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East Link Light Rail - E330 Downtown Bellevue Tunnel

East Link Light Rail - E330 Downtown Bellevue Tunnel

Location
Bellevue, Washington
Client
Sound Transit
Designer
HJH
Contract Value
$121.5 million
Completion Date
2020
Market Sector
Underground
Mass Transit
Capabilities
Self-Perform

Sound Transit awarded Atkinson this $121 million contract to construct an underground light rail tunnel in downtown Bellevue. The E330 contract is one of multiple projects that will complete the East Link Light Rail Extension from downtown Seattle to Redmond.

The downtown Bellevue tunnel begins at the south portal near 112th Avenue SE and Main Street, runs under 110th Avenue NE for approximately one-half mile, then turns east near NE 6th Street towards the north portal—immediately adjacent to Bellevue City Hall and the Bellevue Transit Center.

The project demolishes existing structures and performs grading and utility relocation. The construction requires Atkinson's underground professionals to install temporary sound walls, retaining walls, and a portal box structure at the south portal. The scope of work also includes 585 linear feet of soil nail wall support of excavation and 325 linear feet of a permanent soil nail wall system. The tunneling operation includes approximately 1,985 linear feet of Sequential Excavation Method tunnel construction as well as tunnel pre-support, groundwater control, waterproofing, final lining, tunnel walkway, center dividing wall, embeds and conduits, and a mid-tunnel access shaft and adit.

Tunnel crown pre-support work included roadway removal, excavation, and replacement of fill materials with Controlled Low-Strength Material (CLSM) including sawcutting, temporary utility support, and surface restoration in 110th Avenue NE.

Once the tunnel is complete, Atkinson will construct the north portal, track, and tunnel appurtenances as part of our overlapping E335 Downtown Bellevue to Spring District light rail guideway and stations contract.