Tunnel Business Magazine

OCT 2018

TBM: Tunnel Business Magazine is the market leader for North America. TBM is written for leading professionals in all aspects of tunneling and covers project stories, design elements, contracting strategies, legal issues, new technology and more.

Issue link: http://digital.tunnelingonline.com/i/1042145

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Page 37 of 47

3 8 TUNNELINGONLINE.COM TBM: TUNNEL BUSINESS MAGAZINE // OCTOBER 2018 CALIFORNIA Los Angeles Regional Connector Transit Project Regional Connector Constructors (Skanska-Traylor JV) The Regional Connector Project is in the heart of downtown Los Angeles in a congested urban environment that provides numerous challenges and requires coordination with multiple third parties. The Regional Connector Project will connect three operating rails sy o Blue and Expo Lines on the West and the Gold Line on the East. When complete, transit riders will no longer need multiple transfers and can travel north-south and east-west on the same system. The tunneling portion of the $1.75 billion Regional Connector Transit Project for the L opolitan Transportation Authority involves 5,795 ft of twin tunnels with an excavated TP was issued July 7, 2014 with a forecast completion date of December 2021. The ground conditions range from alluvium soils to clayey siltstone of the Fernando formation, with the potential for methane, hydrogen sulfide gas, and boulders. The groundwater table is generally above the tunnel alignment. Pressure balance tunneling utilizing an EPB required, along with precast concrete segments with double gaskets as the tunnel lining system. The tunnel depth (cover) ranges from 25 ft to approximately 120 ft and crosses b o Red Line heavy rail tunnels with less than 7 ft of clearance. The Regional Connector includes approximately 2,100 ft of cut-and- cover and retained-cut guideway, a 300 ft crossover cavern excavated by Sequential Excavation d chniques, and three cut-and-cover subway stations. The bored tunnels were excavated by concurrently with the construction of the three stations, requiring coordination between the cut-and-cover operations and cavation. As of September 2018, construction progress includes; • The bored tunnels were completed been demobilized. The three cross passages have been excavated and the concrete lining installed. Invert concrete and walkways are underway. • The Little Tokyo/Arts District Station excavation and bracing as well as invert concrete are ongoing. • The excavation and bracing for the 90-ft deep Historic Broadway Station is complete and HDPE gas/ water proofing as well as invert concrete are underway. • The mining and initial shotcrete liner f vern started on y 30, 2018. The cavern is being constructed utilizing three staggered drifts. The final dimensions will be 300' long x 58' wide x 36' high. The cavern is on the east side of the of the Broadway Station and will be used as a cross- over to facilita o operations. • The excavation and bracing for the Grand Av Arts/Bunker Hill Station is complete and HDPE gas/water proofing as well as invert and wall concrete is underway. • The Flower Street cut and cover tunnel progress continues. Street decking is complete while T U N N E L U P D AT E S Purple Line Extension Wilshire-La Brea Station under construction.

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