Twin Peaks Tunnel

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Twin Peaks Tunnel
Twin Peaks Tunnel.jpg
Twin Peaks Tunnel at Forest Hill station
Location San Francisco, California
Coordinates East portal:
37°45′43″N 122°26′13″W / 37.76194°N 122.43694°W / 37.76194; -122.43694
West portal:
37°44′29″N 122°27′56″W / 37.74139°N 122.46556°W / 37.74139; -122.46556
System Muni Metro
Start Eureka Station (closed)
End West Portal Station
No. of stations 3
(2 open, 1 closed)
Opened February 3, 1918; 100 years ago (1918-02-03)
Owner San Francisco Municipal Transportation Agency
Operator San Francisco Municipal Railway
Character Underground subway tunnel for light rail/streetcar system
Line length 2.27 mi (3.65 km)
No. of tracks 2
Track gauge 4 ft 8 12 in (1,435 mm) (standard gauge)
Electrified Overhead lines, 600 V DC
Tunnel clearance 25 ft (7.6 m)[1]
Route map

original portal
demolished c. 1970s
Market Street portal
never used
closed 1972
Forest Hill
West Portal
K Ingleside L Taraval M Ocean View
Inbound K Ingleside: sign changes to T Third Street

The Twin Peaks Tunnel is a 2.27-mile (3.65 km) long[1] light rail/streetcar tunnel in San Francisco, California. The tunnel runs under the Twin Peaks and is used by the K Ingleside/T Third Street, L Taraval, M Ocean View, and S Shuttle lines of the Muni Metro system.

History and background[edit]

The (now replaced) east portal of the Twin Peaks Tunnel in February 1967

The tunnel was opened on February 3, 1918,[1] and was the world's longest of its kind at the time.[2] The eastern entrance to the tunnel is located near the intersection of Market and Castro streets in the Castro neighborhood, and the western entrance is located at West Portal Avenue and Ulloa Street in the West Portal neighborhood. There are two stations along the tunnel, Forest Hill near the western end, and the now disused Eureka station near the eastern end.

When the Muni Metro system and Market Street Subway were built, they were connected to the Twin Peaks Tunnel to be used by the K Ingleside, L Taraval and M Ocean View lines. The Eureka station was closed, and the Metro lines stop at the nearby Castro Street Station instead.The original eastern entrance to the tunnel in the middle of Market Street at Castro was removed and new entrances were placed on the sides of the street further up the block, though no Metro or streetcar lines use them in regular service (they were used during construction of the Market Street subway and are occasionally used in non-revenue service such as rerouting trains around construction projects). Instead, trains continue directly from the Market Street Subway into the tunnel without going above ground.

The former West Portal streetcar stop in 1967, prior to conversion to light rail.

Forest Hill and Eureka stations were originally constructed with low platforms, as streetcars of that era had steps to load passengers from street level. However, the six new Market Street Subway stations were built with high-level platforms for speedier level boarding onto the new Boeing LRVs. West Portal station, which was originally a surface stop outside of the tunnel's western entrance, was rebuilt as a high-platform station located just inside of the entrance. With Eureka station permanently closed, Forest Hill was left as the only low-platform station on the Muni Metro subway. Muni soon modified the station with high-level platforms, with completion in 1985.[3]

Rail replacement project[edit]

Around 2014, with the tunnel nearing a century of continuous use, Muni began planning a major track replacement project in the tunnel - the first since 1975,[4] the project includes the replacement of all rails and ties in the tunnel with new rails directly fixed to concrete pads, the installation of two pairs of crossovers (one near West Portal, the other just east of Forest Hill), replacement of existing switches to the unused eastern portals, a structural refit of the former Eureka station area, replacement of the overhead wires, and a number of other repairs and improvements.[5] The work will lift an existing 25 miles per hour (40 km/h) speed limit through the tunnel. Noise reduction techniques from a similar project on the Sunset Tunnel in 2016 will be used.[6]

West Portal station, the western tunnel entrance, seen in 2017.

The construction contract was awarded on April 5, 2016,[4] the project was originally planned to begin in late 2016, but has suffered a series of delays. It was delayed from April 2017 to mid-2017 (with a completion date of mid-2018) in March 2017 to allow for "additional technical analysis" of the tunnel;[7] in June 2017, the project was indefinitely delayed after the construction contract was terminated.[8] Muni and the contractor could not agree on a new schedule and costs to minimize disruptions to riders; the project duration increased from 460 days to 807 days and the cost to $48 million, and Muni staff recommended the contract be terminated.[9] The SFMTA released a Request for Qualifications in October 2017, and bidding opened for the $35.5 million project in November.[10][11]

The closure began on June 25, 2018 and is expected to last until August 24. Muni Metro surface is short turned at Castro station; the surface section of the K Ingleside is through-routed with the J Church, while the L Taraval and M Ocean View are replaced by buses.[12]

See also[edit]


  1. ^ a b c Wallace, Kevin (March 27, 1949). "San Francisco History - City's Tunnels". San Francisco Chronicle. Retrieved July 14, 2008. 
  2. ^ "Twin Peaks tunnel opens". San Francisco Chronicle. February 4, 2009. Retrieved February 1, 2018. 
  3. ^ "Chapter 1". Muni Metro Turnaround Project: Final Enivironmental Impact Statement. United States DEpartment of Transportation Urban Mass Transportation Administration. August 1989. p. 1-2 – via Internet Archive. 
  4. ^ a b "Twin Peaks Tunnel Contract Awarded" (Press release). San Francisco Municipal Transportation Agency. April 28, 2016. 
  5. ^ San Francisco Planning Department (February 13, 2015). "CEQA Categorical Exemption Determination" (PDF). San Francisco Municipal Transportation Agency. pp. 5–6. 
  6. ^ "Twin Peaks Tunnel Improvements". San Francisco Municipal Transportation Agency. Retrieved November 30, 2017. 
  7. ^ "Twin Peaks Tunnel Construction Held Until Summer" (Press release). San Francisco Municipal Transportation Agency. March 16, 2017. 
  8. ^ "Twin Peaks Tunnel Construction Delayed" (Press release). San Francisco Municipal Transportation Agency. June 6, 2017. 
  9. ^ Chinn, Jerold (January 16, 2018). "Years of delay haunt Muni tunnel projects". SFBay. 
  10. ^ "Bid Document". City and County of San Francisco. October 17, 2017. 
  11. ^ "Bid Document". City and County of San Francisco. November 2017. 
  12. ^ "Twin Peaks Tunnel Improvements". San Francisco Municipal Transportation Agency. June 25, 2018. Archived from the original on June 26, 2018. 

External links[edit]

Media related to Twin Peaks Tunnel at Wikimedia Commons