuttle Bus

    The Forest Hill Shuttle Bus will connect between L and M buses and K trains, running every 15 minutes. The shuttle will stop at the following locations:

    • Forest Hill Station
    • Dewey & Laguna Honda
    • West Portal & Vicente
    • West Portal & 15th Ave
    • Sloat/St. Francis

    OWL Service 

    L OWL and 91 OWL buses will be rerouted via 14th Ave and Vicente. Transfer between 91 and L buses at West Portal Ave & Vicente.

    Nx Express Service

    Buses will not operate during tunnel construction. Use N trains instead.


    Project video(s) 
    Project Details, History or Features 

    SFMTA will be working in the tunnel to address the following improvements:

    • Replacing the existing light rail tracks and track fittings
    • Replacing the machines which operate the track switching mechanisms
    • Replacing the tunnel's drainage system
    • Adding crossover tracks for operation flexibility
    • Seismic upgrades to the original east portal of Twin Peaks Tunnel (Eureka Valley Station)
    • Improving structure support between West Portal and Forest Hill stations
    • Improvements to fire suppresion system at West Portal Station
    • Repairing areas on concrete walls and reinforcements

    Construction Staging

    Staging areas on both sides of the tunnel will be used to store materials and equipment, and ensure that crews have the nessesary materials at hand to work quickly and efficienty.

    The staging area on the West Portal side of the tunnel will be on Junipero Serra between Sloat Boulevard and Ocean Avenue, along both sides of the K Ingleside Muni tracks (see image below). The staging area will not affect transit and vehicle traffic-- trains will run regular service and Junipero Serra will maintain existing traffic lanes. To accommodate the staging area, parking on the east and west sides of Junipero Serra will be temporarily removed until construction is complete.

    The MTA-owned parking lot located at Ocean Avenue and Junipero Serra will also be used for storing vital materials and equipment for the duration of construction. Streets around the parking lot will remain open and accessible.

    Median space along K Ingleside tracks on Junipero Serra between Ocean and Sloat will be used for staging during the construction. The Lakeside Parking Lot at the corner of Ocean and Junipero Serra will also be used for storage and staging until construction is complete.                                                                                                                                                                                                                                                                                                                                                                                                   

    On the Castro side of the tunnel, the areas in front of the original Twin Peaks Tunnel portals on Market Street will be used as a staging area (see image below). Bus stops affected by the staging area will be temporarily relocated during construction. The right turn onto Market Street from Collingwood Street will not be accessible. Vehicles on Collingwood headed to Market Street would need to turn onto 18th Street and Castro Street. All sidewalks and pathways leading to Castro Muni station will remain open to pedestrians.​

    Staging area is along Market Street between Collingwood and Castro, outside of the original tunnel portals

    Twin Peaks Tunnel History

    Twin Peaks Tunnel was a vital component to the growth of San Francisco and the expansion of the Muni system. After the 1906 earthquake, San Francisco's infrastructure developments grew, and city officials looked to expand the growth to the outer areas of the city, especially the undeveloped land west of Twin Peaks. In order to effectively reach the west side, city engineer Michael O’Shaughnessy decided to drill straight through the mountains. In February 1918, the Twin Peaks Tunnel opened, connecting the end of Market Street, at Eureka Valley station, to developing neighborhoods in Forest Hill and West Portal. K Ingleside and L Taraval shuttles began running soon after the tunnel opened. M Ocean View service began in 1925 and expanded as neighborhoods expanded. A bond issue passed in 1962 to build the regional BART system also included funding to build subway tunnels for Muni. The new Muni tunnels were connected to the Twin Peaks Tunnel, creating Castro station and providing a more streamlined service through the city. Today, Twin Peaks Tunnel carries over 80,000 Muni customers daily.

    Contact Information 
    Phillip Pierce