OAC | Portfolio: PM&CM - Transportation

SR 509/I-5 Corridor	SeaTac Airport
JFK Airport	Boston Central Artery
Port of Seattle

OAC provided value engineering (VE) services for the SR 509/I-5 Corridor Completion, which received AASHTO’s 2003 value engineering honorable mention for “most value added during engineering.” The VE team included representatives from HNTB, Rosewater Engineering, Department of Ecology, City of SeaTac, King County Department of Natural Resources, Port of Seattle, National Marine Fisheries Service, and City of Kent.

The project was designed to improve regional highway connections by extending SR 509 3.2 miles to Interstate 5 and includes:

An interchange at I-5 and SR 509

Improvements to 6.67 miles of I-5

Major modifications to the I-5/SR 516 interchange

A south access road to SeaTac Airport

Sixteen drainage basins, including fish habitat in Des Moines Creek

The VE study reviewed storm water and staging aspects of the projects. With an overall project cost of $102 million, $39 million (38 percent) in cost savings were realized through VE. The value of the project was enhanced by:

Following Ecology guidelines for compensatory storm water treatment

Utilizing Level 1 flow control for the improvements, based on King County’s Basin Plan for the Des Moines Creek watershed

Sequencing construction in five stages in 52 months, rather than six stages in 63 months, resulting in an 11-month reduction in schedule

Encouraging bid competition and design-build

Building fewer storm water facilities, resulting in maintenance savings

Value Engineering

Owner: WSDOT
Location: Kent, Washington
Project Cost: $102 million