We’ve begun using the term “Fourth Runway” to describe two large projects (SR-509 and the Sustainable Airport Master Plan) as one system, which they are. The two projects have always been part of a regional plan begun over fifty years ago to meet the strategic goals of the Port Of Seattle and regional planners. The construction of SR-509 will affect the communities are great deal. But starting in 2027 the projects will also increase flight operations at least 33% and cargo operations by 300%.