Washington State’s SR 520 is 50% Complete

May 3, 2021

The SR 520 Montlake to Lake Washington Interchange Bridge Replacement Project is halfway to completion.

In true partnership with the Owner, the Washington State Department of Transportation (WSDOT), Graham is delivering the first USD$455M Project within the greater USD$1.64B SR 520 Mega-program. The Montlake Project continues to progress well and is on schedule to be completed in the spring of 2023. Graham’s ability to self-perform multiple disciplines and major scopes of work has allowed the team to control the project’s critical path activities. With the exception of electrical, asphalt, and marine work, Graham is self-performing the following scopes:

  • Major pipeline construction
  • Traffic control
  • Earthwork / roadwork
  • Wall construction (CIP, MSE, Block Wall)
  • Montlake Lid construction / Bridge construction
  • Project-wide drainage
  • Major water treatment areas adjacent to Lake Washington
  • Bike/Pedestrian connections to the regional trail system

One of the unique scopes our team is self-performing is the installation of a 625 linear foot, 54-inch diameter water line, which includes boring under SR 520, the major artery to downtown Seattle. The Graham team is self-performing all excavation and trenching, pipe installation, commissioning of the new waterline, decommissioning of the old waterline, and staged backfill operations. The team has installed approximately 485 linear feet of pipe, with the remaining 135 linear feet scheduled for completion and commissioning by June 2021. This work remains on-schedule through a collaborative partnership with multiple stakeholders, including WSDOT, Seattle Public Utilities and the City of Seattle.

The project team also recently completed two successful weekend full closures of SR 520, to erect 114 of the 184 Montlake Lid girders. With excellent planning and execution, both weekend closures beat target productions, allowing the team to open the freeway ahead of schedule and without incident, providing major benefits to the traveling public, nearby neighbors, and WSDOT. To date, the team has placed 3,800 cubic yards of substructure concrete and successfully completed our first (400 cubic yards) of five deck pours. The team has approximately 2,000 cubic yards of substructure concrete remaining, and 128,000 sq. ft. of deck, which will be completed over the next two construction seasons.

The 2021-2022 construction seasons comprise a majority of the remaining self-perform work, including installation of 36,500 sq. ft. of MSE Wall spread across 10 different walls and construction of a Pedestrian Land Bridge, a 3-span, 75-ft wide bridge with 2,000 cubic yards of concrete, 30 wide flange girders, and 25,000 sq. ft. of concrete deck. Graham’s diverse and skilled workforce allows the team to efficiently plan and execute these operations, while mitigating risk and schedule erosion.

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