East Link Extension

The East Link Extension will provide passengers easy, traffic-free connection between the Redmond Technology Center and Downtown Seattle. The project includes approximately 14 miles of double-track light-rail transit, 10 stations, three parking garages, tunnels in downtown Bellevue, Mercer Island and Seattle and long-span bridges crossing over I-405 and over I-90.

HNTB led the initiative’s final design joint-venture team for the Bellevue to Redmond portion. The firm’s services included developing construction packages for the South Bellevue, Downtown Bellevue to Spring District, Downtown Bellevue Tunnel and Bel-Red portions of the line; developing design-build requirements for the Redmond portion; and providing design support during construction.

The first portion of the line is open with the second portion close behind. Traversing 6.6 miles and eight stations, the current segment runs between the Redmond Technology Center and South Bellevue.

Value Engineering

The firm 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 the client. 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 earth mining method of tunnel construction as the most cost-effective for the downtown Bellevue tunnel.

Upon final completion, the East Link Extension project will create new, reliable and accessibly connection between Seattle and Bellevue and Redmond.