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A most unlikely location of placemaking can be found spanning a busy transit corridor in Redmond, Wash., with 20 lanes of freeway and two tracks of light rail speeding beneath a bridge. The Redmond Technology Station Bridge, designed by Silman’s Lightweight Structures Group of TYLin (formerly FTL), stretches 1,100 feet, connecting two Microsoft campuses.
“Microsoft and the city of Redmond wanted a covered bridge joining the two campuses, which created both walking and bike lanes and covered seating areas for casual meetings along the route,” says Nic Goldsmith, FAIA, Lightweight Structures Group.
A key benefit in constructing the bridge at this location was its connection to Sound Transit’s Redmond Technology light-rail station, the SR 520 transit “flyer stop,” and the site’s connection to a regional bike trail and the software giant’s campuses (with some 47,000 employees) split by the roaring freeway. The bridge features a wide walking path, two lanes for cyclists and benches scattered across the length of the bridge, with native Northwest plantings flanking the rest areas, all covered by a fabric roof.
“The bridge was designed in different widths up to 50 feet and with two expansion joints,” says Goldsmith, “so we developed a continuous undulating canopy changing in both width and heights, creating low points for gatherings and high points for lighting and intermodal connections. We used a series of A-frames and arches to create a modular quality to the long expanse, allowing for tensile columns and fabric low points with customized water collectors to transform the tunnel-like quality of the spaces into an outdoor garden.”
With alternating up-facing and down-facing cones, the PTFE-coated fabric includes gutters and downspouts to protect users of the bridge. Downward cones also direct rainfall to areas where plantings are ensconced behind low protective edging that produces a wandering pathway for pedestrians alongside a straight pathway for bicycles. “The expanding details for the membrane at the expansion joints were developed to allow for the bridge movement to act independently,” says Goldsmith.
Project data
Client: Microsoft
Design and engineering: Lightweight Structures Group TYLin/Silman
Architect: AECOM
Sustainable engineering: Arup
Fabrication and installation: ETS
Project management: Kiewit
Fabric: PTFE glass by Chukoh Chemical Industries Ltd.
Placemaking: Very high
Decarbonization: Reduced weight; reduced vehicle traffic