Dungeness River Railroad Trestle Replacement

Location: Sequim, WA
Client: Jamestown S'Klallam Tribe

In February 2015, during a large flood event, the Dungeness River avulsed laterally approximately 100 feet and destroyed two bents of the existing trestle. Otak completed the final design by the end of July 2015. The selected bridge type included four main spans of 185-feet each, which were prefabricated steel trusses with a concrete deck and a 30-foot wide section in the center that was used for an overlook area. The bridge piers had a buried pile cap with driven piles down to bedrock and a single concrete column supporting a hammerhead cross beam. A robust pier design insured stability after deep scouring below the pile caps, including lateral water pressures on debris buildup. The trestle replacement not only required a high level of engineering skill, but also an appreciation for the natural sciences, with focus on salmon recovery as well as the restoration of the popular trail linkage.