17 August 2012 ~ 0 Comments

Construction Update: Tunnel preparation underway at four sites, Union Square utility relocation substantially complete

Tunnel pre-construction work is now underway on Ellis Street. The tall machine shown here on the right is used to perform ground stabilization work known as jet grouting.

Tunnel pre-construction has continued to ramp up in recent weeks as tunneling contractor Barnard Impregilo Healy mobilized at two new sites along the project alignment:

  • Around Union Square, work is underway on Stockton Street to prepare to construct below-ground walls, called headwalls, which will become permanent components of the future Union Square/Market Street Station. On Ellis Street, the contractor is performing ground stabilization work known as jet grouting. To facilitate construction, traffic modifications have gone into effect on Stockton Street, Ellis Street and Grant Avenue.
  • In North Beach, the contractor began relocating utility lines along Columbus Avenue between Union and Powell streets. This work will be underway for approximately four months, with additional construction on track to begin next year.

Also in Union Square, contractor Synergy Project Management has finished most major utility relocation work at the future site of the Union Square/Market Street Station. Sidewalks and streets in the area have been restored, and only cleanup, detail work and below-ground AT&T and PG&E work remain before this contract is completed.

The sidewalks and stores on Stockton Street are open to pedestrians and shoppers during Central Subway construction.

Here’s what to expect in the next three weeks as tunnel pre-construction continues in SoMa, Union Square and North Beach:

  • Tunnel Launch Box (4th Street between Bryant and Harrison streets): The contractor will continue constructing below-ground walls around the perimeter of this major excavation site. Current work hours here are 5 a.m. to 1 a.m., Monday through Friday, and 6 a.m. to 2:30 p.m. on Saturday. At least two lanes of traffic on 4th Street will remain open at all times.
  • Yerba Buena/Moscone Station Headwalls (4th Street between Folsom and Howard streets):  The tunneling contractor will install below-ground walls, called headwalls, at the site of the future Yerba Buena/Moscone Station. The walls will cross 4th Street at two points on this block. Current work hours at this site are 7 a.m. to 4 p.m., Monday through Friday. At least two lanes of traffic on 4th Street will remain open at all times.
  • Union Square Tunneling Pre-Construction (Stockton Street between Ellis and Geary streets and Ellis Street between Stockton and Powell streets): The contractor is performing utility demolition, potholing and ground stabilization work called jet grouting. Installation of below-ground walls, called headwalls, will follow. Current construction hours at this site are Monday to Friday, 7 a.m. to 5 p.m. For more information about the traffic modifications now in effect in the Union Square area, check out this recent blog post.
  • North Beach Utility Relocation (Columbus Avenue between Union and Powell streets): The contractor will continue with utility relocation. Construction hours are Monday through Friday, 7 a.m. to 3:30 p.m. One lane of traffic will be closed at a time on one block of Union Street, Powell Street or Columbus Avenue during construction hours. For more information on construction in North Beach, check out this recent blog post.

A complete, current three-week construction schedule, including detailed, site-specific transit and traffic impacts, is available online for the tunnel contract. We also post construction, auto detour and Muni impact information on our project Google Map.

We appreciate your continued patience while construction is in progress.

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