T.Y. Lin International (TYLI), a globally recognized full-service infrastructure consulting firm, announces that the Sound Transit E360 Guideway Bridge in Bellevue, Washington, has been selected for a 2021 Precast/Prestressed Concrete Institute (PCI) Design Award (Transportation/Non-Highway Bridge category). TYLI served as a Prime Consultant for the project, overseeing the final design for a two-mile segment of the overarching Sound Transit East Link Extension. Scope of work included the design of a 4,600-foot elevated guideway, track and special trackwork, and a pedestrian bridge over SR 520 to connect the Overlake Village Station to the Microsoft campus.
Now in its 58th year, the PCI Design Awards program recognizes design excellence and construction quality using precast concrete. The program demonstrates how designers are continuing to utilize high-performance precast/prestressed concrete to achieve sustainable, more cost-effective, aesthetically-pleasing, and quickly-constructed projects.
The $225 million East Link Extension expands a local existing light-rail system to connect the cities of Bellevue and Redmond, two major city centers. Delivered under a design-build contract, the project includes an 0.86-mile aerial guideway structure that consists of four parallel wide flange girders ranging in depth from 74 to 100 inches and 31 spans measuring 125 to 182 feet in length. Typical spans are 95-inch girders spanning 140 feet.
TYLI optimized the conceptual design of the Sound Transit E360 Guideway Bridge to develop a more cost-effective aerial structure and to utilize low-cost, high-resilience rail fasteners to reduce potential noise and vibration. The optimized design also minimized the number of foundations required, resulting in the elimination of five 9-foot shafts and a 65-foot-long post-tensioned straddle bent. The firm’s innovative approach benefits project stakeholders by preserving the right of way for future improvements to the adjacent SR 520 highway corridor, including the construction of a future highway off-ramp under the guideway.
Project challenges included bridge construction adjacent to a major highway in a metropolitan area with multiple road crossings, including a complicated overpass through a large intersection. The use of precast, prestressed, stay-in-place deck forms for the guideway structure and off-site fabrication minimized the number of road closures, increased the quality of the finished product, and expedited construction.
As lead designer during the bid phase, TYLI also led the team to develop an innovative redesign of the Overlake Transit Center. This resulted in the preservation of two acres of potentially developable land immediately adjacent to the transit center and a series of pedestrian bridges.
“The Sound Transit E360 Guideway Bridge required detailed project coordination with all stakeholders to ensure successful project delivery,” said Catherine Hovell, Ph.D., P.E., S.E., TYLI Vice President and Northwest Unit Manager. “On behalf of Sound Transit and the entire project team, T.Y. Lin International is very pleased that this vitally important light-rail extension project has been honored by the Precast/Prestressed Concrete Institute with a 2021 PCI Design Award.”
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