Fallbridge Subdivision Bridge Replacement
Advanced American Construction, Inc. working with BNSF Railway, replaced an existing railroad bridge with a 260’ thru-truss span. During the 3 years of planning and permitting, a float-in float-out method was chosen for the project to limit track closure while also reducing the environmental impact.
Crossing the Wind River in Home Valley, Washington, the existing span had to be prepared for float-out while the new span was being assembled in Portland, Oregon. Once the new span was erected in Portland on the Flexifloat assembly, it was towed up the Columbia River through the North Bonneville Lock before making its way under the Bridge of the Gods to the site. The tow from Portland to Home Valley took approximately 24 hours. Once on site, the ramps located across the bow of the barge assembly were removed so the platform could be positioned between the existing abutments.
The existing span was floated out by ballasting and deballasting 2 million pounds of water on barges located under each end of the 700,000-pound span. The new span was lifted approximately 30’ off the deck of the Flexifloat transport assembly using strand jacks. Once the span was elevated, the new 1.9-million-pound structure was floated into position and lowered onto its new abutments using the strand jacks. This bridge replacement operation resulted in only a 36-hour track closure.