Surveying and Geomatics

Transportation Infrastructure

Alaskan Way Viaduct and Seawall Replacement Surveying and Mapping

Location: Seattle, Washington

This is a joint project between the Washington State Department of Transportation (WSDOT) and the City of Seattle to improve the existing SR 99 corridor in downtown Seattle, which is partially served by the 5-mile-long Alaskan Way viaduct and the seawall along Elliott Bay.

In support of the preliminary design phase of this project, DEA surveyors completed a control network, base and topographic mapping, bathymetry and surveying for the length of the seawall, and field surveys to identify hydraulic locations and obtain pipe invert elevations. The horizontal control was integrated into the city's network.

DEA provided mapping that included traditional terrestrial ground mapping, CYRA 3D digital scanning, and low altitude aerial mapping. In addition, DEA provided right-of-way plans to WSDOT specifications for the entire length of the new route, computing boundaries and areas, and preparing land descriptions and property ownership research for future right-of-way acquisitions. The project affected approximately 200 land parcels.