RCW 47.20.785
RCW 47.20.785: Design-build, progressive design-build, and general contractor/construction manager procedures—Public works projects.
(1) The department of transportation is authorized to use the design-build procedure, progressive design-build procedure, and any general contractor/construction manager procedure for public works projects. (2) For the first three general contractor/construction manager projects that the department delivers, the department shall pursue approval in accordance with RCW 39.10.280 . After three such approvals have been granted, the department is not subject to the approval requirements of RCW 39.10.280 .