ATTN: IB 29 blocked on Gilman btwn Hawes and Bill Walsh Way due to heavy vehicle traffic. Expect 29 to reroute via Hawes to Gilman. No 29 svc btwn Hawes and Bill Walsh Way. (More: 8 in last 48 hours)

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Central Subway Newsletter for Summer/Fall 2013

Full Speed Ahead

A message from SFMTA Director of Transportation Edward D. Reiskin

This summer, tunneling commenced beneath 4th Street when Mom Chung, a 750-ton, 350-foot-long tunnel boring machine (TBM), started digging. Over the next year, the massive machine will travel deep beneath our city streets, extending the T Third Line underground beneath SoMa, Union Square, Chinatown and North Beach. Soon a twin TBM, named Big Alma, will launch to build a tunnel parallel to Mom Chung’s. The tunnels are integral to improving rapid transit in our city. When the Central Subway opens, T Third Line trains will travel between the 4th Street Caltrain station and Chinatown in just eight minutes, cutting travel times by more than half along this busy corridor.
 
As the TBMs tunnel, you can follow them on Twitter. They’re @MomChungtheTBM and @BigAlmatheTBM. Read more about them (and check out some great photos) in this issue's feature story.
 
In addition to this major construction milestone, we’ve awarded the Central Subway’s largest and final major construction contract to California-based firm Tutor Perini (more here). Under the contract, Tutor Perini will build the Central Subway’s subway stations, surface-level station, train tracks and operating systems. The contract includes strong provisions designed to encourage local hiring and provide opportunities for small businesses and disadvantaged San Franciscans. I’m pleased to say that the winning bid exceeded our robust Small Business Enterprise goals – Tutor Perini committed 25 percent of the contract amount to certified SBE firms.
 
Station construction will ramp up in Chinatown, Union Square and SoMa in the coming months. Look out for updates on our blog, social media and in weekly construction update emails. If you’re interested in staying informed about construction in your neighborhood, please sign up for our email updates or update your email preferences by visiting http://eepurl.com/oOs-b.
 
In North Beach, demolition of the Pagoda Palace is now complete. After the building stood vacant for two decades, contractor MH Construction began dismantling the former theater in July. Soon we will begin building a walled excavation, called a retrieval shaft, within the Pagoda Palace property lines. The retrieval shaft will allow us to remove Mom Chung and Big Alma from the ground after they arrive in North Beach next year.
 
We worked closely with the North Beach community and multiple city agencies to change the North Beach construction plan, significantly reducing impacts to local businesses and residents. I thank everyone involved for their hard work in improving our North Beach construction plan and achieving this important change Welders work behind the face of tunnel boring machine Mom Chung, creating a pink glow. The face of the machine is called a cutter head.

The Tunnel Boring Machines Have Arrived

In July, tunnel boring machine (TBM) Mom Chung started digging, beginning her journey north beneath 4th Street in SoMa to construct San Francisco’s first new subway tunnel in decades. Over the next 10 months, the 350-foot-long, 750-ton machine will excavate and construct the tunnel that southbound T Third Line trains will use when the Central Subway opens for revenue service.
 
An identical TBM, Big Alma, recently arrived in San Francisco. After about two months of assembly underground, she will begin constructing a tunnel parallel to Mom Chung’s.

The TBMs will travel beneath 4th Street, Stockton Street and Columbus Avenue, terminating in North Beach at the site of the old Pagoda Palace Theater. They will excavate and construct the 1.5-mile-long tunnels at a pace of approximately 40 feet per day, though their pace will vary based on ground conditions and other factors. Most of their journey will be through two major ground formations: the Franciscan complex, a bedrock formation that forms Nob Hill; and the Colma formation, a dense mixture of sand and clay.
 
The TBMs will be so far beneath the surface – between 40 and 120 feet underground – that no vibration or noise will be felt above ground when they pass below.

A crew of about 10 people operates the machine and bolts the tunnel segments together. Crews will be at work 24 hours a day, six days a week to build the Central Subway’s tunnels.
 
The tunnels are a key component in extending the T Third Line through SoMa, Union Square and Chinatown, vastly improving transit in these neighborhoods. By taking transportation underground on busy Stockton and 4th streets, travel times in peak periods will be cut by more than half.

The photos above and below this article show the installation and assembly of Mom Chung. The first segment of Mom Chung is lowered into the 4th Street underground work site. A close-up of one of Mom Chung's cutting teeth. A view inside the trailing gear, which makes up most of the length of Mom Chung. Welders help assemble the front portion of Mom Chung, called the shield.

Stations Contract Awarded to Tutor Perini

In May 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 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. The SFMTA Board of Directors voted unanimously to approve the award on June 4.
 

The Yerba Buena/Moscone Station (aerial view shown here) is one of th four stations included in the stations contract.
With 25 percent of the contract amount committed 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.

Tutor Perini is now mobilizing to begin the major construction associated with this contract. Construction will continue through 2018, with the Central Subway scheduled to open in 2019.