November 20, 2025 1:00 pm

Justin Sieg, Project Director, KWH Constructors, Inc.
Chris Sweetgall, P.E., Project Manager, KWH Constructors, Inc.
Devin Altman, P.E., Senior Bridge Engineer, Project Manager, Jacobs

Presentation begins: 05:41
Q&A begins: 38:58

Presentation Documents:
Intro & News: Intro & News Slides
Presentation Slides: Presentation Slides - Pretty Rocks Longitudinal Launch

Description:

Denali Park Road within Denali National Park has had 47 miles of the 92-mile road closed to vehicular traffic since 2021 due to landslide activity at the Pretty Rocks area in Polychrome Canyon. To reopen this road, a single-span 475-foot-long Warren Truss bridge was designed to span the landslide zone. The challenge faced in designing the truss was incorporating an installation method that would be effective given the access restrictions. Steep rock faces, drop-offs, and lack of vehicular access meant that conventional steel erection procedures could not be used. The CM/GC team originally planned for a two-sided progressive cantilever with a high line, but when geotechnical conditions precluded this, the team pivoted to a one-sided approach and selected a hybrid launch methodology. The truss was erected as a progressive cantilever in two directions, and a temporary launch truss was then constructed inside it. This temporary truss was launched across the slide and used to pull the main truss into its final position.

Presenters:

Justin Sieg
Project Director
KWH Constructors, Inc.
jsieg@kwhconstructors.com

Justin Sieg is a Project Director for KWH Constructors, Inc. He has 16 years of experience in construction engineering and project management in complex bridge and water infrastructure projects. He is experienced in complex steel truss erection, moveable bridge installation – new and rehabilitations, and long span cast-in-place box girder retrofit and emergency stabilization. He received his Bachelor of Science in Civil Engineering from the University of Wisconsin – Madison.

Chris Sweetgall, P.E.
Project Manager
KWH Constructors, Inc.
csweetgall@kwhconstructors.com

Chris Sweetgall is a Project Manager at KWH Constructors, Inc. He has 18 years of experience in construction, specializing in engineering-intensive projects. His technical focus includes structural steel erection, crane operations, incremental bridge launching, and bridge temporary works. At KWH, he oversees structural steel installation operations and serves as Engineer-of-Record for complex steel erection projects. Chris holds B.S. and M.S. degrees in Civil Engineering from Columbia University and maintains Professional Engineer licensure in Alaska, New York, Oregon, Utah, and Washington.

Devin Altman, P.E.
Senior Bridge Engineer & Project Manager
Jacobs
devin.altman@jacobs.com

Devin Altman is Senior Bridge Engineer and Project Manager for Jacobs out of the Corvallis, Oregon office. He has over 20 years of bridge industry experience working on a wide range of projects including design, load rating, rehabilitation, complex analysis, and construction engineering services on a wide variety of bridge structure types, including simple and complex steel bridges, located in the USA and Internationally. Devin earned his Bachelor of Science in Mathematics from The Evergreen State College, and his Master of Engineering degree in Structural Engineering and Construction Engineering Management from Oregon State University.