Archive | Tunneling

26 March 2015 ~ 0 Comments

Featured Photos – March 25

A decorative set-back curb and wall located above the Central Subway tunnel entrance south of Harrison on 4th Street. View of the tunnel portal ramp from 4th and Stillman during construction of the portal walls, which will separate automobile traffic from light rail vehicles. Workers put up temporary bracing while they pour concrete for the […]

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12 February 2015 ~ 3 Comments

Tunnel Boring Machines’ Disassembly

Our recent time-lapse video highlights the break-through and removal of the tunnel boring machines (TBMs) at the retrieval shaft and gives a closer look at how work advanced at that site. The video shows TBM Mom Chung breaking into the water-filled retrieval shaft last June. The water is drained from the shaft for the arrival […]

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12 November 2014 ~ 1 Comment

Portal Structure Moves Forward

Under 4th Street, between Harrison and Bryant streets, work continues at the launch box site. This site is where tunnel boring machines, Mom Chung and Big Alma, were launched last year. The launch box is now being transformed into a portal (gateway structure). The portal will bring the light rail vehicles to the surface and vice-versa, […]

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28 August 2014 ~ 4 Comments

Dismantling Big Alma

After breaking through on June 11, the 750-ton tunnel boring machine (TBM) Big Alma was removed from the retrieval shaft in North Beach. TBM Mom Chung is currently in the process of being disassembled. To retrieve each TBM, the machines are cleared of debris, cut into sections, brackets re-wielded for attachment points, pieces hoisted out, […]

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25 July 2014 ~ 0 Comments

Project Advancements | July 26 – August 4, 2014

During the next 10 days, Central Subway work continues 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 click here or on the links below. You can also find construction, traffic detour, and Muni impact information on our […]

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20 June 2014 ~ 0 Comments

Construction Update | June 21 – June 30

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 […]

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13 June 2014 ~ 3 Comments

Construction Update | June 14 – June 23

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, click here or on the links below. We also post construction, traffic detour and Muni impact information on our […]

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06 June 2014 ~ 0 Comments

Construction Update | June 7 – June 16

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, click here on the links below. We also post construction, traffic detour and Muni impact information on our project Google […]

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30 May 2014 ~ 0 Comments

Construction Update | May 31 – June 9

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, click here or on the links below. We also post construction, traffic detour and Muni impact information on our […]

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16 May 2014 ~ 1 Comment

Construction Update | May 17 – May. 26

At 4th and Bryant I-80 off-ramp, three lanes may be closed on weeknights from 12 a.m. to 5 a.m. and one lane may be closed during the daytime from 10 a.m. to 3 p.m. In Union Square, one traffic lane will be closed from Geary to Powell from 8p.m. to 4a.m. starting Tuesday, May 20. […]

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