First TBM Breaks Through Metro Gold Line Eastside Extension in Los AngelesA Herrenknecht machine dubbed 'Lola' has completed a 2.75 km tunnel for the USD898 million eastside extension of the metropolitan region's Gold Line in Los Angeles. The TBM began burrowing the eastbound tunnel of the underground segment in February and reached the underground box of the east portal at First and Lorena streets in Boyle Heights on 14th November, 2006. Her twin 'Vicki' is a few weeks behind in the westbound tunnel and is expected to finish the westbound tunnel in mid-December. Each tunnel has a diameter of 6.4 m. Visit www.herrenknecht.comThe Metro Gold Line eastside extension will add 9.65 km of line and eight stations (two of which underground) from Union station east through Little Tokyo, the Arts District, Boyle Heights and East Los Angeles. Most of the route will be on the surface but the tunnels were needed because Boyle Heights streets are too narrow for rail cars. The twin tunnels were carved out from First and Boyle to First and Lorena streets at an average depth of between 15 to 18 metres. Each TBM weighs more than 1,000 tonnes and stretches 105 metres. As the machines were advancing, 30 cm-thick precast concrete tunnel lining were installed in the tunnels. On average, the machines dig 15 metres of tunnel a day. The TBMs were custom-built at a cost of USD10 million each.Construction of the Metro Gold Line eastside extension is being done by Eastside LRT Constructors, a joint venture of Washington Group International, Obayashi and Shimmick Construction. The extension is expected to open in late 2009. The trip from East Los Angeles to Union station will take 17 minutes. Click us/89. To view a video of the breakthrough, visit www.metro.net/news_info/press/metro_200v.htm. For more on the Metro Gold Line eastside extension in LA, visit www.metro.net/projects_programs/eastside/default.htm 47/06.