Eureka Valley landscape from above Corbett Road showing terrain and road layout with proposed tunnel locations

Twin Peaks Tunnel

Twin Peaks Tunnel San Francisco: Visiting Hours, Tickets, and Historical Significance

Date: 14/06/2025

Introduction

The Twin Peaks Tunnel is an engineering marvel and a cornerstone of San Francisco’s urban development. Conceived in the early 20th century, it overcame the natural barrier of the Twin Peaks hills, connecting downtown San Francisco to its western neighborhoods. Since opening in 1918, the tunnel has transformed the city’s landscape, spurred economic growth, and stands as a symbol of resilience and modernization following the 1906 earthquake (SFMTA; FoundSF).

Today, the tunnel remains vital for the Muni Metro system, serving over 80,000 passengers daily on the K Ingleside, M Ocean View, and L Taraval lines. While direct access inside the tunnel is restricted to operational transit, visitors can explore its historic portals and the vibrant neighborhoods nearby. This guide offers a comprehensive overview of the tunnel’s history, engineering significance, practical visiting tips, accessibility, and nearby attractions.

Eureka Valley view from slopes above Corbett Road showing terrain and tunnel proposal locations

Contour study showing possible tunnel alignments at different depths below street surface for Plan 5B

Contour study of tunnel alignment showing possible alignments at different depths below street surface for Plan 5B

Perspective sketch of Eureka Valley showing Market Street extension and Eureka Valley station

Perspective view of Laguna Honda station showing open cut construction for transfer facilities and extension of Seventh Avenue down the Peninsula

Perspective view of Laguna Honda station with open cut construction and transfer facilities

Eureka Valley station high level project with island platform and center entrances on Market Street contour extension

Eureka Valley station island platform with center entrances and high-level project features

Laguna Honda station first construction stage with escalator and ramp entrances

Laguna Honda station first stage escalator and ramp entrance arrangement

Laguna Honda station second stage tunnel and local car station section diagram with direct transfer facilities

Section drawing of Laguna Honda station second stage showing tunnel center line and local car station with direct transfer facilities

Laguna Honda station second stage cross-section showing tunnel center line and superimposed local car station with direct transfer facilities

Typical arch and flat roof sections of rapid transit tunnel showing clearance lines and lining specifications

Diagram of typical arch and flat roof sections of rapid transit tunnel with clearance lines for rolling stock

Typical arch and flat roof sections of rapid transit tunnels with clearance lines

Arthur Scholz rendering of Twin Peaks Tunnel portal in 1910

Double tube flat top section engineering drawing from 1916

Tunnel section in soft ground showing construction details

Speakers at the Merchants' Association banquet May 1909 San Francisco

Original east portal of the Twin Peaks Tunnel at Castro Street in 1959

Historical map showing six alternative streetcar routes for the N Judah line through San Francisco's Sunset District in 1924

Illustration of Twin Peaks and eastern portal in San Francisco, March 1912

Early Urban Challenges and the Need for the Tunnel
Planning and Construction
Dedication and Opening Ceremonies
Impact on Urban Development
Technological and Engineering Significance
Evolution and Modernization
Visiting Information: Hours and Tickets
Guided Tours and Special Events
Nearby Attractions and Travel Tips
Accessibility Information
Cultural and Historical Legacy
Frequently Asked Questions (FAQ)
Plan Your Visit
References

1. Early Urban Challenges and the Need for the Tunnel

In the early 1900s, San Francisco’s west side was isolated due to the imposing Twin Peaks hills. Existing streetcar lines offered indirect, slow service, leaving nearly 4,000 acres undeveloped (SFMTA). The city’s rapid growth after the 1906 earthquake and a pressing need for affordable housing fueled public debate for a direct transit solution. By 1914, plans and funding for a tunnel connecting downtown to the western districts were finalized (FoundSF).

2. Planning and Construction

The Twin Peaks Tunnel was an ambitious project for its era, designed to be the world’s longest municipal tunnel upon completion. Spanning approximately two miles (3.2 km), it connected the Castro District at Market Street to the newly established West Portal neighborhood.

Construction began in 1914 under City Engineer M.M. O’Shaughnessy, utilizing steam shovels, manual labor, and dynamite. The central section beneath the hills was excavated by hand, while a rail conveyor system removed debris, particularly near Diamond Street. The construction process was meticulously documented, including in a film by the Pathescope company, which also chronicled the development of nearby neighborhoods (FoundSF).

3. Dedication and Opening Ceremonies

By mid-1917, the tunnel was completed. On July 14, 1917, Mayor James Rolph and City Engineer O’Shaughnessy marked the ceremonial completion at West Portal Avenue and Ulloa Street (SFMTA). The first streetcar journey occurred in early 1918, with crowds celebrating the city’s commitment to modern transit and urban growth.

4. Impact on Urban Development

The tunnel immediately catalyzed the transformation of neighborhoods like West Portal, Forest Hill, Stern Grove, and St. Francis Wood, which evolved from sparsely populated areas into thriving communities. The direct transit connection spurred residential and commercial development, profoundly shaping the city’s demographic and economic patterns (SFMTA; FoundSF).

5. Technological and Engineering Significance

Upon completion, the Twin Peaks Tunnel was a municipal engineering milestone: nearly 12,000 feet long, 25 feet in diameter, and designed for two tracks (SFMTA PDF). The Beaux-Arts West Portal station became an architectural landmark. The tunnel’s construction set new standards for urban transit projects and inspired future infrastructure developments (FoundSF).

6. Evolution and Modernization

The tunnel’s role evolved with the city’s transit needs. In the 1970s, it was integrated with the Market Street Subway, and both portals were reconstructed. Today, the tunnel accommodates the K, L, and M Muni Metro lines, serving over 80,000 daily riders (SFMTA). Ongoing upgrades, including seismic reinforcements and track replacements, ensure its reliability and safety (SFMTA Travel Updates).

7. Visiting Information: Hours and Tickets

Operating Hours: The tunnel operates daily as part of the Muni Metro system, with trains running from approximately 5:00 a.m. to midnight (SFMTA Official Site).
Tickets and Fares: Standard Muni fares apply (as of 2024, $3.00 for a single adult ride), with passes available for frequent riders.
Access: Experience the tunnel by riding the K, L, or M lines. Tickets can be purchased at station kiosks, via the MuniMobile app, or with Clipper cards.

Please note: The tunnel itself is not open for pedestrian tours due to operational and safety reasons.

8. Guided Tours and Special Events

While tours inside the tunnel are not available, the West Portal neighborhood hosts community and historical events that highlight the tunnel’s significance. The San Francisco Transit Museum and local history groups occasionally offer programs focusing on the city’s transit heritage, including the Twin Peaks Tunnel.

9. Nearby Attractions and Travel Tips

West Portal Neighborhood: Explore shops, cafes, and the historic West Portal Station.
Twin Peaks Viewpoint: Offers panoramic city views; accessible by car, bus, or a moderate uphill walk.
Forest Hill Station: Retains early 20th-century architectural features.
Stern Grove: A scenic park known for free summer concerts.

Travel Tips:

Use public transit to avoid parking challenges.
Mid-morning or early afternoon visits are less crowded.
The West Portal entrance is a favorite spot for photography enthusiasts.

10. Accessibility Information

Stations at West Portal and Castro are fully accessible, with elevators, ramps, and tactile paving. Muni Metro vehicles offer low-floor boarding for wheelchair and stroller access. For detailed accessibility guidance, visit the SFMTA Accessibility Guide.

11. Cultural and Historical Legacy

The tunnel’s story is preserved through archival films, photographs, and museum exhibits, with centennial celebrations marking its enduring place in San Francisco history. The original construction film is housed at the Niles Essanay Silent Film Museum, supported by preservation efforts (FoundSF). Community events continue to honor its legacy (SFMTA).

12. Frequently Asked Questions (FAQ)

Q: What are the Twin Peaks Tunnel’s operating hours?
A: The tunnel is open for transit service from about 5:00 a.m. to midnight daily.

Q: Can I walk through the tunnel or take a guided tour inside?
A: No, the tunnel is an active transit corridor and not open to pedestrians or tours.

Q: How do I visit or experience the tunnel?
A: Ride the Muni Metro K, L, or M lines through the tunnel; visit the West Portal and Castro neighborhoods for historic views and nearby attractions.

Q: Is the tunnel accessible for people with disabilities?
A: Yes, stations are fully accessible, and Muni Metro trains accommodate wheelchairs and strollers.

Q: Are there any special events related to the tunnel?
A: Occasionally, community and SFMTA events highlight the tunnel’s history; check the SFMTA website and local listings for updates.