Tunnel Business Magazine

AUG 2018

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RELATED WORK - East Link Extension The $3.7 billion East Link Extension is a 14-mile, 10-station extension from the International District/Chinatown station south of downtown to Red- mond. The segment is mostly above ground, except for a short tunnel be- low downtown Bellevue. Guy F. Atkinson Construction was awarded a $121.4 million contract to build the 1,985-lf, 34-ft ID ovaloid, 12- to 48-ft de oject includes one maintenance shaft 17-ft diameter by 50-ft deep located near the midpoint of the tunnel, a connect- ing adit to enlarged tunnel section for permanent ventilation fans, and 250 lf of cut-and-cover structure. Crews are excavating soft ground consisting of glacial till and outwash gravel, using the sequential excava- tion metho top heading (three headings) as well as single side drift (6 headings). TP was issued Feb. 8, 2016, with substantial completion projected by y, the job was over 80% complete. Crews are utilizing two Liebherr 950 to excavate the tunnel, and Spraymec 8100 shotcrete ro- bot to place the shotcrete lining. The tunnel design team included obs Engineering Gr TB. Construction is ex- pected be completed by spring 2020. Revenue service for East Link Exten- sion is anticipated for 2023. TUNNELINGONLINE.COM C O V E R S T O RY 1 9 TBM: TUNNEL BUSINESS MAGAZINE // AUGUST 2018 Short Course in conjunction with . te Link Extension comprises 4.3 miles of twin- track railway from the existing University of Washington Station to a new elevated station a e te Station). Two new underground stations will be constructed a eet (U District Sta eet (Roosevelt Station). te Link Extension includes 3.5 miles of 18-ft,10-in. diam- eter twin-tube tunnel betwe eaf P eet and the University of Washington Station. A $440 million contr 125) was awarded to (Jay Dee/Coluc JV). It is the same JV that completed contract U-230 for the University Link program that con- nects downtown Seattle to the University of Washington Station, which opened for service in 2016. Sinc te Link began in 2014, the two tunnel boring machines, weighing 600 tons each, excavated more than 500,000 cubic yards of soil and installed 7,352 concrete tunnel liner rings. F ed a Hitachi Zos ed on the U-230 project, in addition to a refurbished Robbins EPB, which had – Northgate Link Extension

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