Sound Transit’s first high-capacity east-west transit project fulfills a decades-old transportation need for the region’s eastside residents and businesses
DESIGNER
2024
Two-mile-wide Lake Washington separates Seattle on the west from two of its largest eastside population and employment centers, Bellevue and Redmond. These eastern suburbs, respectively, are the site of an Amazon expansion project and home to Microsoft’s 60,000-employee global headquarters, among other major employers.
Existing roadways that connect the eastside cities with downtown Seattle are frequently congested. The bridges that traverse Lake Washington offer bus connectivity, but Sound Transit, Seattle’s public transit agency, projected that neither buses nor personal vehicles would sufficiently serve the long-term mobility needs of the city’s fast-growing eastside.
“Technology employment through this corridor is huge,” said Catherine Hovell, HNTB closeout manager. “With it comes the need to move people and connect them to the opportunities, housing and lifestyles they desire within that same economic space.”
In the early 2000s, Sound Transit began planning a regional light rail expansion including projects to serve the cities along the lake’s eastern shores. The 14-mile East Link Extension project, which adds a new light rail line from Seattle to Bellevue and Redmond, was approved by voters in November 2008. It is the region’s first high-capacity east-west transit project.
HNTB led a joint venture team, H-J-H Final Designer Partners, in designing the 7.2-mile Bellevue-to-Redmond portion of the electric light rail line. In April 2024, the initial 6.6-mile segment of the Link 2 Line opened, including eight stations. Initial counts show ridership around 6,000 riders each day, with service every 10 minutes, 16 hours a day, seven days a week. Ridership is expected to grow exponentially when the remainder of East Link, which will deliver riders across Lake Washington from Bellevue to downtown Seattle, opens in late 2025.
“This project fulfills an east-west transportation need that has existed for decades,” said Kevin Collins, HNTB project manager during design phase. “It significantly enhances mobility by connecting the regional power centers of Bellevue and Redmond and their jobs with cultural institutions, entertainment options and work on the west side of Seattle. It’s quite transformative for the communities it serves.”
Facilitating a first-time light rail project
Development of the East Link line included input from numerous stakeholders, including Bellevue and Redmond city leaders and residential groups. Because East Link represented the first implementation of a light rail system in those cities, station and rail line building standards didn’t exist.
Sound Transit and the project team collaborated extensively with city leaders through weekly meetings, sharing successful processes and outcomes in other cities as codes were being developed. City building and permitting personnel co-located in the project team’s office to facilitate and expedite the design approval process.
Intermodal connectivity was a key project goal. Coordinating with King County, where Seattle is located, the project team designed the Wilburton Station in Bellevue with a connection to the regional bicycle trail system the county is building.
“Considering the number of people who now commute by bicycle between Bellevue and Seattle, someone who doesn’t live close to a station could use the county’s regional bike trail system to reach the East Link system without having to drive,” said John Schlick, HNTB project manager during construction phase.
Secure bicycle parking is available at every station. Bikes are allowed on board 2 Line trains as well.
Working with its transit partners, Sound Transit redesigned the regional bus network to complement the new light rail system, removing overlapping routes and redeploying buses to serve expanded areas of the region. Three of the East Link starter line stations are incorporated into the regional bus system, allowing riders to easily transfer between express buses and light rail trains. All other stations are near bus stops, and three stations have adjacent park-and-ride facilities.
“This project fulfills an east-west transportation need that has existed for decades. It significantly enhances mobility by connecting the regional power centers of Bellevue and Redmond and their jobs with cultural institutions, entertainment options and work on the west side of Seattle. It’s quite transformative for the communities it serves.”
“This light rail line is going to change lives. It will connect people to education, jobs, recreation and each other, helping expand access to opportunity across our region. We wouldn’t be here without our incredible partners, like HNTB. Their expertise and dedication have been integral to making the vision of light rail on the Eastside a reality. For me, this is the culmination of years and years of work by many people and a realization of the promise we made to voters in 2008. For the Eastside, it’s the beginning of an incredible transformation that will benefit the community for decades to come.”
Tunneling solution
In response to Bellevue’s preference during the planning phase of the project, Sound Transit changed the light rail system’s alignment through the city’s downtown area from street level to a tunnel configuration that connects the East Main and Bellevue Downtown stations. H-J-H explored alternative tunneling methods that would reduce construction impacts.
The sequential excavation method (SEM) employed to build the approximately 2,000-foot-long tunnel allowed almost all work to be done underground. After dividing the tunnel into segments, construction crews used excavating equipment to remove small amounts of soil, one segment at a time. As each segment was removed, crews sprayed the tunnel’s sides, ceiling and floor with pressurized concrete, called shotcrete, and installed steel lattice girders for additional support.
Although the tunnel’s addition had the potential to elevate East Link project costs, SEM delivered affordability by minimizing utility relocations and business disruptions, reducing the need to reroute traffic through downtown Bellevue while construction took place. The tunnel was completed under budget and five months ahead of schedule.
HNTB’s expertise addressed complex design requirements at the Bellevue Station, where the platform is perched on the tunnel’s edge.
“There’s steep topography coming out of the tunnel, and the station immediately goes from underground to elevated,” Collins said. “The design includes pedestrian connectivity, accommodates a driveway into Bellevue’s City Hall and efficiently uses elevators and escalators. Finding the right solutions demanded both engineering and architectural design expertise.”
Value Engineering
HNTB also worked alongside Sound Transit, the City of Bellevue and other stakeholders early on in the project to provide value engineering services. As part of these efforts, the HNTB-led final design team conducted several design optimization studies that, ultimately, have led to significant reductions of costs for Sound Transit.
These studies included:
- Structural Optimization Study that simplified the aerial guideway, eliminated several large straddle bents through alignment refinements, and eliminated a long-span bridge crossing Bellevue Way SE.
- Tunnel Method Study that identified the sequential excavation method of tunnel construction as the most cost-effective for the downtown Bellevue tunnel.
Empowering transit-oriented development
Sound Transit’s transportation investment has unlocked economic development opportunities throughout the 2 Line corridor where residents and area visitors have access to improved regional connectivity. The HNTB-led design team worked with developers to enable transit- oriented development (TOD) near the new East Link line. The Spring District Station, located in the middle of a TOD area, presented a particular challenge.
The station is located below grade in a trench. In the original plan, horizontal underground tiebacks were specified as the most economical way to anchor the trench walls. The tiebacks, however, would have inhibited developers’ ability to construct building foundations.
To maximize the developable land around the Spring District Station, H-J-H designed an innovative and cost-effective concept that braced the trench on the inside using beams that cross the top and support the walls. That solution removed developers’ construction constraints and allowed them to develop right up to the trench’s property line.
Among the other TOD projects the starter line has spurred are 25,000 new Bellevue housing units that are either already built, under construction or in the permitting process. Light rail is a central element of the city’s overall growth strategy, which is expected to add 150,000 more homes and 185,000 more jobs over the next two decades
Connecting the region
When the East Link project is finished, it will connect more than 200,000 existing jobs in downtown Seattle, Bellevue and Redmond. By 2030, it is expected to serve about 50,000 daily riders on one of the Pacific Northwest’s most-congested travel corridors.
The 2 Line will cross Lake Washington via the Interstate 90 bridge, doubling the bridge’s capacity, reducing average travel time by 25 minutes per trip, eliminating 230,000 vehicle miles traveled per day and substantially reducing greenhouse gas emissions. The expected travel time savings alone are expected to be $65 million annually.
The 2 Line will have a transfer point at the International District/Chinatown Station in downtown Seattle, where travelers will be able to access the 1 Line that runs from downtown south to Seattle-Tacoma International Airport and north to Lynnwood.
“This light rail line is going to change lives,” said King County Councilmember and Sound Transit System Expansion Committee Chair Claudia Balducci. “It will connect people to education, jobs, recreation and each other, helping expand access to opportunity across our region. We wouldn’t be here without our incredible partners like HNTB. Their expertise and dedication have been integral to making the vision of light rail on the eastside a reality. For me, this is the culmination of years and years of work by many people and a realization of the promise we made to voters in 2008. For the eastside, it’s the beginning of an incredible transformation that will benefit the community for decades to come.”
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