BNSF Bridge 81.4

HNTB served as the prime designer and construction manager for the BNSF 81.4 Bridge across the Cowlitz River, a critical commercial and freight rail infrastructure link in a remote area of Washington state. With no alternate rail routes nearby, the nearly 1,100 feet long bridge provides a convenient, safe river crossing for up to 50 trains per day.

The more than one hundred-year-old bridge reached the end of its service life and needed to be replaced to ensure reliable service. HNTB evaluated a range of replacement options and ultimately selected an offline alignment due to high train traffic. The team was able to streamline construction and reduce project costs by leveraging the CM/GC delivery method and coordinating closely with the contractor.

The rugged, natural landscape posed geotechnical challenges. The team addressed these challenges with a bridge design that features 143’-4” and 207’-6” long deck plate girders supported on large diameter drilled shafts with rock sockets and box beam approach spans supported on socketed H-piles.  The 207’-6” deck plate girder span is one of the longest spans on BNSF’s system for this span type. The superstructure utilized weathering steel to provide long-term corrosion protection and withstand the heavy rains and winds that are common to Vader, Washington.

HNTB’s design team coordinated closely with local permitting agencies as well as with the local Cowlitz and Chehalis Confederated tribes, whose tribal lands were affected by the project. Early and often in the process, the team met with tribal representatives to understand the potential impacts on the tribes’ land, fishing access and historical or cultural resources.

BNSF 81.4 provides a long-term solution for safe and reliable rail service in western Washington.