The Tacoma Dome Link Extension will extend the regional rail system by approximately 16km primarily through elevated tracks. Credit: Parametrix.
The future Fife and South Federal Way stations will include new park-and-ride facilities. Credit: Sound Transit.
The TDLE is expected to enter service in 2030. Credit: Sound Transit.

The Tacoma Dome Link Extension (TDLE) is being proposed by Sound Transit to provide fast and reliable connections to different destinations in the South Sound region in Washington, US.

The project will extend the regional light rail system by nearly 16km between Tacoma and Federal Way in Washington. It will provide direct access to downtown Seattle and SeaTac Airport.

The light rail extension is a part of the regional Sound Transit (ST3) ballot measure, which was approved by voters during the elections in Seattle in November 2016. ST3 involves the expansion of the regional mass transit system over a period of 25 years.

The TDLE project, which is currently in the planning phase, will include mostly elevated tracks and four new light rail stations in the areas of Fife, Tacoma Dome, South Federal Way and East Tacoma/Portland Avenue, with connections to the regional light rail network.

The draft environmental impact statement (EIS) is underway and is expected to be published in 2021. The selection of the final alignment and stations is anticipated in 2022 while construction is scheduled to start in 2025. TDLE is expected to start operations in 2030.

Details of Tacoma Dome Link Extension project

The Tacoma Dome Link Extension will provide commuters with fast and frequent connectivity to residential and job centres across the South Sound region. It will link the Federal Way Transit Center Station, King County, to the Tacoma Dome Station area in Pierce County.

The Tacoma Dome station is planned to be developed as a multi-modal transit hub. It is expected to be integrated with Sounder service, Pierce Transit, Amtrak, Tacoma Link and Sound Transit buses.

The four stations in the link extension will offer connections to other transit options such as Tacoma Link, Intercity Transit, and King County Metro.

The project will create dedicated areas for drop-off and pick-up of commuters and the stations will be accessible to people arriving on foot and by bikes and other modes of transportation. The Fife and South Federal Way stations will feature two new parking facilities with approximately 500 spaces each.

The preferred alternative at the Tacoma Dome station is Tacoma 25th-West. Other alternatives being studied in the draft EIS include Tacoma 26th Street, Tacoma 25th-East, and Tacoma close to Sounder. The route along E 26th Street, between E Bay Street and Portland Avenue E, is the preferred alternative for the Portland Avenue station.

The planned City Center, located between 12th Street E and 15th Street E, was identified as a preferred alternative location in the Fife area, while SF Parkway was chosen in the South Federal Way area with the station location at Enchanted Parkway and 352nd Street.

Sound Transit is also planning to build an operations and maintenance facility (OMF) to support the extensions under the ST3 programme. The proposed OMF South will meet the cleaning, storage and maintenance needs of the company’s fleet of trains and have the capacity to accommodate 144 vehicles.

Project timeline

The project was in the alternatives development phase between 2017 and 2019. The development phase included technical analyses and recommendations from advisory groups, tribal representatives and elected officials to advance the project alternatives.

The early scoping for the project started in 2018 and was followed by the evaluation of alternatives. The report for the final scoping was performed between April and May 2019 and was published in May 2019. The Sound Transit Board identified alternatives to study in the draft EIS, in July 2019. The alternatives were identified after 18 months of interactions with the public and other stakeholders. The draft EIS will study the potential impact of the project on the environment and existing properties in the region and identify mitigation measures.

The Sound Transit Board will confirm or change the preferred alternative in 2021. The final EIS is anticipated to be published in 2022 and the design phase between 2022 and 2025 will include the design of final route and stations, obtaining approvals for construction and land use, and land acquisition.

In March 2020, land and water surveys were started in Milton, Fife, Federal Way, and Tacoma. The fieldwork activities are intended to study conditions in and around the areas of the preferred routes and station locations.

The project team is conducting drilling activities to collect soil samples for the design and engineering work. Fieldwork is also expected to include noise and vibration monitoring, as well as surveys of streams and wetlands. The team is also working with property owners to gather the information that is required to plan and design the potential light rail alignments. The light rail alignments will be studied in the environmental review process.

Benefits of Tacoma Dome Link Extension

The regional light rail will allow commuters travelling from Fife to reach Tacoma Dome Station in six minutes. The travel time between South Federal Way and Tacoma Dome Station is expected to be 20 minutes. The trips from Tacoma Dome Station to Sea-Tac Airport would take approximately 35 minutes, upon completion.

The system is projected to handle 27,000 to 37,000 of riders per day by 2040. The project will address the increasing roadway congestion in the South Sound while meeting existing and future demand. It will also provide better connectivity between the South Sound and the rest of the region.

In addition, the light rail transit system will allow the state to meet environmental and sustainability commitments.

Contractors involved

Engineering firm HDR was awarded a contract to support the planning of the TDLE project and the new maintenance facility, in December 2017.

The contract includes planning, preliminary engineering, and environmental services. A contract modification was signed in June 2019 to provide project development services for OMF South within the TDLE project.

Parametrix Design is the sub-consultant partner to HDR and is performing the environmental study. Schemata Workshop collaborated with Parametrix on the alternatives development phase.