Federal Way Link Extension

The Federal Way Link Extension (FWLE) project has earned an Envision Platinum Award from the Institute for Sustainable Infrastructure (ISI).  This recognition, the highest possible Envision award level, was received for the project’s achievements related to sustainable transportation, mobility and access, stakeholder engagement, infrastructure integration, and multiple other areas of sustainability. FWLE is only the seventh transit project in the U.S. to earn Envision Platinum.

The project extends light rail transit service 7.8 miles further south into King County and is part of a larger transit expansion in the Seattle metropolitan area, recognized as one of the most ambitious in the nation at present. FWLE demonstrated through its submission how the project responds to the specific needs of both host and adjacent communities to support sustainability, equity, and resilience.


“This award is a testament to Sound Transit’s long and deep commitment to sustainability and to the high levels of collaboration achieved with our project partners during challenging times,” said Sound Transit Chief Executive Officer Goran Sparrman. “We are proud of this achievement and look forward to many more sustainability milestones as we build public transit that connects our region to the places we live and work.”

“As a global leader in infrastructure, Parsons is transforming the rail and transit sector by providing innovative, tailored solutions that modernize transportation systems and deliver long-lasting, sustainable benefits to our clients,” said Mark Fialkowski, president, Infrastructure North America for Parsons. “Our contribution to the Federal Way Extension project represents Parsons’ combined engineering expertise and enterprise-wide commitment to sustainability. We are honored to be part of the team that achieved this award by creating a lasting, valuable public asset for the region and community.”

“Kiewit is proud to be the design-build contractor for Sound Transit’s Federal Way Link Extension, a project that showcases innovation in sustainable infrastructure. Strong partnerships, particularly with the community, are essential to our success,” said Kiewit Corporation Executive Vice President Doug Glaser.  “We would not be able to accomplish what we did without the remarkable people we had on the team, including the 400 local union tradespeople and the 200 subcontractors and suppliers who came together with our construction and engineering staff to achieve a common goal.” 

“We are honored to present the Envision Platinum award to the Federal Way Link Extension project, recognizing its outstanding commitment to sustainability, equity, and resilience,” said Kristi Wamstad, ISI’s Verification Director. “This achievement underscores the project team’s dedication to creating a transit system that prioritizes environmental stewardship and social equity while meeting the needs of the community.”

The project in brief

FWLE expands regional light rail south from Seattle-Tacoma International Airport (SeaTac) to Des Moines, Kent and Federal Way in King County, Washington. The route follows Interstate Freeway 5, from Angle Lake Station in the city of SeaTac, terminating at a new station — Federal Way Downtown (FWDS). Studies along the project corridor established the need for reliable, efficient peak and off-peak transit service to connect with the region’s growth centers. The corridor also has a high concentration of transit-dependent populations who need efficient and reliable regional transit connectivity, which FWLE directly addresses.

The line will include at-grade, retained fill, retained cut, and elevated structure guideway types. Construction of interim stations will be necessary, for continuity of service, at Kent/Des Moines, just south of the existing Angle Lake Station, and at South 272nd Street located to the north of FWDS. In addition, a maintenance facility will be constructed adjacent to FWDS to be used for vehicle inspection and interior cleaning. Parking, bus stops, and bike lockers and racks will be provided at the stations and other locations, further contributing to the project’s role in expanding mobility and improving connections to the regional multimodal transportation system. FWLE is forecast to be completed in 2026 and to raise ridership to approximately 29,000 – 34,000 daily riders.

Sustainability Highlights

Sustainable Transportation

The project helps deliver on the goal of providing a rapid, reliable, accessible, and efficient alternative for travel to and from the corridor and other urban growth and activity centers in the region, with sufficient capacity to meet projected demand.

Studies forecast increasing congestion on I-5 Freeway and on other key arterials in the areas surrounding the project. Without the project, commute time required for single-occupant drivers or riders on existing transportation services would be at least 20 minutes and 70 minutes more daily, respectively, to travel between downtown Seattle and FWDS.


As one indicator of Sound Transit’s sustainability leadership and commitment, the design-build contract for FWLE further stipulated the need for the project to attain at least an Envision Gold award level.  In addition, the design and implementation of FWLE aligned strongly with Envision and wider sustainable infrastructure principles and objectives, and the project team put in place systems and personnel needed to deliver on those commitments, including a comprehensive Sustainability Management Plan (SMP), updated at key project milestones. The SMP was supported by numerous agency-level policies Sound Transit’s Design Criteria Manual, which has a chapter dedicated to sustainability requirements.

Community Quality of Life

The project team’s submission demonstrated that FWLE meets or supports community needs and goals of increased access to transit, safer communities, and equitable regional growth. Social impacts on the host and affected communities’ quality of life were assessed and used to inform project decisions.  In addition, community values and concerns regarding protection and enhancement of views and local character were identified during the project planning phase and carried out through design and construction. Specific features, such as visual screening of construction lighting and design strategies to preserve the view of Mt. Rainier, were incorporated into the project requirements.

The Design-Build team has implemented measures during the construction phase to maintain appropriate access, ensure safey and wayfinding for pedestrians and vehicles during construction, as well as to mitigate light pollution, noise, and vibration.  Example measures include never closing the sidewalks on both sides of an affected street and communicating all upcoming lane closures and detours to stakeholders in advance via the Maintenance of Traffic task force.

Stakeholder Engagement
The stakeholder engagement process involved a broad set of stakeholders, including but not limited to cooperating federal, state, and local agencies, community organizations such as the Southwest King County Chamber of Commerce, and affected Native American tribes. The process included clear objectives, an active dialogue where stakeholder views were monitored, a two-way line of communication to reply to inquiries, and sufficient opportunities for stakeholders to be involved in decision-making. These opportunities included public meetings and workshops, community events, and briefings, providing availability to meet and discuss the project with interested groups.

Project outcomes were validated with stakeholder workshops and other public input and project decisions have been influenced by the feedback received.  For example, meaningful engagement with the City of Kent and Highline College resulted in siting the Kent/Des Moines station closer to Highline College, and improvements to pedestrian safety.

Stormwater Management
The project ensures that stormwater is managed effectively by constructing facilities that can handle heavy rainfall events. FWLE has measures in place to prevent excess runoff during different levels of rainfall. To cite one specific example, the project detains and treats 150% of 95th percentile 24-hour event through the construction of stormwater detention facilities.

Project-specific erosion, sedimentation, and pollutant control plans for construction activities were implemented: Construction Stormwater Pollution Prevention Plans (SWPPPs), Temporary Erosion and Sedimentation Control (TESC) Plans, and a Water Quality Monitoring Plan. The requirements in place for the project go beyond conserving the existing hydrological conditions to return areas to predevelopment conditions, therefore providing a restorative impact.

Infrastructure Integration

FWLE implements strategies to boost resilience that include track circuits for real-time monitoring systems such as track intrusion detection systems (TIDS) to enhance operational performance and prevent service disruptions. The project also improves systems integration by ensuring redundant transportation modes along the corridor, and diversifying methods to access destinations near the stations, such as Highline College. The project leverages its relationship with a larger infrastructure system for improved community integration and accessibility to public transportation.

About the Owner and Team

Sound Transit: Sound Transit, officially the Central Puget Sound Regional Transit Authority, plans, builds and operates transit for the central Puget Sound Region, throughout the urban areas of Pierce, King, and Snohomish Counties. Comprised of the guideway, three stations and associated facilities, FLWE moves forward in response to regional and local plans calling for high-capacity transit along the corridor consistent with the Puget Sound Regional Council’s VISION 2040 and Sound Transit’s Long-Range Plan.

Kiewit: Kiewit is one of North America’s largest and most respected construction and engineering organizations. With its roots dating back to 1884, the employee-owned organization operates through a network of subsidiaries in the United States, Canada and Mexico. Kiewit offers construction and engineering services in a variety of markets including transportation; power; oil, gas and chemical; water; marine; building; industrial and mining. Kiewit had 2023 revenues of $17.1 billion and employs 31,100 staff and craft employees.

Parsons Corporation: Parsons (NYSE: PSN) is a leading disruptive technology provider in the national security and global infrastructure markets, with capabilities across cyber and intelligence, space and missile defense, transportation, environmental remediation, urban development, and critical infrastructure protection. Please visit parsons.com and follow us on LinkedIn and Facebook to learn how we’re making an impact.


Name: Federal Way Link Extension (FWLE)
Location: Seattle Metropolitan Area, Washington
Award Level: Envision Platinum
Date: April 25, 2024
Owner: Sound Transit
Envision firm: Parsons Corporation
Project team members: Kiewit, Design-Build Contractor and Constructor; Parsons Corporation, Lead Designer
Total Project Cost: $2.45 Billion
Delivery Method: Design-Build
Phase: Construction
Project website: https://www.soundtransit.org/system-expansion/federal-way-link-extension