“All aboard” echoes faintly. Today at Sunset Tunnel Park, we uncover the story of a vital piece of San Francisco’s transportation history.
The Sunset Tunnel, originally the Duboce Tunnel, is more than just a passage. It’s a 4,232-foot-long light rail tunnel. The N Judah Muni Metro line exclusively uses it. Imagine a time before this tunnel existed. The Sunset District was far less accessible.
Bion J. Arnold proposed a Mission–Sunset Tunnel in 1913. His plan aimed to improve transportation from the Panhandle region. It would connect to the Market Street subway. The tunnel would also serve the Sunset District from the south of Market area.
However, the city prioritized the Twin Peaks Tunnel. It opened in 1918. Soon after, a Sunset Tunnel alignment along Duboce Avenue was proposed.
In 1921, the Board of Supervisors allocated funds. City Engineer M.M. O’Shaughnessy considered several routes. He preferred the Duboce route. The Board approved it in 1922. Sunset residents favored the shorter Duboce route.
Test bores began in June 1922. Plans detailed a 4,250-foot tunnel. The cost was estimated at $1,500,000. Final approval came in 1925 after political discussions.
The Youdall Construction Company won the contract in 1926. Construction started on June 10, 1926. The Sunset Tunnel included approaches with a 3% grade. It was 25 feet wide. Vertical clearance was 18 ft 9 in. The tunnel was largely through serpentine rock.
Workers used three drifts to build the tunnel. A pilot drift provided ventilation. It also explored geologic formations. The crown drift “holed-through” in March 1927. Construction concluded on February 4, 1928. The total cost was $1,477,618.
The Sunset Tunnel opened on October 21, 1928. Mayor James Rolph presided over the ceremony. The new “N” line quickly became popular. Both tunnels spurred development in the Sunset District. Many homes were built in the 1930s and 1940s.
Despite restricted access, the Sunset Tunnel has faced challenges. Vandalism, copper cable theft, and graffiti have occurred. Cars have even entered the tunnel accidentally.
A Trackway Improvement Project replaced tracks. It also repaired equipment inside. This included a new overhead contact system. Seismic upgrades were performed. Platforms at 28th Avenue were rebuilt. The project ran from 2014 to 2017.
Today, the Sunset Tunnel continues to serve San Francisco. It remains a vital transportation link. It symbolizes progress and perseverance. As you stand here at Sunset Tunnel Park, consider the history beneath your feet. The Sunset Tunnel’s story is a testament to San Francisco’s growth. It connects communities across the city.