15th Ave. W. Arterial Asphalt/Concrete Overlay Program

From West Emerson to 1st Avenue North, Seattle, Washington

HWA performed a geotechnical and pavement engineering investigation along a heavily-trafficked, 2.9-mile segment of 15th Avenue West, from West Emerson Street to First Avenue North, in Seattle, Washington.

The objective was to visually inspect the various distress modes exhibited along the project alignment, estimate the amount of total pavement reconstruction required, and determine the strength of the existing pavement by conducting Falling Weight Deflectometer (FWD) testing and pavement coring. In addition, a geotechnical investigation was performed near the intersection of Mercer Place to assess the subsurface soils and recommendations for retaining wall designs.

Our work for this project consisted of detailed field reconnaissance, a FWD survey along the outermost traffic lanes, undertaking thirty core holes through the pavement, laboratory testing, performing pavement engineering analyses, and geotechnical reporting to provide parameters and recommendations for design of a retaining wall along Mercer Place. The investigation was challenging because of the heavy traffic which necessitated FWD testing and coring being undertaken at night.