T Third Street

File:Northbound train on Islais Creek bridge, May 2019.JPG

The T Third Street's northern terminus is Chinatown station inside the Central Subway. Trains operate south below Stockton Street to Union Square/Market Street station, which offers a connection to Powell Street station as the line does not enter the Market Street subway. The line then tunnels underneath 4th Street to serve Yerba Buena/Moscone station in the SoMA district before surfacing south of the Interstate 80 bypass, where it serves a stop at the 4th and Brannan station. The T then crosses the existing N tracks at 4th and King and continues south to 3rd Street. Additional short turn service between Chinatown and Mission Bay Loop will be later added.{{Cite web |last=Rodriguez |first=Joe Fitzgerald |date=2018-07-23 |title=Cost for long delayed Muni 'loop' to boost Warriors train service jumps $1.4 million |url=http://www.sfexaminer.com/long-delayed-muni-loop-boost-warriors-train-service-jumps-1-4-million/ |access-date=2018-10-23 |website=San Francisco Examiner}}{{Cite report |url=https://www.sfmta.com/sites/default/files/reports-and-documents/mission_bay_loop_environmental_assessment_may_2013.pdf |title=Environmental Assessment for Mission Bay Transit Loop Project |last=SFMTA |date=2013-05-06 |access-date=2018-10-23}} The line runs south through the Mission Bay neighborhood in a dedicated median, passing the Mission Bay Loop between 18th and 19th Streets, which is used to allow trains to turn around at Mission Bay or to hold special trains to serve events at Chase Center.

The line continues south through Dogpatch and across Islais Creek into the Bayview and Hunters Point neighborhoods. It runs in mixed traffic for {{convert|1/2|mile}} from Kirkwood Avenue to Shafter Avenue, then returns to dedicated lanes. A wye, occasionally used for short turning trains, is located at Armstrong Avenue. The line crosses the U.S. Route 101 freeway, where Third Street becomes Bayshore Boulevard, and continues south in the median. The southern terminus of the line is at Sunnydale station in the Visitacion Valley neighborhood.

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The T Third operates seven days a week, beginning at 5 a.m. weekdays, 6 a.m. Saturdays and 8 a.m. Sundays, operating until 1 a.m. Service is provided by the {{Muni route|91 Owl}} overnight bus during the hours that rail service is not running. On weekends, T Third Street Bus service runs from 5am until the start of rail service. The bus line largely follows the rail line, but it uses surface streets to parallel sections where the rail line has dedicated rights-of-way.

Third Street (and its extensions south) had streetcar service operated by the Market Street Railway until 1941, when repaving allowed the transit operator to replace the line with buses.{{cite news |title=Board Clears Way For Third Street Improvement |url=https://www.newspapers.com/article/the-san-francisco-examiner-board-clears/149335311/ |access-date=14 June 2024 |newspaper=The San Francisco Examiner |via=Newspapers.com |date=January 28, 1941 |location=San Francisco, California |page=4}} {{free access}}{{cite news |title=City Moves to Hasten Paving of Howard Street |url=https://www.newspapers.com/article/the-san-francisco-examiner-city-moves-to/149335471/ |access-date=14 June 2024 |newspaper=The San Francisco Examiner |via=Newspapers.com |date=March 11, 1941 |location=San Francisco, California |page=3}} {{free access}} The 15 Third Street bus was discontinued with the beginning of light rail service.{{Cite news |last=Rachel Gordon |date=April 9, 2007 |title=S.F.'s New T-Third Streetcar Line Hits A Few Bumps |work=The San Francisco Chronicle (SFGATE) |url=http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2007/04/09/BAGM1P5BGI13.DTL&hw=Third+Street&sn=022&sc=322 |access-date=2010-02-01}}

File:Third Street Light Rail construction at Marin Street station, March 2005.jpg

Construction of the line was proposed in the late 1980s as plans for the redevelopment of the Mission Bay neighborhood were established. Construction took place in the mid-2000s. The line was constructed as the Third Street Light Rail Project. Testing on the line took place in summer 2006,{{Cite news |last=Gordon |first=Rachel |date=July 26, 2006 |title=Third Street seeing streetcars / Test runs for light-rail project begin at last |work=San Francisco Chronicle |url=http://www.sfgate.com/bayarea/article/SAN-FRANCISCO-T-Third-line-causing-delays-so-2589267.php |access-date=2013-12-15}} with limited service starting on January 13, 2007, and full service beginning on April 7, 2007.{{Cite news |last=Cabanatuan |first=Michael |date=January 12, 2007 |title=T-Third Muni line starts service Saturday |work=San Francisco Chronicle |url=http://www.sfgate.com/default/article/T-Third-Muni-line-starts-service-Saturday-2623955.php |access-date=2013-12-15}} T Third Street service was initially operated between Castro station and Sunnydale station. Following service changes on June 30, 2007, the T Third Street and the K Ingleside lines were interlined through the Market Street subway and Twin Peaks tunnels, resulting in a combined route from Balboa Park, through downtown, to the Visitacion Valley neighborhood.{{Cite news |last=Gordon |first=Rachel |date=June 4, 2007 |title=T-Third line causing delays, so officials consider new routes |work=San Francisco Chronicle |url=http://www.sfgate.com/bayarea/article/SAN-FRANCISCO-T-Third-line-causing-delays-so-2589267.php |access-date=2013-12-15}}

The Mission Bay Loop project, which added a short turn loop using 18th, Illinois, and 19th, was constructed to supplement the Central Subway project. The loop was originally designed in 1998 as part of the Third Street Light Rail project, but was deferred due to insufficient funding. A $3.5 million construction contract was issued in 2014.{{Cite news |date=September 18, 2014 |title=SFMTA board approves contract for Mission Bay loop project |work=San Francisco Examiner |url=https://www.sfexaminer.com/news/sfmta-board-approves-contract-for-mission-bay-loop-project/}} Construction started in July 2016 and was completed in 2019.{{Cite web |title=Mission Bay Loop |date=May 13, 2013 |url=https://www.sfmta.com/projects/mission-bay-loop |access-date=24 October 2018 |publisher=San Francisco Municipal Transit Agency}} Another loop at 25th and Illinois is proposed to increase short-line service frequency between Downtown and Dogpatch.{{Cite news |last=Swan, Rachel |date=October 19, 2018 |title=The T line has never lived up to its promise. Coming upgrades may not be enough to help |work=San Francisco Chronicle |url=https://www.sfchronicle.com/bayarea/article/The-T-line-never-lived-up-to-its-promise-Now-13306888.php |access-date=24 October 2018}}

File:UCSF Mission Bay station construction, March 24, 2019.JPG

The underground section of the line was closed west of Castro station from June 25 to August 24, 2018, due to the Twin Peaks Tunnel shutdown.{{Cite web |date=June 25, 2018 |title=Twin Peaks Tunnel Improvements |url=https://www.sfmta.com/projects/twin-peaks-tunnel-improvements-0 |archive-url=https://web.archive.org/web/20180626232234/https://www.sfmta.com/projects/twin-peaks-tunnel-improvements-0 |archive-date=June 26, 2018 |publisher=San Francisco Municipal Transportation Agency}} On August 25, 2018, at the conclusion of the shutdown, Muni began running permanently two-car trains on the K/T line (as had been used east of Castro during the shutdown).{{Cite press release |title=Two-Car Trains Now Permanent on K/T Line |date=August 24, 2018 |publisher=San Francisco Municipal Transportation Agency |url=https://www.sfmta.com/blog/two-car-trains-now-permanent-kt-line |last1=von Krogh |first1=Bonnie Jean}} The line was shut down again, from January 22, 2019, until April 1, 2019, for construction of a new platform at UCSF/Mission Bay station.{{Cite web |title=T Third Bus Substitution |url=https://www.sfmta.com/routes/t-third-bus-substitution |archive-url=https://web.archive.org/web/20190120045347/https://www.sfmta.com/routes/t-third-bus-substitution |archive-date=January 20, 2019 |publisher=San Francisco Municipal Transportation Agency}}{{Cite press release |title=T Third Back In Action |date=March 29, 2019 |publisher=San Francisco Municipal Transportation Agency |url=https://www.sfmta.com/blog/t-third-back-action |last1=McMillan |first1=Erin}} In April 2019, the SFMTA ended the use of unscheduled short turns. These had been used to provide more consistent service on the inner portion of the line, but had caused inconsistent and less frequent service in the Hunters Point-Bayview and Visitacion Valley neighborhoods.{{Cite press release |title=SFMTA to Stop Switching Back Trains on the T Third Line |date=April 9, 2019 |publisher=San Francisco Municipal Transportation Agency |url=https://www.sfmta.com/sites/default/files/reports-and-documents/2019/04/sfmta_-_press_release_-_sfmta_to_stop_switching_back_trains_on_the_t_third_line.pdf}}

On March 30, 2020, Muni Metro service was replaced with buses due to the COVID-19 pandemic.{{Cite press release |title=Starting March 30: New Muni Service Changes |date=March 26, 2020 |publisher=San Francisco Municipal Transportation Agency |url=https://www.sfmta.com/blog/starting-march-30-new-muni-service-changes |last1=Fowler |first1=Amy}} Rail service returned on August 22, with the routes reconfigured to improve reliability in the subway. T Third Street and M Ocean View light rail lines were interlined, running between Sunnydale station and Balboa Park station.{{Cite press release |title=Major Muni Service Expansion August 22 |date=August 18, 2020 |publisher=San Francisco Municipal Transportation Agency |url=https://www.sfmta.com/blog/major-muni-service-expansion-august-22 |last1=Maguire |first1=Mariana}} Light rail service was re-replaced with buses on August 25 due to issues with malfunctioning overhead wire splices and the need to quarantine control center staff after a COVID-19 case.{{Cite press release |title=Effective August 25 Buses Serve Muni Metro Routes |date=August 25, 2020 |publisher=San Francisco Municipal Transportation Agency |url=https://www.sfmta.com/blog/effective-august-25-buses-serve-muni-metro-routes |last1=Dunn |first1=Bradley |access-date=November 28, 2021}} Rail service resumed on the Embarcadero–Sunnydale section of the T Third Street line on January 23, 2021.{{Cite press release |title=Upcoming Muni Service Expansions Phase-in Rail Service, Add Bus Service |date=December 7, 2020 |publisher=San Francisco Municipal Transportation Agency |url=https://www.sfmta.com/blog/upcoming-muni-service-expansions-phase-rail-service-add-bus-service |last1=Maguire |first1=Mariana}} In preparation for the return of rail service, several temporary changes were made at the 4th Street bridge over China Basin: one southbound lane became a transit-only lane, and a northbound turn lane at Berry (which shared space with the tracks) was removed.{{Cite press release |title=4th Street Bridge Temporary Emergency Transit Lanes Approved |date=January 11, 2021 |publisher=San Francisco Municipal Transportation Agency |url=https://www.sfmta.com/blog/4th-street-bridge-temporary-emergency-transit-lanes-approved |last1=McMillan |first1=Erin}} This change was found to decrease delays at the bridge by 60%.{{Cite web |last1=Kirschbaum |first1=Julie |last2=Kennedy |first2=Sean |title=Transit Update |url=https://www.sfmta.com/sites/default/files/reports-and-documents/2021/04/4-20-21_item_12_transit_update_-_slide_presentation.pdf |publisher=San Francisco Municipal Transportation Agency |page=20}} Service was re-extended to West Portal on May 15, again through-routed with the K Ingleside.{{Cite press release |title=Welcome Back to the Westside, K Ingleside Trains! |date=April 16, 2021 |publisher=San Francisco Municipal Transportation Agency |url=https://www.sfmta.com/blog/welcome-back-westside-k-ingleside-trains}}

As part of the January 2021 service change, Muni also added the 15 Bayview-Hunters Point Express bus route. The route makes local stops in the Bayview–Hunters Point neighborhood east of Third Street and limited stops on Third Street paralleling the T.{{cite press release |url=https://www.sfmta.com/blog/150-year-history-munis-%E2%80%98newest-route-15 |title=The 150 Year History of Muni's 'Newest' Route: The 15 |date=April 7, 2021 |first=Jeremy |last=Menzies |publisher=San Francisco Municipal Transportation Agency}}{{cite press release |url=https://www.sfmta.com/blog/muni-expands-service-access-equity-neighborhoods-january |title=Muni Expands Service, Access for Equity Neighborhoods in January |date=January 20, 2021 |first=Mariana |last=Maguire |publisher=San Francisco Municipal Transportation Agency}}

{{Main|Central Subway (San Francisco)}}

The second phase of the line was built as the Central Subway, which forms a crosstown link between South of Market (SoMa) and Chinatown via Union Square. Voters approved the Central Subway in 2003, and the alignment was selected in 2008.{{Cite web |title=MTA Board Selects Central Subway Alignment |date=February 20, 2008 |url=http://transbayblog.com/2008/02/19/mta-board-selects-central-subway-alignment/ |access-date=February 21, 2008 |publisher=Transbay Blog}}{{Cite news |last=Nevius, C.W. |date=April 22, 2013 |title=The hole in subway opponents' arguments |work=San Francisco Chronicle |url=http://www.sfgate.com/bayarea/nevius/article/The-hole-in-subway-opponents-arguments-4449461.php |access-date=December 6, 2017}} Construction began in 2012.{{Cite news |last=Cabanatuan, Michael |date=June 11, 2012 |title=S.F. Central Subway tunnel construction to begin |work=San Francisco Chronicle |url=http://www.sfgate.com/bayarea/article/S-F-Central-Subway-tunnel-construction-to-begin-3623724.php |access-date=December 6, 2017}} After numerous delays, the Central Subway opened on November 19, 2022, with a weekend-only shuttle service operating between {{munis|Chinatown}} and {{munis|4th and Brannan}}. The T Third Street was rerouted to travel through the Central Subway for full service on January 7, 2023.{{cite press release |url=https://www.sfmta.com/travel-updates/central-subway-service-changes |title=Central Subway Service Changes |date=November 19, 2022 |publisher=San Francisco Municipal Transportation Agency}}{{Cite press release |title=Central Subway Opens November 19 with Special Weekend Service |date=November 1, 2022 |publisher=San Francisco Municipal Transportation Agency |url=https://www.sfmta.com/blog/central-subway-opens-november-19-special-weekend-service}}{{cite news |last1=Bay City News |title=New Central Subway Line Opens in San Francisco |url=https://www.nbcbayarea.com/news/local/central-subway-line-san-francisco/3123506/ |access-date=January 7, 2023 |work=KNTV |publisher=NBC Owned Television Stations |date=January 7, 2023|author1-link=Bay City News }} Service runs every 10 minutes on weekdays and every 12 minutes on weekends. Shuttle trains signed "S Mission Bay" operate between {{munis|Chinatown}} and {{munis|UCSF/Chase Center}} for events at Chase Center.{{cite press release |url=https://www.sfmta.com/blog/new-t-third-route-central-subway-starting-january-7 |title=New T Third Route in Central Subway Starting January 7 |date=December 13, 2022 |first=Mariana |last=Maguire |publisher=San Francisco Municipal Transportation Agency}}

The Central Subway was closed from February 26 to March 14, 2025, for water leakage mitigation at Chinatown station. T Third Street service was again interlined with K Ingleside service.{{cite press release |url=https://www.sfmta.com/blog/central-subway-close-feb-26-march-14-what-were-fixing-and-how-get-around |title=Central Subway to Close Feb. 26 - March 14: What We're Fixing and How to Get Around |date=February 20, 2025 |first=Amy |last=Fowler |publisher=San Francisco Municipal Transportation Agency}}

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{{collapse top|title=Diagrams of the various T Third Street routings over its history:}}

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All stations along this line feature high platforms, eliminating the need for the raising and lowering of entrance and exit steps characteristic of other Muni Metro lines.

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• [https://www.sfmta.com/routes/kt-k-inglesidet-third-street SFMTA - K Ingleside/T Third Street]

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Category:Muni Metro lines

Category:2007 establishments in California