The Twin Peaks tunnel, connecting Castro Station with West Portal Station and used by Muni lines K, L, and M, will be undergoing significant construction in an upcoming SFMTA project.
According to a community mailer, details of the project include replacing all of the light rail tracks inside the tunnel with tracks that allow the trains to move faster, in order to improve transit schedules. "The Twin Peaks Tunnel is currently under a speed restriction, which slows down trains as they travel through," explains the SFMTA project website. "Replacing the tracks will lift the speed restriction and allow trains to move faster through the tunnel and speed up travel times."
A number of additional retrofits to the inside of the tunnel will happen at the same time as the track replacements. These will include seismic upgrades, concrete reinforcement repairs, and cleaning and repairing of the tunnel drainage system.
Details of the project, including construction timelines and staging areas, "are still being evaluated and are subject to change," according to the SFMTA, so there's no word yet on when the construction might begin.
In terms of neighborhood impacts, "Construction noise may be expected in West Portal and Castro neighborhoods near the tunnel entrances," states the SFMTA. "When the tunnel is closed, bus shuttles will be provided to bridge affected stations."
The project comes as weekend work on the Sunset Tunnel, connecting the N-Judah line between Cole Valley and Duboce Triangle, is currently underway.
If you'd like to learn more, there will be an open-house style meeting held tomorrow, March 26th, from 6pm-7:30pm at the Castro Community Meeting Room (501 Castro St.). Though there won't be an official presentation, locals are invited to hear information on the project and to ask additional questions or voice concerns.
The 2.27-mile tunnel originally opened on February 3rd, 1918, and is one of the world's longest streetcar or light-rail tunnels. Check out some interesting tunnel tidbits here.
And for a fascinating trip back in time, check out this silent film of the tunnel's construction, beginning in 1914. Developed by a local real estate firm of the time, the film was designed to encourage settlement of the West Portal area, and was apparently so popular when it was released in 1917 that it was continuously screened for weeks.