• Study

SR 518 Corridor Planning Study

Planning study news

This study is complete and the information gathered during this study will help WSDOT and its study partners prioritize practical concepts that will improve travel reliability on the SR 518 corridor and provide more transportation options for corridor users. Concepts were prioritized based on user feedback, data-driven safety benefits and cost effectiveness. This effort focused on finding smaller fixes and operational adjustments first so they can be implemented as funding becomes available. This may delay or remove the need for additional and more costly future improvements.

Fall 2018 - Summer 2020
$900,000 ($500,000 - M.V. Account & $400,000 local match from the Port of Seattle)


Through this study, we determined priorities for future highway work or transit service adjustments. and developed practical, cost-effective concepts to help improve trip reliability and safety along the corridor. Our study partners included Burien, Des Moines, SeaTac, Tukwila, tribes, King County Metro, the Port of Seattle, and Sound Transit. Concepts identified in the study were submitted to the Legislature in May 2020.

Map of the SR 518 corridor.