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SFMTA’s Central Subway will connect San Francisco’s southeast neighborhoods to downtown and Chinatown. Whether you’re a concerned citizen, business owner, Muni customer, or just stumbled onto our blog, we welcome your questions and encourage you to connect with us. Follow us for the latest Central Subway news and information.

31 January 2014 ~ 0 Comments

Construction Update | Feb. 1-10

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TBM Big Alma is crossing under Market Street and BART this week. This photo shows the back of the TBM as it approaches this key juncture.

During the next 10 days, Central Subway work will continue at sites in SoMa, Union Square, Chinatown and North Beach. This post contains brief updates about what is happening in each neighborhood. For more detailed information, click here or on the links below. We also post construction, traffic detour and Muni impact information on our project Google Map.

Southern SoMa (Harrison to King/Berry): This week we began potholing for utilities on the east side of 4th Street between Bryant and Bluxome. Work will continue in this area next week. At the tunnel launch box on 4th Street between Harrison and Bryant, tunneling continues with both TBMs.

Northern SoMa (Market to Harrison): Construction will continue on 4th between Market and Stevenson as the second TBM passes through the area. On 4th Street between Folsom and Harrison, the road expected to reopen in February. At 4th and Folsom, work to prepare for the Yerba Buena/Moscone Station continues. Work may include demolishing the roadway within the construction zone to prepare to construct underground station walls. This work will be noisy.

Union Square: Stockton Street between Ellis and Geary is closed to vehicular traffic to allow for construction of the Union Square/Market Street Station. On Ellis Street, crews may work through the weekend as the second TBM crosses under Market Street. On Stockton Street, crews will work on Saturday mobilizing equipment to the construction zone.

Chinatown: Work to prepare for the Chinatown Station continues within the future station site and on the adjacent section of Washington Street.

North Beach: Next week work will continue at Columbus & Union, 1455 Stockton and 1731-1741 Powell. At 1731-1741 Powell, construction may be in progress on Saturdays from 7 a.m. to 5 p.m.

We appreciate your patience and support while we build this essential upgrade to San Francisco’s public transportation system.

28 January 2014 ~ 0 Comments

Second Central Subway TBM to pass under Market Street, BART this week

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Tunnel boring machine Big Alma, shown here, will cross under BART and Market Street this week.

This week the Central Subway’s second tunnel boring machine (TBM) will pass beneath Market Street and the existing Bay Area Rapid Transit (BART) and Muni Metro tunnels, crossing from SoMa and into Union Square. The tunnel, one of two being constructed as part of the Central Subway Project, will allow T Third Line trains to travel quickly beneath 4th Street and Stockton Street, cutting transit travel times by more than half along this busy corridor.

The SFMTA has worked in close coordination with BART and an independent panel of top tunneling experts to plan and carry out this key phase of tunnel construction. To pass beneath Market Street and the existing transit tunnels, TBM Big Alma will turn slightly left beneath 4th Street just south of Market Street. The machine will then veer right to head north under Market Street and then Stockton Street.  The new T Third Line tunnels will be about 10 feet below the existing BART tunnels.

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This graphic shows the path the Central Subway TBMs will take when they pass under Market Street. The second TBM, Big Alma, is making this crossing this week.

Starting today, Big Alma will be in operation 24 hours a day to build the approximately 425 feet of new tunnel beneath the Market Street tunnels. Late last year the first TBM, called Mom Chung, safely and successfully completed the same undercrossing, using the same techniques and interagency coordination. Mom Chung is now beginning to tunnel under Nob Hill, heading toward Chinatown. Including both tunnels, tunneling contractor Barnard Impregilo Healy (BIH) has constructed more than 6,900 feet of tunnel under 4th Street and Stockton Street so far.

In preparation for the crossing, the contractor has injected a ground-stabilizing grout underground near the BART tunnels, accessing this subterranean area via a deep shaft they constructed on Ellis Street. About 150 monitoring devices installed in the Powell Street Station and on neighboring buildings will provide live data feeds about tunneling conditions to web applications that the SFMTA, the contractor, BART and an independent panel of tunneling experts can view at all times. Similar devices are installed along the entire tunneling path, from 4th and Bryant in SoMa to Columbus and Powell in North Beach. The readings of these instruments and others on the TBMs themselves allow the tunneling contractor to respond rapidly to ground conditions around the machines as they move forward.

The crossing under BART may last up to six days. Tunneling may cause BART to run at slower speeds in the area.

More information is available in this press release from the SFMTA.

24 January 2014 ~ 0 Comments

Construction Update | Jan. 25-Feb. 3

Newly-installed pedestrian walkway barriers on Stockton, at Ellis.On Stockton Street, the contractor has installed these barricades to protect pedestrians while construction of the Union Square/Market Street Station proceeds in the roadway.

During the next 10 days, Central Subway work will continue at sites in SoMa, Union Square, Chinatown and North Beach. This post contains brief updates about what is happening in each neighborhood. For more detailed information, click here or on the links below. We also post construction, traffic detour and Muni impact information on our project Google Map.

Southern SoMa (Harrison to King/Berry): We plan to begin potholing for utilities on 4th Street between Bryant and King next week, on Monday, Jan. 27. Potholing will commence on the east side of 4th Street between Bryant and Bluxome, proceeding at other locations along the block over the coming months. More details are in the Southern SoMa section. At the tunnel launch box on 4th Street between Harrison and Bryant, tunneling continues with both TBMs.

Northern SoMa (Market to Harrison): Construction will continue on 4th between Market and Stevenson next week and this weekend (Jan. 25-26) as the second TBM passes through the area. On 4th Street between Folsom and Harrison, the road expected to reopen in February. At 4th and Folsom, work to prepare for the Yerba Buena/Moscone Station continues. Work may include demolishing the roadway within the construction zone to prepare to construct underground station walls. This work will be noisy.

Union Square: Stockton Street between Ellis and Geary is closed to vehicular traffic to allow for construction of the Union Square/Market Street Station. On Ellis Street, crews may work through the weekend to prepare for the crossing of the second TBM under Market Street. On Stockton Street, crews will work on Saturday installing barricades around the construction zone.

Chinatown: Work to prepare for the Chinatown Station continues within the future station site and on the adjacent section of Washington Street.

North Beach: Work on Columbus Avenue at Union Street will continue next week, Monday to Friday. Work will continue at 1455 Stockton and 1731-1741 Powell, within the property lines. At 1731-1741 Powell, construction may be in progress on Saturdays from 7 a.m. to 5 p.m.

We appreciate your patience and support while we build this essential upgrade to San Francisco’s public transportation system.

17 January 2014 ~ 0 Comments

Construction Update | Jan. 18-27

140114_1104_NB_TunnelTunneling is proceeding beneath 4th Street with TBM Big Alma. This TBM is expected to pass beneath Market Street around the end of January.

During the next 10 days, Central Subway work will continue at sites in SoMa, Union Square, Chinatown and North Beach. This post contains brief updates about what is happening in each neighborhood. For more detailed information, click here or on the links below. We also post construction, traffic detour and Muni impact information on our project Google Map.

Southern SoMa (Harrison to King/Berry): We plan to begin potholing for utilities on 4th Street between Bryant and King the week of Jan. 20. Potholing will commence on the east side of 4th Street between Bryant and Bluxome, proceeding at other locations along the block over the coming months. More details are in the Southern SoMa section. At the tunnel launch box on 4th Street between Harrison and Bryant, tunneling continues with both TBMs.

Northern SoMa (Market to Harrison): Construction is planned to resume on 4th between Market and Stevenson late next week, when the second TBM passes through the area. We plan to begin restoring 4th Street between Folsom and Harrison during the next two weeks, with the road expected to reopen in February. At 4th and Folsom, work to prepare for the Yerba Buena/Moscone Station continues. Work may include demolishing the roadway within the construction zone to prepare to construct underground station walls.

Union Square: Stockton Street between Ellis and Geary is closed to vehicular traffic to allow for construction of the Union Square/Market Street Station. Stockton between Ellis and O’Farrell will close next week as crews continue to install decorative barricades around the construction zone.

Chinatown: Work to prepare for the Chinatown Station continues within the future station site and on the adjacent section of Washington Street. Construction will be in progress this Saturday, January 18, within the station construction zone.

North Beach: Work on Columbus Avenue at Union Street is planned to start next week, continuing for approximately one month. More details in the North Beach section. Work will continue at 1455 Stockton and 1731-1741 Powell, within the property lines.

We appreciate your patience and support while we build this essential upgrade to San Francisco’s public transportation system.

10 January 2014 ~ 0 Comments

Construction Update | Jan. 11-20

140108_1008_UMSThis week, we closed a block of Stockton Street to prepare to build the Union Square/Market Street Station. Crews are installing decorative barricades around the construction zone.

During the next 10 days, Central Subway work will continue at sites in SoMa, Union Square, Chinatown and North Beach. This post contains brief updates about what is happening in each neighborhood. For more detailed information, click here or on the links below. We also post construction, traffic detour and Muni impact information on our project Google Map.

Southern SoMa (Harrison to King/Berry): We expect to begin potholing for utilities on 4th Street between Bryant and King the week of Jan. 20. At the tunnel launch box on 4th Street between Harrison and Bryant, tunneling continues with both TBMs.

Northern SoMa (Market to Harrison): We plan to begin restoring 4th Street between Folsom and Harrison during the next two weeks. Until then, the traffic pattern may change to allow for underground sewer surveys. At 4th and Folsom, work to prepare for the Yerba Buena/Moscone Station continues. Work may include demolishing the roadway within the construction zone to prepare to construct underground station walls.

Union Square: Stockton Street between O’Farrell and Geary is closed to vehicular traffic to allow for construction of the Union Square/Market Street Station. Stockton between Ellis and O’Farrell may close next week as crews continue to install decorative barricades around the construction zone.

Chinatown: Work to prepare for the Chinatown Station continues within the future station site and on the adjacent section of Washington Street. On Jackson Street adjacent to Stockton Street, the contractor may be performing underground borings during the day.

North Beach: Near the intersection of Columbus Avenue and Stockton Street, crews will be performing underground sewer work for approximately one month, starting next week. This work does not involve excavation. The southbound bus stop on Stockton Street at Columbus will be relocated to Stockton and Vallejo during work hours (Monday to Friday, 9 a.m. to 3 p.m.). See the North Beach section for more details. Work on Columbus Avenue at Union Street is currently on hold. We will provide additional details about this work before it recommences. Work will continue at 1455 Stockton and 1731-1741 Powell, within the property lines.

We appreciate your patience and support while we build this essential upgrade to San Francisco’s public transportation system.

03 January 2014 ~ 1 Comment

Construction Update | January 4-13, 2014

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At 1731-1741 Powell, we are constructing a retrieval shaft to remove two tunnel boring machines from the ground when tunneling is finished.

Next week traffic modifications on Stockton between Geary and Ellis streets near Union Square will recommence to accommodate construction of the Central Subway Union Square/Market Street station.

During the next 10 days, Central Subway work will continue at sites in SoMa, Union Square, Chinatown and North Beach. This section contains brief updates about what is happening in each neighborhood. For more detailed information, scroll down or click on the links below. We also post construction, traffic detour and Muni impact information on our project Google Map.

Southern SoMa (Harrison to King/Berry): We expect to begin potholing for utilities on 4th Street between Bryant and King in mid-January. At the tunnel launch box on 4th Street between Harrison and Bryant, tunneling continues with both TBMs.

Northern SoMa (Market to Harrison): We plan to begin restoring 4th Street between Folsom and Harrison during the next two weeks. Until then, the traffic pattern may change to allow for underground sewer surveys. At 4th and Folsom, work to prepare for the Yerba Buena/Moscone Station continues. Work may include demolishing the roadway within the construction zone to prepare to construct underground station walls.

Union Square: Next week, Stockton Street between Ellis and Geary will be closed to vehicular traffic to allow for construction of the Union Square/Market Street Station. The construction zone on Ellis Street will remain in place.

Chinatown: Work to prepare for the Chinatown Station continues within the future station site and on the adjacent section of Washington Street. On Jackson Street adjacent to Stockton Street, the contractor may be performing underground borings some nights next week.

North Beach: Work on Columbus Avenue at Union Street may resume next week. Work will continue at 1455 Stockton and 1731-1741 Powell, within the property lines.

We appreciate your patience and support while we build this essential upgrade to San Francisco’s public transportation system.

-The Central Subway Team

 

20 December 2013 ~ 0 Comments

Construction Update | Dec. 21-Jan. 6

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In a parking lot at Stockton and Green, crews have built this underground shaft. From it, we will improve and stabilize ground conditions beneath Columbus Avenue during tunneling.


Due to the upcoming holidays, this update covers the next two weeks of Central Subway work. There will be no update next Friday, Dec. 27. Happy holidays from the Central Subway team!


During the next 17 days, Central Subway work will continue at sites in SoMa, Union Square, Chinatown and North Beach. This post contains brief updates about what is happening in each neighborhood. For more detailed information, click here or on the links below. We also post construction, traffic detour and Muni impact information on our project Google Map.

In honor of Christmas and New Year’s Day, no construction will take place on Dec. 25 or Jan. 1. Starting in the new year, work will recommence on Columbus Avenue in North Beach and on Stockton Street in Union Square.

Southern SoMa (Harrison to King/Berry): We now expect to begin potholing for utilities on 4th Street between Bryant and King in January. At the tunnel launch box on 4th Street between Harrison and Bryant, tunneling continues with both TBMs.

Northern SoMa (Market to Harrison): We plan to begin restoring 4th Street between Folsom and Harrison during the next two weeks. Until then, the traffic pattern may change to allow for underground sewer surveys. At 4th and Folsom, work to prepare for the Yerba Buena/Moscone Station continues. Work may include demolishing the roadway within the construction zone to prepare to construct underground station walls.

Union Square: Construction is now paused on Stockton Street, resuming in January. Stockton Street between Ellis and Geary is tentatively planned to close to vehicle traffic on Thursday, Jan. 2, to allow for construction of the Union Square/Market Street Station. The construction zone on Ellis Street will remain in place.

Chinatown: Work to prepare for the Chinatown Station continues within the future station site and on the adjacent section of Washington Street.

North Beach: On Columbus Avenue at Union Street, construction is planned to resume Thursday, Jan. 2. Work will continue at 1455 Stockton and 1731-1741 Powell, within the property lines. No construction is planned at 1731-1741 Powell from Christmas to New Year’s Day.

We appreciate your patience and support while we build this essential upgrade to San Francisco’s public transportation system.

13 December 2013 ~ 0 Comments

Construction Update | Dec. 14-23

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Underground on 4th Street, two tunnels are now in construction. Here we see the entrances to both, beneath 4th and Harrison.

During the next 10 days, Central Subway work will continue at sites in SoMa, Union Square, Chinatown and North Beach. This post contains brief updates about what is happening in each neighborhood. For more detailed information, click here or on the links below. We also post construction, traffic detour and Muni impact information on our project Google Map.

Southern SoMa (Harrison to King/Berry): We now expect to begin potholing for utilities on 4th Street between Bryant and King in January. At the tunnel launch box on 4th Street between Harrison and Bryant, tunneling continues with both TBMs.

Northern SoMa (Market to Harrison): Next week the contractor will begin restoring the work zone on 4th Street between Folsom and Harrison. The traffic pattern may change to allow for underground sewer surveys, with construction in progress in the intersection of 4th and Harrison and, tentatively, 4th and Folsom. At 4th and Folsom, work to prepare for the Yerba Buena/Moscone Station continues. Work includes demolishing the roadway within the construction zone to prepare to construct underground station walls. This work will be noisy.

Union Square: Construction is now paused on Stockton Street, resuming in January. Work will continue on Ellis Street during December to allow for ground improvements related to tunneling.

Chinatown: Work to prepare for the Chinatown Station continues within the future station site and on the adjacent section of Washington Street. On Clay and Jackson streets adjacent to Stockton Street, the contractor may be performing underground borings some nights next week.

North Beach: Construction is now paused on Columbus Avenue, resuming in January. Work will continue on private property at 1455 Stockton and 1731-1741 Powell to ensure we are ready for the arrival of the first TBM in the spring.

We appreciate your patience and support while we build this essential upgrade to San Francisco’s public transportation system.

06 December 2013 ~ 0 Comments

Construction Update | December 7-16

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Inside TBM Mom Chung, the new tunnel curves as it passes below Market Street. Our tunneling crews successfully and safely completed the crossing under BART last week.

We completed an important construction milestone last week as our tunneling contractor and TBM Mom Chung successfully and safely tunneled under Market Street and the existing BART and Muni tunnels. The TBM is now under Stockton Street in Union Square.

During the next 10 days, Central Subway work will continue at sites in SoMa, Union Square, Chinatown and North Beach. This post contains brief updates about what is happening in each neighborhood. For more detailed information, click here or on the links below. We also post construction, traffic detour and Muni impact information on our project Google Map.

Southern SoMa (Harrison to King/Berry): We expect to begin potholing for utilities on 4th Street between Bryant and King the week of Dec. 16. At the tunnel launch box on 4th Street between Harrison and Bryant, tunneling continues with both TBMs.

Northern SoMa (Market to Harrison): We have reestablished our work zone on 4th Street between Folsom and Harrison, in front of Pacific Bicycle. Work here involves improving ground conditions as the second TBM, Big Alma, passes underground. Work is currently paused at 4th and Stevenson, to resume when Big Alma reaches that area. At 4th and Folsom, we are building a covered walkway adjacent to the construction site on 4th Street and Clementina.

Union Square: Construction is now paused on Stockton Street, resuming in January. Work will continue on Ellis Street during December to allow for ground improvements related to tunneling.

Chinatown: Last week our crews closed a portion of Washington Street just west of Stockton Street to allow for utility work and the construction of underground Chinatown Station walls. Tentative: On Clay and Jackson streets adjacent to Stockton Street, the contractor may be performing underground borings some nights next week.

North Beach: Construction is now paused on Columbus Avenue, resuming in January. Work will continue on private property at 1455 Stockton and 1731-1741 Powell to ensure we are ready for the arrival of the first TBM in the spring. One morning next week, heavy equipment will be delivered to the construction site at the 1455 Stockton parking lot early in the morning, before regular working hours.

We appreciate your patience and support while we build this essential upgrade to San Francisco’s public transportation system.

04 December 2013 ~ 6 Comments

Time-lapse video: The first months of tunneling with TBM Mom Chung

Using time-lapse cameras installed underground, we’ve condensed the first months of tunneling into this captivating two-minute video. In the video, Central Subway crews assemble tunnel boring machine (TBM) Mom Chung and drive the state-of-the-art tunnel builder north under 4th Street to build San Francisco’s first new subway line in decades. The video shows the TBM assembly process, installation of the first tunnel rings, removal of excavated ground spoils and other aspects of the complex tunneling operation.

By the end of the video, Mom Chung has tunneled from her launch box south of 4th and Harrison to 4th between Folsom and Howard. Since we captured this footage, she has mined much farther north, crossing successfully and safely under Market Street and the existing BART and Muni tunnels last weekend.

We thank our tunneling crews and tunneling contractor Barnard Impregilo Healy for their hard work to build the Central Subway, extending the Muni Metro T Third Line through SoMa, Union Square and Chinatown. Stay tuned for more time-lapse videos as construction proceeds.