schlaich bergermann partner (sbp) is pleased to see the first passengers cross the newly completed aerial walkway at the Seattle-Tacoma International Airport. With an overall length of 780 feet, the soaring cable-stayed walkway is now the world’s longest structure over an active taxilane. Elevated to a height of 85ft above the tarmac, the enclosed pedestrian bridge allows for a seamless connection between the S Concourse and the new International Arrivals Facility (IAF) Grand Hall, along with stunning views of Washington’s Mount Rainier.
The bridge structure reflects an optimized king-post truss system with tie-down cables to minimize the thrust at the base of V-shaped piers. The bridge’s lengthy clear span over the taxilane is created by the two side span structures, which utilize V-piers with tie-down cables to act as a cantilever for the center span support. The side span V-pier structures also incorporate the escalators and a smaller bridge connection to the IAF. The structural system of the deck utilizes king-posts inclined toward the outside of the structure and supported by fully locked cables.
Given that Sea-Tac is one of the ten busiest airports in the U.S., the construction sequence was carefully considered during the design phase to minimize disruptions and used the U.S. Department of Transportation’s Accelerated Bridge Construction method. The resulting structure was fabricated offsite as 17 individual components, including the massive 1,560 ton, 320ft center span, which was lifted into place in one piece overnight.
The project team includes: schlaich bergermann partner (bridge designer), Skidmore, Owings & Merrill (IAF designer and collaborator on the bridge design), KPFF (bridge Engineer of Record), Clark Construction Group (contractor), The Erection Company (walkway erector), Supreme Steel (steel fabricator), Mammoet (heavy transport), and KCE Structural Engineers (peer review).