Precast Solutions - Winter 2009 - (Page 16) By Pittsburgh’s North Shore Connector uses precast panels Jonathan Barnes for an underwater rail tunnel. Photos courtesy of Technopref Industries UNDER THE ALLEGHENY Pi vided equipment such as a vacuum lift crane to move the segments ttsburgh is known as the City of Bridges, because of the many and a semiautomated finishing line used to prepare the segments with gaskets and packing material. A.C. Miller, in addition to its understanding of the local market, provided the partnership with its expertise in precast concrete production, experienced employees and its nearby production facility. The plant is about an hour’s drive from Pittsburgh, and the close proximity to the work site was crucial to completing the job on time. spans that cross its rivers and valleys. But in a twist of engineering fate, the largest, newest structure to traverse a river in the city is being built underground. The subterranean North Shore Connector, a 1.2-mile extension of Pittsburgh’s light rail system, part of which runs beneath the Allegheny River, relies heavily upon precast concrete segment rings for its structure. The segments are the exoskeleton of the dual-tunnel, underwater portion of the light rail structure and line the interior of the tunnels. Delivery of all 1,120 ring segments was to be completed by the end of 2008. Each ring is made up of seven precast segments weighing between 1 and 3 tons each. Once complete, the individual rings each weigh about 40,000 pounds. The North Shore Connector is extending Pittsburgh’s light rail system from the city’s downtown, under the Allegheny River, to stops on the city’s north side. The complex job brought together two diverse companies – one a family-owned precast manufacturer based in western Pennsylvania and the other a global construction firm based in France. A.C. Miller Concrete Products Inc. of Blairsville, Pa., worked with Technopref Industries Inc., a U.S. subsidiary of Demathieu & Bard, S.A., which oversaw production of the concrete segments for the tunnel. Technopref provided the formwork and its expertise in working on segmented precast concrete tunnels. Technopref also proUnderwater/underground tunneling work has a long and varied history in Europe, and many of the experts in this area of construction are from Europe. Technopref and its parent company have been involved in underground tunneling work for more than 20 years and have been working in the United States since 2000. But even with its depth of experience, Technopref couldn’t have predicted the great success its partnership with A.C. Miller. Working together, the two companies have consistently beat construction timelines for the $435 million Connector project. Due to the efficiency of the Blairsville facility and because of the uniquely slow nature of the tunneling process, the production of the concrete segments has outpaced mining work on the tunnel job. “The Connector job has a uniquely complicated tunnel alignment Hooking up 16 Precast Solutions | Winter 2009 www.precastsolutions.org http://www.precastsolutions.org
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