Project Profile: Tacoma Dome Link Extension (TDLE)

The Tacoma Dome Link Extension is a 9.7-mile light rail transit project advancing Sound Transit’s regional system expansion into the South Sound corridor. This critical infrastructure development will establish a high-capacity transit link between Federal Way, Fife, and Tacoma, integrating with the region’s existing multimodal network. The project focuses on deploying primarily elevated guideways to ensure operational efficiency and minimize surface-level disruptions.

Technical Specifications

The TDLE project’s core engineering involves the construction of an elevated guideway along the Interstate 5 corridor, a design choice intended to provide grade-separated transit for maximum service reliability and speed. The extension includes four new stations: South Federal Way, Fife, East Tacoma/Portland Avenue, and the Tacoma Dome multimodal hub. Station designs prioritize seamless integration with existing transit services, including Sounder commuter rail, Tacoma Link streetcar, and regional bus networks. A key supporting component is the new Operations and Maintenance Facility (OMF) South, designed to service and store up to 144 light rail vehicles, ensuring the operational readiness of the expanded fleet required for the ST3 system.

Key Takeaways

• Regional Connectivity: The TDLE closes a critical gap in the regional transit spine, providing a direct, reliable light rail connection from Pierce County to Sea-Tac Airport and downtown Seattle.
• Economic Development: By connecting major residential areas with employment centers like the Port of Tacoma and downtown Tacoma, the project is an enabler for economic growth and transit-oriented development around its four new stations.
• Congestion Mitigation: With a projected daily ridership of 27,000-37,000 by 2040, the extension offers a sustainable alternative to single-occupancy vehicles, directly addressing traffic congestion on the I-5 corridor.

Frequently Asked Questions (FAQ)

When will the Tacoma Dome Link Extension open?

The Tacoma Dome Link Extension is currently projected to begin operations in 2030. This timeline is contingent on the construction schedule, which officially commenced in 2025 following the completion of extensive environmental reviews and final design approvals.

Who is building the Tacoma Dome Link Extension?

The project is owned and managed by Sound Transit, the regional transit authority for the Puget Sound area. Sound Transit is working with a team of expert partners, including the global engineering firm HDR for primary design and planning, along with specialized consultants like Parametrix and Schemata Workshop.