The 220-foot-long Northeast 90th Street Bridge spans the Sammamish River, providing four lanes of vehicular traffic, two bicycle lanes and wide sidewalks that cantilever off the sides.

The bridge uses cast-in-place concrete with a conventionally reinforced concrete box girder supported by site-cast concrete arches and abutments. It is supported on concrete drilled shafts.

An unusual feature of the bridge — and reportedly a first in Washington state — is its arches that lean out of the vertical plane by 30 degrees. The arches integrate with the bridge’s box girder at their peak.

By constructing the box girder from cast-in-place concrete, the designers were able to customize its form. The sides of the box girder feature two orthogonal faces which integrate with the arches. The bottom features a single smooth slab with architectural grooves.

Another aesthetic feature of the bridge is the artwork found on its concrete abutment walls. A local artist created images of fish and other aquatic wildlife native to the area. The images were transferred to the face of the abutment walls through the use of custom concrete forms. A stainless steel ribbon was cast into the walls to represent a river surface.

The bridge uses 8,000 psi concrete instead of the typical 4,000-5,000 psi mix. The higher strength allowed structural engineer Entranco to uphold the architectural concept without increasing member sizes.