T Third Street

The T Third Street is a Muni Metro light rail line in San Francisco, California. It runs along the east side of San Francisco — primarily in the median of Third Street — from to the Market Street subway. It is interlined with the K Ingleside line, forming a single service running between Sunnydale and . The line serves 21 surface stations, all of which are accessible. Most of the surface portion of the line runs in dedicated median lanes, though two portions operate in mixed traffic.

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. Limited service began in January 2007, with full service beginning in April of the same year. It was the first line added to the Muni Metro system since the N Judah in 1928.

In January 2023, the line will begin using the new Central Subway, a crosstown route from to . The Central Subway's weekend shuttle service between and Chinatown used since November 2022 and going until the main T Third Street switches over to the Central Subway presently brands its rolling stock as part of the T Third Street. From this point onward, the K Ingleside will no longer be interlined with the T Third Street.

Operations

Route

The T Third Street and K Ingleside are interlined, so trains run between and . Trains change designation when entering the Market Street subway: eastbound K trains become T trains at , and westbound T trains become K trains at . From Embarcadero, the tunnel curves southeast and reaches the surface at Ferry Portal near Folsom Street. The T (and N Judah) use tracks in the median of The Embarcadero and King Street, with several surface station. At 4th and King, the T separates from the N and turns south onto 4th Street. It crosses the 4th Street Bridge and uses a single block of Channel Street to reach Third Street. 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 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.

When the T is rerouted into the Central Subway in January 2023, it will no longer be interlined with the K, and will no longer use the Market Street subway or the surface tracks on Embarcadero and King. Instead, it will cross the N tracks at 4th and King and continue north in the median of 4th Street. It will enter the Central Subway under the I-80 viaduct and serve subway stations at , , and . Additional short turn service between Chinatown and Mission Bay Loop will be later added.

Service

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 overnight Owl buses during the hours that rail service is not running. The serves the portion between Embarcadero and 4th Street, and the serves the portion between 4th Street and Sunnydale. 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.

History

Construction

The line was constructed as the Third Street Light Rail Project. Testing on the line took place in summer 2006, with limited service starting on January 13, 2007, and full service beginning on April 7, 2007. 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.

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. Construction started in July 2016 and was completed in 2019. Another loop at 25th and Illinois is proposed to increase short-line service frequency between Downtown and Dogpatch.

Later changes

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. 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). 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. 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.

On March 30, 2020, Muni Metro service was replaced with buses due to the COVID-19 pandemic. 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. 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. Rail service resumed on the Embarcadero–Sunnydale section of the T Third Street line on January 23, 2021. 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. This change was found to decrease delays at the bridge by 60%. Service was re-extended to West Portal on May 15, again through-routed with the K Ingleside.

Central Subway

The second phase of the line was built as the Central Subway, which forms a crosstown link between South of Market and Chinatown via Union Square. Voters approved the Central Subway in 2003, and the alignment was selected in 2008. Construction began in 2012. After numerous delays, the Central Subway opened on November 19, 2022, with a weekend-only shuttle service operating between and . The T Third Street will be rerouted into the Central Subway for full service on January 7, 2023. Service will run every 10 minutes on weekdays and every 12 minutes on weekends. Shuttle trains signed "S Chase Center" will operate between Chinatown and for events at Chase Center.

Station listing

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. Stations south of Fourth and King feature short platforms that accommodate only two-car trains.

Future

These stations will be served by the T Third Street line when it moves into the Central Subway beginning in January 2023. At that time, the T will no longer serve stations between West Portal and 2nd and King, and will no longer be interlined with K Ingleside.

References

External links

SFMTA - K Ingleside/T Third Street

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{{Muni

Muni Metro lines
2007 establishments in California