Des Moines Memorial Drive South & South 200th Street Intersection Improvement

The City of SeaTac Public Works Department is partnering with the City of Des Moines to improve the intersection at Des Moines Memorial Drive S. and S. 200th Street. The construction project will begin on Monday, October 28, and is estimated to be completed by the end of December, 2020.

Starting Monday, November 4, and throughout the construction period, crews will be shutting down lanes along Des Moines Memorial Drive S. and S. 200th Street. Single lane closures will be between 9 AM to 3 PM.  However, some nighttime work is expected. 

Drivers are advised to find alternate routes during the entire construction period to avoid backups as these lane closures will impact drivers who utilize this stretch of roadway.

The City will be upgrading the roadways with multiple safety improvements for vehicle traffic and pedestrians. The City will be installing:

· A new traffic signal and traffic detection system at the intersection that will alert the signal when cars are waiting, which will improve traffic flow

· Left turn pockets which will improve the flow of traffic and make it safer to make left turns

· New sidewalks, concrete gutters, and curb ramps for wheelchairs and bicyclists

· New bike lanes to create a separation between cyclists and car traffic

· Crosswalks and curb ramps at the intersection to make it easier for people to cross the street safely

· New push-button crosswalk signals at the intersection to meet current Americans with Disability Act (ADA) standards

· Installation of new street lights to improve driver and pedestrian visibility

· The addition of retaining walls to prevent  roadway damage due to flooding and soil erosion

· Driveway improvements to create better access in and out of businesses and resident homes

Additionally, crews will be undergrounding utilities and replacing and upgrading the stormwater infrastructure. New catch basins will be installed along with larger replacement stormwater pipes. These upgrades will improve stormwater flow and limit the amount of flooding along the roadway during heavy rainfall.

King County Metro will relocate the pair of bus stops in this intersection for most of the project. However, there will be times when these stops may need to close to allow crews to complete improvements. Please visit King County Metro for additional information regarding impacts to Routes 122 and 156.

For more information on this project, please contact Engineering Manager Kamal Mahmoud, P.E., at  (206) 973-4742 or

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