Let’s Bury I-5: An Urban Design Framework for Freeway Lids in Downtown Seattle

Abstract

The development of the American interstate highway system over the past 60 years has had a variety of negative impacts on urban neighborhoods. Where these freeways run below grade, one mitigation option and urban design strategy is to lid them over with bridge-type structures that help stitch together the urban fabric and restore connections. Seattle, Washington has lead by example with Freeway Park and the Washington State Convention Center spanning over Interstate 5 in downtown, and there are opportunities for additional lids in this area. Future lids must account for precedents, the form and characteristics of the surrounding physical realm, and the community’s variety of needs. In particular, downtown Seattle has a lack of useable public open space; with little land available for new parks, lids are an option for meeting this demand. This work proposes design guidelines for new lids. The guidelines are developed through a history of freeways in Seattle, an examination of notable plans and efforts since I-5’s construction, an inventory of existing and proposed lids across the country, three case studies, and a site analysis. The guidelines proposed here should be considered by the urban designers, engineers, landscape architects, architects, political leaders, and interested citizens who are involved in the design of future lids in downtown Seattle.