Sound Transit selects Hoffman Construction and Arup for progressive-design build of new light rail facility
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Sound Transit selects Hoffman Construction and Arup for progressive-design build of new light rail facility
Arup is the lead designer delivering a new operations and maintenance facility for Sound Transit, which will support long-term transit operations across the Seattle region
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Chloe Ginnegar
Americas Media Officer
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Los Angeles
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Last updated: 3rd June 2026
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Seattle's Sound Transit Board has approved a $350m progressive design-build contract for the Operations and Maintenance Facility (OMF) South, a 70-acre hub for light rail fleet storage and repair. Hoffman Construction Company will deliver the facility alongside lead designer Arup and owner Sound Transit.
The new facility, to be located at South 336th Street in Federal Way, will house maintenance and operations equipment and staff as Sound Transit expands its regional footprint and fleet of light rail vehicles. This project will be critical to preparing for the planned Tacoma Dome Link Extension and building resilience for future Sound Transit operations.
This contract is Sound Transit’s first progressive design-build procurement, a project delivery method in which the owner, designer, and contractor collaborate early to develop the project’s design, cost, and schedule together. By aligning these elements upfront, the process reduces uncertainty, minimizes costly changes later in the project, and supports more efficient delivery of a complex scope of work.
“Hoffman has a long history of delivering complex transit projects with Sound Transit, and we’re honored to be selected for another critical piece of infrastructure for the region,” said Dave Johnson, Executive Vice President, Hoffman Construction Company. “This facility will play a key role in supporting system expansion, and we’re focused on delivering it safely, efficiently, and in close collaboration with the project team.”
“This complex facility is an opportunity for Arup to showcase what we do best — combining deep technical excellence with creative collaboration,” said Claire McConnell, Design Manager and Principal at Arup. “Having grown up in South King County, it’s particularly meaningful to be delivering this essential piece of infrastructure with Hoffman and Sound Transit.”
The team has been instructed to begin Phase 1 project definition, with a scope of work including final design, site preparation, roadway improvements, long-lead material procurement and construction staging and support facilities. Arup and Hoffman will work closely with Sound Transit through final design and early construction activities as the project advances.
The OMF South will provide space to store, test, commission and maintain at least 72 new 190-foot-long Series 3 light rail vehicles and will include a maintenance-of-way building and other support facilities. Once completed in 2032, the facility will employ more than 600 people and support long-term transit operations across the region