Figure 13 - Seattle Sound Transit Light Rail project aerial wiew, (photo courtesy of PCL Construction Services).

The Seattle Sound Transit Light Rail Project, Tukwila Segment, consists of 4.9 miles of twin track light rail line, including 4.6 miles of elevated precast segmental guideway. A view of the project is presented in Fig. 13. The contract was successfully bid by PCl Construction services in February 2005. Since that time, an additional extension has been added to the contract, bringing the total amount to approximately $277 million. The first large scale precast segmental project for the state of Washington, the majority of the elevated line consists of simple spans with a typical length of 120' erected using span-by-span construction with an overhead gantry. The 7' deep box-girder utilized a new cross-sectional shape with a minimized bottom slab, and tendons that are both external and internal to the section. The extension to the project, executed in September 2006, will include an additional 2447' of precast segmental superstructure. Typical spans are also 120' and simply supported. There are two additional longspan, balanced cantilever structures. The longest is 679' between expansion joints, with a main span of 259'. The structure erection completed on schedule this fall and crews are now focusing on completing the plinth and rail construction on top of the deck. The overall project is scheduled to complete by the end of the first quarter of 2008. Erection included constructing balanced cantilevers over major arterial highways. The balanced cantilever design allowed the contractor to construct a major structure without affecting traffic, something also new to the region. The construction for the project has been very high profile in the Seattle area and has given local citizens a tangible indication that this long desired light rail project is progressing rapidly. The use of the expeditious means of construction of this precast segmental construction is a significant reason for this impression. From end to end overall erection was completed in 24 months, including the additional work added late in the project. Owner: Sound Transit Designer: Hatch Mott MacDonald Group Contractor: PCl Construction services, Inc. Construction Engineer: YY Lin International Construction Engineering Inspection: YY Lin International Formwork for Precast Segments: EFCO Corp. Erection Equipment: Deal Post-Tensioning Materials/Stay Cables: Schwager Davis, inc. Bearings and Expansion Joints: the DS Brown Company (Expansion Joints), RJ Watson, Inc. (Bearings) Epoxy Supplier and Prepackaged Grout: Sika Corporation