Los Angeles Metropolitan Transportation Authority has awarded a USD600 million contract to Eastside LRT Constructors, a JV of Washington Group International, Obayashi and Shimmick Construction for building of the 9.6 km East Los Angeles extension of the Gold Line. Running from the present Gold Line terminus at Union Station, it will run through the densely-populated areas of Little Tokyo, Boyle Heights and East Los Angeles. There will be eight stations at Little Tokyo/Arts District, Pico/Aliso, Mariachi Plaza, Soto Street, Indiana, Maravilla, East LA Civic Center and Pomona/Atlantic. A 2.9 km twin-bore tunnel under Boyle Heights including two underground stations need to be built. The extension is expected to open in mid-2009. Visit www.mta.net, www.wgint.com and www.ocac.com 33-34/04.For the twin bored tunnels (2.75 km long) to be built under the Boyle Heights neighbourhood of East Los Angeles, as part of the 9.6 km Gold Line eastside extension, the internal and external diameters will be 5.74 m and 6.27 m respectively. Two Herrenknecht Earth Pressure Balance TBMs will be used for tunnel excavation. The tunnels are expected to be constructed in alluvial soils consisting of dense to very dense coarse-grained soils, and stiff to hard low plasticity clays and silts. Groundwater levels vary from below to above the tunnel invert. Precast concrete bolted segments with 24 m of fabricated steel liners at Soto station connections. The number of segments per ring is five plus a key. They are being manufactured by Traylor Shea Ghazi Precast. Muck removal by locomotives and muck cars. There are two underground stations Boyle and Soto. The station platform lengths will be 82 m. The Boyle station will be the first underground station as the trains are running outbound from downtown Los Angeles. The excavation is about 183 m long by 18 m wide. A cut-and-cover tunnel section extends from the west end of the station to the west portal. The second station excavation in Soto is about 100 m long x 18 m wide. The cut-and-cover method of construction with braced excavation will be used. Initial support system consists of soldier piles and lagging, deck beams and concrete decking. Other structures will include two portals at the west and east ends of the tunnel. Construction of the east portal has begun. Six crosspassages will also be constructed between tunnels. Currently, the Boyle station is being excavated and soldier piling is near completion at Soto station. TBMs are in fabrication. Tunnelling is scheduled to begin in December 2005. Click us/89. Visit www.mta.net, www.metro.net and www.herrenknecht.com 24/05.