The Central Puget Sound Regional Transit Authority (Sound Transit) has awarded the joint venture of Stacey and Witbeck and Kuney Construction a $729.3 million contract to complete the design for and build the 3.4-mile Downtown Redmond Link Extension in the Seattle suburb of Redmond, Washington.
The light-rail project will extend the Blue Line from the Redmond Technology Station on the Microsoft campus to downtown Redmond and should be completed in 2024, one year after the $3.7 billion East Link's segment into the Microsoft station is finished. In addition to designing and building two new stations, the JV will also construct a 1,400-space parking garage, the overhead catenary system that will supply electricity to the line, traction power substations, train control and communications, special track work and utilities, as well as street and trail improvements.
The Sound Transit board also authorized an allowance of up to $50 million that will pay for the project team's review and funding of potential alternative concepts that are proposed during procurement. The authority acknowledged any possible additions of this kind, however, might increase costs.
Both Kuney Construction and Stacy and Witbeck previously have been selected to perform work on other Sound Transit projects. The authority gave Kuney a $93 million contract to build a segment of the East Link Extension. Stacy and Witbeck is part of a joint venture with Atkinson Construction with a $295 million contract for the East Link as well. Northwest Transit System Partners, a joint venture between STV and Mott MacDonald, was selected to oversee construction of the East Link in August 2017.
One of the most challenging elements of the East Link project has been the floating bridge segment across Lake Washington on the line's Interstate 90 route from Seattle to Bellevue, Washington. Sound Transit awarded the joint venture of Kiewit and Hoffman to add track infrastructure to the bridge.
Sound Transit recently provided a look into how the tracks are being installed on the bridge, according to Seattle radio station KIRO, and that work is being accomplished by securing the tracks with approximately 9,000 hanging concrete blocks and then "gluing" those blocks to the bridge deck using a non-shrink grout. John Sleavin, Sound Transit's deputy director for design, engineering and construction management, told KIRO that this method eliminated the need to drill about 18,000 holes in the floating bridge and will also help to disperse electrical current that might escape the light-rail system.
Project officials have also had to customize a train bridge that can transition into the infrastructure on each side of the bridge, operate with rising and dropping water levels and resist the wind and waves pushing on the bridge.