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Location: Los Angeles, California
Owner: Los Angeles County Metropolitan Transportation Authority
Client: Eastside LRT Partners
00The Eastside Light Rail Transit Project is approximately six miles long, with eight new stations extending from Union Station in downtown Los Angeles east along 1st and 3rd Streets through various East Los Angeles communities. While most of the route is at-grade, a twin bore 1.8 mile-long tunnel is located under 1st Street with two cut-and-cover stations at Soto and Boyle Streets. The tunnel route intersects a commercial and residential district which requires building protection against settlement.
00Jacobs Associates provided geotechnical, structural, and tunnel engineering services in support of preliminary and final design. This work included TBM specification, building assessment, analysis of settlement due to tunneling, and design of building protection above the various underground transit structures. Building protection involved evaluation of building risk due to settlement during underground excavation. Buildings were divided into categories based on location nearest to tunnel drives, determined to be the highest risk, and those farther from tunnel drives as lower risk. During construction the buildings are monitored to determine the most appropriate solution to mitigate settlement. JA determined compensation grouting to be the most flexible building protection method based on geotechnical conditions. It will be utilized on an as-needed basis during the tunnel construction. This project is utilizing a combination of design-build and design-bid-build contract delivery methods. The project was bid at $670M.
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