Construction of the Beacon Hill Station in Seattle, WA, is presently underway. This project involves some of the deepest and largest scale SEM tunneling work ever undertaken in soft ground. This paper provides an update of the construction activities at the Beacon Hill Station site and summarizes some lessons learned so far.rnThe final design of the Beacon Hill Station and Tunnels was completed in December 2003. The project was awarded to Obayashi Corporation at a contract price of $280 M. Notice to Proceed was given in June 2004.rnTo date, the contractor has completed preparatory work at the portals as well as the diaphragm walls for the station shafts and headhouses. SEM tunneling is underway and scheduled to be completed in late 2006. The design of the large diameter station tunnels is based upon a complex sequence of multiple drifts with an array of pre-support and ground improvement measures. To assist Obayashi in successfully employing these measures to deal with the highly variable ground, and ensure that construction is carried out in accordance with the design intent, the designers provided a technical support team consisting of experienced senior SEM engineers, engineering geologists, shift engineers and inspectors.
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