3.1. National Projects
Washington SR 99 (International Boulevard)
The Project: International Boulevard (SR 99) is in King County, Washington, the most populous county in Washington. This section of SR 99 fronts Sea-Tac Airport. The airport and SR 99 serve as a gateway to the Puget Sound region for many visitors from around the world.
Location: City of Sea Tac, Washington (Suburb of Seattle)
Context Setting: Suburban
Road Classification: Principle Arterial
Stakeholders: WSDOT; SeaTac Community Planning Department; International Boulevard Committee; King County/Metro Transit; and Port of Seattle; Puget Power; General Public
The Process: The schedule, number of stakeholders with different interests, and complexity of the project required close coordination and a comprehensive but focused planning process. The process was designed to identify issues and needs, develop alternatives, and evaluate and establish the preferred alternative. The alternative selected included a center, raised median and other access management measures. Information on the planning work was provided at two open houses and in citywide news-letters.
The project design development process included consideration of three build alternatives and a no-build alternative. The alternatives included five-, six-, and seven-lane configurations for the roadway. The alternatives represented a spectrum of possible traffic improvements for International Boulevard. All alternatives provided sidewalks for pedestrians and widened curb lanes to accommodate bicycles and transit.
Optional design features were also developed that could be incorporated into any one of the three build alternatives. These design options included either a raised, landscaped center median or a median consisting of a continuous two-way, left-turn lane.
Lessons Learned: Alternative capacity improvements, HOV/transit treatments, access management measures, non-motorized mode options, signal system improvements, utility modifications, illumination concepts, and landscaping treatments were also developed.
Aesthetics were improved by planting trees along the sidewalks, special sidewalk paving patterns, a landscaped median and landscaped transitions with adjacent properties.
The most controversial issue for this project involved implementation of raised medians for access control and safety. The combination of speed (45-mph speed limit), high traffic volume, and number of lanes led to an agreement to replace the center two-way, left-turn lane with a raised median; driveway controls and consolidations were also included. Compromises included the incorporation of U-turn designs into key intersections and the development of two mid-block median openings.
The full case study for this project is available online at: http://www.contextsensitivesolutions.org/content/case_studies/480_99/resources/480_99/
