Сан-Францисконың "Сансет" тоннелі: Тарихы мен жаңарту жобасы

Streetcar tunnel in San Francisco, California, U. S.
the Oregon highway tunnel formerly known as the Sunset Tunnel

Funds for test bores were set aside in June 1922 and the City Engineer's report, including detailed plans and estimated costs, were filed three months later in September. As planned, the tunnel would be 4250 feet (1295 m) long and would cost $1500000. The final route was not approved until April 6, 1925, due to "protracted political discussion." As designed, the Sunset Tunnel was 4232 feet (1290 m) long including approaches with a grade of 3%; inside, the width was 25 feet (8 m) and the vertical clearance was 18 feet (5 m) above the top of the rail. Construction of the tunnel was completed on February 4, 1928 for a total cost of $1477618. After the tunnel was nearly complete, a contract was awarded to build the rail line, but work was halted under an injunction that lasted from October 1927 to May 1928. The tunnel was opened for revenue service on October 21, 1928 in a ceremony presided over by Mayor James Rolph. The new "N" line recorded the second highest gross revenues of all streetcar lines shortly after opening. Both the Twin Peaks and Sunset tunnels were credited with spurring development in the Sunset District, with many of the homes built by Henry Doelger in the 1930s and 1940s.

Access to the tunnel is restricted to San Francisco Municipal Railway light rail trains only. Despite the access limitations, this tunnel is not well protected, and has been vandalized, copper cable has been stolen, and graffiti has been painted on the surfaces. From time to time, automobile drivers manage to drive their cars into the tunnel, including four separate incidents in February 2017 alone.

The Sunset Tunnel Trackway Improvement Project replaced tracks and repaired key equipment inside the tunnel, including a new overhead contact system, fire sprinkler valve refurbishment, seismic upgrades, and rebuilt platforms at 28th Avenue. The work, which started in November 2014, was originally planned to finish by June 2015, but was not completed until October 2017. During some weekends, the tunnel was closed and N Judah was short turned at Church & Duboce. Buses were used to continue service to Ocean Beach. A combination of additional needed work that was discovered during construction, plus nearby residents challenging a night work permit, resulted in delays to the project and an additional $4 million cost for a total of $23.3 million.