TagWSDOT(123)

This traffic engineering report analyzes three signalized intersections along S 128th Street near SR 509 in the Sea-Tac area under projected 2032 No Action conditions during the PM peak hour. The study finds that the SR 509 ramp intersections are operating well over capacity, with an Intersection Capacity Utilization of 104.6% and an ICU Level of Service G, while the Des Moines Way S intersection operates more acceptably at 63.3% ICU. Overall intersection control delays range from approximately 19 to 27 seconds, with most approaches functioning at Level of Service B or C.

The Commercial Aviation Work Group held a hybrid in-person and virtual meeting on May 22, 2025, at Paine Field Airport in Everett, Washington. The agenda covered updates on a consultant RFP, an introduction of new non-voting members, and a presentation by Paine Field Airport Director Joshua Marcy on the airport's Master Plan. The meeting also included a 30-minute public comment period and time to schedule future 2025 meetings.

The Washington State Commercial Aviation Work Group submitted its first annual report to the Legislature in November 2024, summarizing early organizational steps taken since its July 2024 launch. The group, created to study airport capacity needs across Washington State over the next 20 years, held only two meetings in 2024 and remained understaffed, with just 13 of 19 required voting positions filled. Notably, Governor Inslee directed that expanding existing airports must be fully considered before any new airport site is selected, with SeaTac explicitly excluded from capacity expansion discussions.

This report analyzes existing traffic conditions around Seattle-Tacoma International Airport as part of the Sustainable Airport Master Plan (SAMP) Near-Term Projects Environmental Review. It examines 108 intersections—including 63 signalized, 41 stop-controlled, and 4 uncontrolled—along key routes connecting the airport to surrounding communities, focusing on the weekday PM peak hour (4–6 p.m.). Freeway segments of SR 518 and I-5 were also evaluated at WSDOT's request to provide a comprehensive picture of surface transportation conditions in the airport study area.

This technical report analyzes existing surface transportation and traffic conditions around Seattle-Tacoma International Airport as part of the Sustainable Airport Master Plan (SAMP) Near-Term Projects Environmental Review. It examines 108 intersections — including signalized, stop-controlled, and uncontrolled locations — along key travel routes connecting the airport to surrounding communities, focusing on weekday PM peak-hour traffic volumes. The study also includes freeway analysis of SR 518 and I-5 ramps and segments at the request of WSDOT.