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AACE Seattle Section June 13th, 2019 Meeting

Executive Inn by the Space Needle

200 Taylor Avenue N.

Seattle, WA

PRESENTATION: Post Tensioning a Floating Bridge

PRESENTERS: Sepehr Sobhani and Brian Holloway

Sepehr Sobhani is a Principal Construction Manager working for Sound Transit on the Seattle to South Bellevue portion of the East Link Light Rail Extension. Previously he worked at WSDOT in both design and construction management working on notable projects such as the Alaskan Way Viaduct and the I-5 / SR18 Triangle project. He is a professional engineer, three time recipient of the Partnership for Excellence award from the Association of General Contractors, and was part of the project team that won the Award of Excellence from the Post Tensioning Institute. With almost 15 years of experience in the Puget Sound region, Sepehr has a track record of leading talented teams to successful completion of complex engineering projects.

Brian Holloway is currently the Corridor Design Manager for East Link, I-90 and Redmond Extension at Sound Transit. He directs and coordinate all technical aspects of these Light Rail projects leading the consultant design teams through these complex light rail projects. Mr. Holloway is both a licensed Structural (SE) and Civil Engineer (PE) in the state of Washington. In addition, Mr. Holloway holds a Washington license as a bridge inspector and is an Associate with the Design Build Institute of America. Throughout his career, he has worked in many aspects of civil and transportation project design and construction including, design, advanced seismic analysis, plan and specification preparation, construction administration, field inspection and construction support. Mr. Holloway has been with Sound Transit since 2014. Previously he worked at SDOT where he worked in Capital Projects and Roadway Structures as a project manager for bridge, trail, and transit capital projects and as the Design Manger for the Elliot Bay Seawall project.


The Homer M. Hadley (HMH) Bridge is one of the longest floating bridges in the world as part of the I-90 freeway across lake Washington. The decision to utilize this bridge as part of the East Link light rail extension makes this structure even more critical, taking the existing light rail system eastward approximately 14 miles, from downtown Seattle to the city of Redmond. This will be the first time light rail has ever been constructed on a floating bridge anywhere in the world. Given the vital nature of this multi-modal transportation corridor, Sound Transit agreed to add longitudinal post-tensioning to the pontoons of the HMH Bridge, extending the life of the structure by minimizing the current racking of these pontoons during adverse weather.