Greenroads Pilot Project

South Park Bridge Replacement



Owner: King County, WA
Contract Price: $123.9 Million
Project Length: 0.42 Miles
Functional Class: Arterial
Greenroads Score: 47 Points


The South Park Bridge Replacement Project includes replacement of an existing 80-year old bascule bridge with a new bascule bridge crossing the Duwamish waterway in Seattle, Washington. The bridge is a principal arterial connecting the neighborhood of South Park and the central business district on the east to the Georgetown neighborhood on the west.  The existing structure is structurally deficient and has been closed to traffic since June 2010. Typical traffic loads are 20,000 ADT and expected to rise. The Duwamish waterway is an industrialized estuary of the Green River connecting with Puget Sound. Consequently, the existing bridge is built on hazardous and contaminated soil, requiring the treatment and disposal of all material excavated on the project. The scope of the project includes the construction of a new bascule bridge, approach structures, realignment of local city streets, drainage conveyance systems, landscaping, and several improvements to the neighborhood’s pedestrian and bicycle facilities. 

Project Flyer - South Park Bridge Case Study (143 kb)

Old South Park Bridge