A plan to improve roadways and expand mass transit—easing congestion in the central Puget Sound region

Projects > South Corridor

In the South Corridor, which includes the urban areas of south King County and Pierce County, traffic is worsening as the region’s population continues to grow. South King County is home to nearly 40 percent of King County’s population. By 2020, Pierce County’s population will increase by more than 200,000 people, putting even more pressure on the transportation system. In addition, nearly 30 percent of Pierce County’s workers commute to jobs in King County.

From Orting, Lakewood and Fort Lewis to Renton, Tukwila and Burien, the region's economic well being depends on its roads and transit infrastructure.  

In the South Corridor, the Roads & Transit plan would:

  • improve roads such as SR 167, I-405, SR 509 and the Orting Highway (SR 162) to make commutes safer and more reliable
  • light rail would extend south from Sea-Tac Airport to the Tacoma Dome

The projects proposed for the South Corridor, and the benefits they provide, are described below.

The proposed Roads & Transit investment package would link housing and employment centers so that workers can get where they need to go and freight can move efficiently. This is intended to help create jobs, reduce congestion, and improve traffic safety and mobility in the South Corridor.

What is proposed for the South Corridor?

Proposed transit investments

Light Rail Extension: From Sea-Tac Airport through Des Moines and Federal Way to the Tacoma Dome. Connects Pierce County to the regional light rail system.

Burien Express Bus Parking Garage: Builds more parking to provide easier connections with regional and local buses, such as Sound Transit Route 560, and to support local development.

Tukwila Permanent Sounder Station: Builds permanent station facilities, a bus loading area, and a new parking area with up to 400 stalls, making it easier to connect to Sounder commuter rail and buses.

Auburn Sounder Parking Garage: Builds new garage with up to 500 more stalls, making it easier to connect to buses and Sounder commuter rail.

Sumner Parking Garage, Pedestrian Bridge: Builds new garage with up to 400 stalls and a pedestrian bridge, making it easier to connect to Pierce Transit and Sounder commuter rail.

Puyallup Sounder Station Garage, Pedestrian Bridge: Builds new garage with up to 600 more stalls and a pedestrian bridge, making it easier to connect to Pierce Transit and Sounder commuter rail.

Proposed road investments

I-5/SR 509 Corridor Completion and Freight Improvement Project: Completes the missing link between SR 509 and I-5, providing a south access road to Sea-Tac Airport and connecting the Port of Seattle to the Kent/Auburn manufacturing and distribution center. Adds general purpose lanes to I-5. Improves freight mobility, removes trucks from I-5, and reduces Southcenter Hill and I-5 congestion.

SR 167/I-405 Interchange HOV to HOV Direct Connection Project: Builds direct HOV-to-HOV connection between SR 167 and I-405 to eliminate weaving and address the most congested interchange in the state. Connects I-405 HOV lanes and proposed SR 167 High Occupancy Toll (HOT) lanes.

SR 167 Green River Valley Corridor Congestion Relief Project: Completes HOV/HOT lanes on Kent/Auburn section of SR 167. Adds new general purpose lanes in key locations to reduce congestion and increase safety.

I-5/SR 18 Federal Way Congestion Relief Project: Reconstructs interchange by adding direct freeway to freeway connections between I-5 and SR 18 and providing a more direction connection to the Enchanted Parkway (SR 161). Relieves back-ups and eliminates dangerous weaving to improve safety at one of the worst chokepoints in the state.

South I-5 Mobility Project: Builds direct southbound ramp from I-5 to Tacoma Mall Blvd. near the Tacoma Mall to improve traffic flow on I-5 and local city streets. Installs I-5 Intelligent Transportation System Technology facilities.

SR 167 Tacoma to Puyallup Project: Provides new north-south alternative to I-5 by connecting SR 167 where it currently dead ends in Puyallup to SR 509 at the Port of Tacoma. Improves traffic and freight mobility, accommodates port expansion and economic development.

SR 410/SR 162 Congestion Relief Project: Adds capacity to Orting Highway (SR 162) between Sumner and Orting by replacing the SR 410 interchange, widening the roadway, and providing sidewalks from SR 410 to Puyallup River. Also improves the Traffic Ave. Bridge.

I-5/SR 704/176th Corridor—Cross-Base Highway Non-motorized Investments

Non-motorized Investments

Updated 06-28-07