This portion of the Los Angeles County MTA light rail system extension into East Los Angeles, consisting of 7500 lf long twin subway tunnels, was constructed using two 21.5 ft Herrenknecht EPB tunnel machines. The tunnels were excavated in alluvial soils, with the alignment at an average depth of 60 ft, following directly below East 1st Street. Due to the known presence of both Methane and Hydrogen Suphide gas, the tunnels were classified as "Gassy" by CalOSHA. The liing consists of a one-pass, gasketed, precast concrete segmental lining, and a cast-in-place invert and walkway were included in the scope. Precast segmental liner was furnished by Traylor/Shea/Ghazi Precast. 

Construction Method: EPB
Start Date: Notice to Proceed 07/07/04
Completion Date: August 23, 2007
Scheduled completion: August 31, 2007
Owner: Metropolitan Transit Authority, Los Angeles, California
Joint Venture: Traylor/Frontier Kemper, JV - subcontractor to Eastside LRT Constructors (Washington/Obayashi/Schimick)

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