Polychrome Bridge, Pretty Rocks Slide Area

The Polychrome Area Improvements – Pretty Rocks Slide Bridge is a 475-foot modified Warren Truss, spanning the Pretty Rocks Slide in Denali National Park, Alaska. The project was procured using the CM/GC contracting method with KWH acting as a dedicated subcontractor to Granite Construction to fulfill the project's AISC Certified Erector requirement.

The remote site and complex geotechnical conditions required extensive project planning and outside-the-box engineering to introduce a unique launch scheme using a temporary truss within the permanent truss. KWH managed procurement of all superstructure-related materials and introduced Integrated Design Detailing to meet the project's compressed schedule.

In preparation for the bridge erection, KWH performed a trial assembly of the bridge at the fabricator's facility, Gunderson Ironworks in Portland, OR. The entire bridge was erected in two months, then disassembled and shipped to Alaska.

Construction took place over the course of three 6-month summer seasons with KWH crews living in work camps within the park.