SR 202 noise wall

Location: State route 202, between 180th and 188th avenues Northeast, Redmond

Owner/developer: WSDOT Bridge and Structures Office

Project team: Tri-State Construction, general and concrete contractor; CalPortland (formerly Glacier Northwest), ready-mix supplier

The noise wall project used both cast-in-place and on-site precast concrete construction. The wall’s design was the result of a public process where community members came together with architects and landscape architects to brainstorm ideas. The tree-pattern design was selected to complement the transition between a growing urban area and its rural surroundings.

Three different tree motif panel designs were used for economy. They were designed in a repeating pattern, while taking into account the contractor’s likely formwork setups. The same panels were used throughout the project by cropping the tree pattern as the wall height varied. Additional top bands of sandblast formliner finish allowed for varying wall heights. A fractured basalt finish was created as the wall’s base.

Although the contract was awarded with cast-in-place concrete construction, the contractor elected to build the tree motifs on-site in a precast method. Dowels and grout sleeves were used to connect the lower cast-in-place portion to the wall sections.

The foundation supporting the wall is a soldier pile retaining wall with a 4,000-psi design mix.