Sound Transit has accepted a bid for the Downtown Bellevue Tunnel Contract for the East Link light rail extension, and construction could begin as soon as next month.
Guy F. Atkinson Construction, LLC, a Colorado-based contractor which does business locally out of Renton, secured the contract with a bid of $121,446,551— 23 percent less than Sound Transit’s estimated costs. There were seven total bids.
The notice to proceed for construction should be issued in December. Construction is planned to last 4 1/2 years. The bid comes with a 10 percent contingency cost of $12,144,655, for a total authorized contract not to exceed $133,591,206.
Sound Transit was expected to give final approval on Thursday, Nov. 19.
The contract includes the work necessary to provide approximately 2,000 feet of tunnel from Main Street to Northeast 6th Street in downtown Bellevue.
The tunnel will begin south of Main Street on 112th Avenue Southeast and will travel northwesterly until it is parallel to 110th Avenue Northeast. It will continue north for 2 1/2 city blocks before emerging above ground as an elevated train next to Bellevue City Hall, where it will have a station. From there it will travel to the east, across I-405 and to a station in Wilburton near Overlake Hospital.
Work will include excavation, site preparation and final tunnel lining, as well as a center wall and access shaft on 110th Avenue Northeast.
Atkinson has worked on other major Washington projects, including on Stampede and Snoqualmie passes and bridges in Renton and Puyallup.
The Downtown Bellevue tunnel project is the first of seven major construction contracts for the East Link Extension. The East Link Extension project is targeting June 2023 for the first date of revenue service.
The East Link project will extend light rail service 14 miles from downtown Seattle to downtown Bellevue and Redmond. Stations will serve Rainier Avenue/I-90, Mercer Island, South Bellevue, Downtown Bellevue, Overlake Hospital, the Bel-Red Corridor, Overlake Village and the Overlake Transit Center.
Bids on the tunnel contract ranged from Atkinson’s $121 million to $169 million. Sound Transit’s engineers estimated costs at $156,929,508.
Total lifetime budget on the project has been estimated at $3.67 billion, $2.54 billion of which is slated for construction.
The tunnel is not a bore-driven tunnel like other Sound Transit projects, instead it will be a Sequential Excavation Method tunnel. This method carves out a section of tunnel and using natural rock and soil strength is able to support the tunnel by applying a layer of shotcrete and flexible support.
The tunnel has been one controversial aspect of the East Link project, with petitions and legal challenges for multiple areas of the light rail extension. These challenges and revisions moved back the proposed first date of service from 2021 to 2023.
