Central Subway Blog

About 80 feet below Ellis Street, we’re installing pipes into the ground around this shaft. We’ll use the pipes to inject grout into the ground, improving soil conditions near the existing Muni and BART tunnels.

During the next 10 days, construction to prepare for tunneling will continue in SoMa and Union Square. No Central Subway construction is planned in Chinatown or North Beach.

For descriptions of construction impacts in each neighborhood, click here or on the links below. We also post construction, traffic detour and Muni impact information on our project Google Map.

Construction impacts are planned to change at these locations by June 24:

• Northern SoMa (Market to Harrison):  Two lanes of traffic will remain closed on 4th Street between Howard and Folsom, but the traffic configuration will change (details in the Northern SoMa section). Construction will be underway on Saturdays until further notice. On 4th Street between Market and Stevenson, the sidewalk and two traffic lanes will remain closed on the eastern side of the street.

At these locations, current construction impacts are planned to continue until June 24:

• Southern SoMa (Harrison to King/Berry): Full closure of 4th Street between Harrison and Bryant will continue some evenings and weekends. Two lanes of traffic will remain open at all other times. Contact us at central.subway@sfmta.comif you have questions about the closure schedule. On Bryant Street at 5th Street, the left lane and several parking spaces will remain closed.
• Union Square: Stockton Street between Geary and Ellis will remain closed to vehicle traffic. Ellis Street between Stockton and Powell will remain closed to westbound traffic.
• Chinatown: No construction planned
• North Beach: No construction planned before June 24, but demolition of the Pagoda Palace is scheduled to begin in June. For more information, check out thisconstruction notice.

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

Crews continue to prepare tunnel boring machine Mom Chung for launch.

During the next 10 days, construction to prepare for tunneling will continue in SoMa and Union Square. No Central Subway construction is planned in Chinatown or North Beach.

For descriptions of construction impacts in each neighborhood, click here or on the links below. We also post construction, traffic detour and Muni impact information on our project Google Map.

Construction impacts are planned to change at these locations by June 17:

• Northern SoMa (Market to Harrison):  Two lanes of traffic will remain closed on 4th Street between Howard and Folsom, but the traffic configuration may change (details in the Northern SoMa section). Construction will be underway this Saturday, June 8, and next Saturday, June 15, on this block. On 4th Street between Market and Stevenson, the sidewalk and two traffic lanes will remain closed on the eastern side of the street.

At these locations, current construction impacts are planned to continue until June 17:

• Southern SoMa (Harrison to King/Berry): Full closure of 4th Street between Harrison and Bryant will continue some evenings and weekends. Two lanes of traffic will remain open at all other times. Contact us at central.subway@sfmta.com if you have questions about the closure schedule. On Bryant Street at 5th Street, the left lane and several parking spaces will remain closed.
• Union Square: Stockton Street between Geary and Ellis will remain closed to vehicle traffic. Ellis Street between Stockton and Powell will remain closed to westbound traffic.
• Chinatown: No construction planned
• North Beach: No construction planned before June 17, but demolition of the Pagoda Palace is scheduled to begin in June. For more information, check out this construction notice.

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

A tour group visits tunnel boring machine Mom Chung beneath busy 4th Street.

Tunnel boring machine Mom Chung is almost assembled and just about ready for launch. This month, the 350-foot-long, 750-ton tunnel-building behemoth will begin her journey north beneath the streets of San Francisco, constructing the city’s first new subway tunnel in decades.

Last week we celebrated Mom Chung’s upcoming journey with an event at the site where tunneling will begin. After speeches by Mayor Edwin M. Lee, Democratic Leader Nancy Pelosi’s Chief of Staff Robert Edmonson, Board of Supervisors President David Chiu, District 6 Supervisor Jane Kim and others, guests toured the underground site where Mom Chung is being assembled. They sent her off by signing their names on her cylindrical shield, wishing her a safe and successful voyage beneath SoMa, Union Square, Chinatown and North Beach.

The photos below are of the event, held last Thursday on and below 4th Street. For more photos, visit us on Flickr. To find out more about the event, check out this press release from the SFMTA.

Before the event, the stage was set with safety gear for special guests and honored speakers.

Reporters set up cameras, preparing for the arrival of Mayor Lee and other special guests.

A cheerful Mayor Lee talks about the many benefits of the Central Subway — reducing travel times, connecting San Francisco’s neighborhoods and preparing for the growth expected in the city in coming years and decades.

Supervisors Jane Kim and David Chiu listen to Mayor Lee’s speech. The Central Subway (and Mom Chung) will travel through their districts.

Mayor Lee prepares to cut the cake decorated with TBM Mom Chung. Thanks to Victoria Pastry for creating this delicious treat.

Central Subway Program Director John Funghi leads the first tour of the excavation, known as a launch box, where Mom Chung is being assembled and will begin tunneling.

At the entrance to the launch box, tour goers look with awe upon Mom Chung.

Mayor Lee signs Mom Chung. The TBM will help build “our future San Francisco.”

Others, including Supervisor Chiu, sign their names and messages on the TBM.

Gina Low Weiss, grandniece of Dr. Margaret “Mom” Chung, after whom the TBM is named, signs her name and writes her message on the machine.

This section of Mom Chung, known as the trailing gear, performs a variety of functions, including carrying excavated spoils out of the tunnel and bringing concrete tunnel segments in.

After the tour, participants exited the launch box, returning outside to a warm, sunny day.

Pedestrians cross the street near the Union Square construction site.

During the next 10 days, construction to prepare for tunneling will continue in SoMa and Union Square. No Central Subway construction is planned in Chinatown or North Beach.

For descriptions of construction impacts in each neighborhood, click here or on the links below. We also post construction, traffic detour and Muni impact information on our project Google Map.

Construction impacts are planned to change at these locations by June 3:

• Northern SoMa (Market to Harrison): On 4th Street between Market and Stevenson, the sidewalk and two traffic lanes will remain closed on the eastern side of the street except from 8 p.m. Thursday, May 30, to 6 a.m. Friday, May 31. At that time, three lanes will be closed. Two lanes of traffic will remain closed on 4th Street between Howard and Folsom, but the traffic configuration may change (details in the Northern SoMa section). Construction will be underway this Saturday, May 25, and Sunday, May 26, on this block.
• Union Square: Construction will be underway this Sunday, May 26, from 6 a.m. to 4 p.m. Stockton Street between Geary and Ellis will remain closed to vehicle traffic. Ellis Street between Stockton and Powell will remain closed to westbound traffic.

At these locations, current construction impacts are planned to continue until June 3:

• Southern SoMa (Harrison to King/Berry): Full closure of 4th Street between Harrison and Bryant will continue on some evenings and weekends. Two lanes of traffic will remain open at all other times. Please contact us at central.subway@sfmta.com if you have questions about the closure schedule. On Bryant Street at 5th Street, the left lane and several parking spaces will remain closed.
• Chinatown: No construction planned
• North Beach: No construction planned before June 3, but demolition of the Pagoda Palace is scheduled to begin in June. For more information, check out this construction notice.

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

Construction of the Union Square/Market Street Station, shown here, is included in the major contract awarded earlier this week.

This week the SFMTA awarded the contract to construct the Central Subway’s stations, train tracks and operating systems to California-based firm Tutor Perini. Tutor Perini’s bid of $840 million was the lowest of three bids received for the contract, SFMTA Contract No. 1300, the largest and final major construction contract for the Central Subway Project.

After review, Agency staff determined that the bid meets contract solicitation requirements and recommended approval. At their meeting Tuesday, the SFMTA Board of Directors voted unanimously to approve the award.

With 25 percent of the contract amount going to certified Small Business Enterprise (SBE) firms, Tutor Perini significantly exceeded the SBE participation goal of 20 percent. In addition, Tutor Perini will set aside at least 50 percent of the contract’s trucking and hauling work for certified SBE firms, invest at least $1.5 million in hiring socially and economically disadvantaged individuals for entry-level jobs, and provide socially and economically disadvantaged individuals with at least 40,000 hours of on-the-job training for construction management positions.

Under Contract 1300, Tutor Perini will construct the following elements of the Central Subway:

• The Chinatown Station, a subway station with an entrance at Stockton and Washington streets;
• The Union Square/Market Street Station, a subway station with entrances at Stockton and Geary streets and Stockton and Ellis streets;
• A concourse connecting the Union Square/Market Street Station to the existing Powell Street Muni/BART Station;
• The Yerba Buena/Moscone Station, a subway station with an entrance at 4th and Clementina streets;
• The 4th and Brannan Station, a surface-level station on 4th Street between Brannan and Bryant streets;
• Surface tracks on 4th Street between 4th and King streets and the subway tunnel portal on 4th Street between Bryant and Harrison streets;
• Trackbed, tracks, switches and train control systems within the Central Subway tunnel.

In the coming weeks and months, Tutor Perini and the SFMTA will mobilize to begin the major construction associated with the contract. Construction will continue through 2018, with the Central Subway scheduled to open in 2019.

A worker prepares a concrete cylinder for installation underground. The cylinder is one component of a wall that will eventually be integrated into the Union Square/Market Street Station.

During the next 10 days, construction to prepare for tunneling will continue in SoMa and Union Square. No Central Subway construction is planned in Chinatown or North Beach; however, demolition of the Pagoda Palace in North Beach is slated to begin in mid-June.

For descriptions of construction impacts in each neighborhood, click here or on the links below. We also post construction information on our project Google Map.

Construction impacts are planned to change at these locations by May 27:

• Northern SoMa (Market to Harrison): On 4th Street between Howard and Folsom, two lanes of traffic will remain open, but the traffic configuration will change starting Thursday, May 23 (details at the Northern SoMa link). On 4th Street between Market and Stevenson, the sidewalk and two traffic lanes will remain closed on the eastern side of the street.
• North Beach: No construction planned before May 27, but demolition of the Pagoda Palace is scheduled to begin in mid-June. For more information, check out this construction notice.

At these locations, current construction impacts are planned to continue until May 27:

• Southern SoMa (Harrison to King/Berry): Full closure of 4th Street between Harrison and Bryant will continue on some evenings and weekends. Two lanes of traffic will remain open at all other times. Please contact us at central.subway@sfmta.com if you have questions about the closure schedule. On Bryant Street at 5th Street, the left lane and several parking spaces will remain closed.
• Union Square: Stockton Street between Geary and Ellis will remain closed to vehicle traffic. Ellis Street between Stockton and Powell will remain closed to westbound traffic.
• Chinatown: No construction planned

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

This time lapse video — our first ever — shows the first steps of installing and assembling tunnel boring machine Mom Chung.

For the past few weeks, Central Subway crews have worked day and night to install and assemble our first tunnel boring machine, Mom Chung, underground beneath 4th Street.

We’ve documented the process on three time lapse cameras installed at this major construction site. The cameras took photos every two minutes, and we compiled and edited the images to create the video above.

In it, you’ll see our crews construct a specialized crane, called a gantry crane, over 4th Street to prepare for Mom Chung’s arrival. Then hundreds of tons of massive Mom Chung are lowered underground and assembled by Central Subway workers. The segments seen here make up Mom Chung’s shield (the part that builds the tunnel) and cutter head (the part that excavates). At the end of the video, we install an auger screw, which is used to transport dirt and spoils through the front of the TBM and onto a series of conveyors.

Taken from April 22 to May 3, the video contains 1,917 images. Check it out here or on our YouTube channel. (And be sure to check out our construction videos, too.)

We’ll post more time lapse videos soon, including one of the entire TBM assembly process, as we continue to document construction of this essential improvement to San Francisco’s public transportation system.

Crews continue to install subsurface pipes on 4th Street between Market and Stevenson. When the tunnel boring machines pass below, we will use to inject grout into the ground and improve soil conditions here.

During the next 10 days, construction to prepare for tunneling will continue in SoMa and Union Square. No Central Subway construction is planned in Chinatown or North Beach.

For descriptions of construction impacts in each neighborhood, click here or on the links below. We also post construction, traffic detour and Muni impact information on our project Google Map.

Construction impacts are planned to change at these locations by May 20:

• Southern SoMa (Harrison to King/Berry): The on-ramp to westbound I-80 will remain open next week. Full closure of 4th Street between Harrison and Bryant will continue on some evenings and weekends. Two lanes of traffic will remain open on this block on at all other times. Please contact us at central.subway@sfmta.com if you have questions about the closure schedule. On Bryant Street at 5th Street, the left lane and several parking spaces will remain closed.

At these locations, current construction impacts are planned to continue until May 20:

• Northern SoMa (Market to Harrison): On 4th Street between Market and Stevenson, the sidewalk and two traffic lanes will remain closed on the eastern side of the street. Two lanes of traffic will remain closed on 4th Street between Howard and Folsom.
• Union Square: Stockton Street between Geary and Ellis will remain closed to vehicle traffic. Ellis Street between Stockton and Powell will remain closed to westbound traffic.
• Chinatown: No construction planned
• North Beach: No construction planned

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

San Francisco Mayor Edwin M. Lee takes a look at tunnel boring machine Mom Chung in the excavation under 4th Street where tunneling will begin.

Yesterday, Mayor Edwin M. Lee paid a visit to the construction site where tunneling will begin and saw Mom Chung, the 350-foot-long tunnel boring machine currently being assembled underground.

Speaking to reporters in front of the digging cutter head of Mom Chung, Mayor Lee said he was excited about the Central Subway, calling the T Third Line extension “one of the most important projects for the future of San Francisco.”

SFMTA Board Chairman Tom Nolan, SFMTA Director of Transportation Edward D. Reiskin, Central Subway Program Director John Funghi, key city officials and members of Central Subway team accompanied Mayor Lee under 4th Street to show him the major excavation where tunneling will begin. Check out the photos below for more on the Mayor’s visit to this important construction site.

The tour group heads down the ramp near 4th and Bryant and into the excavation beneath the roadway.

The tour group makes its way through the excavation and toward Mom Chung. From left to right: Director Reiskin, Mayor Lee, John Funghi, tunnel contract Resident Engineer Sarah Wilson.

Sarah Wilson, the engineer overseeing construction of the Central Subway tunnels, explains the details of the tunneling process to Mayor Lee. From left to right: SFPUC Assistant General Manager Emilio Cruz, SFPUC General Manager Harlan Kelly, Jr., Mayor Lee, the Mayor’s Chief of Staff Steve Kawa, John Funghi, Sarah Wilson.

Mayor Lee responds to questions from reporters. From left to right: Director Reiskin, Chairman Nolan, Mayor Lee, John Funghi, SFMTA Board Vice Chairman Cheryl Brinkman, Sarah Wilson.

The tour group gathers around the front of Mom Chung. Called the cutter head, this spinning excavator will dig through the earth under 4th Street, Stockton Street and Columbus Avenue.

Representatives of tunnel construction contractor Barnard Impregilo Healy meet Mayor Lee and Director Reiskin. From left to right: Assistant Project Superintendent Andy Granger, Mayor Lee, Project Manager Ben Campbell, Director Reiskin.

Read more about the Mayor’s visit in today’s San Francisco Chronicle. Tunneling is slated to begin in June.

Crews are excavating a shaft on Ellis Street near where the Central Subway tunnels will pass beneath the existing BART and Muni tunnels. Crews will perform ground improvements here.

During the next 10 days, construction to prepare for tunneling will continue in SoMa and Union Square. No Central Subway construction is planned to occur in Chinatown or North Beach.

Descriptions of construction impacts in each neighborhood are available here or at the links below. We also post construction, traffic detour and Muni impact information on our project Google Map.

Construction impacts are planned to change at these locations by May 13:

• Construction impacts continuing at all sites.

At these locations, current construction impacts are planned to continue until May 13:

• Southern SoMa (Harrison to King/Berry): Full closure of 4th Street between Harrison and Bryant will be in effect some evenings and weekends while we lower parts of the tunnel boring machine into the excavation beneath the roadway. Two lanes of traffic will remain open on this block on at all other times. Please contact us at central.subway@sfmta.com if you have questions about the closure schedule. On Bryant Street at 5th Street, the left lane and several parking spaces will be closed for use as a staging area for tunnel boring machine installation.
• Northern SoMa (Market to Harrison): On 4th Street between Market and Stevenson, the sidewalk and two traffic lanes will remain closed on the eastern side of the street. Two lanes of traffic will remain closed on 4th Street between Howard and Folsom.
• Union Square: Stockton Street between Geary and Ellis will remain closed to vehicle traffic. Ellis Street between Stockton and Powell will remain closed to westbound traffic.
• Chinatown: No construction planned
• North Beach: No construction planned

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