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Kleinfelder leveraged the new Bridge-in-a-Backpack technology for the Royal River Bridge in Auburn, Maine. The Bridge-in-a-Backpack superstructure is composed of lightweight carbon-fiber tube arches that theoretically can be transported onsite in a backpack and filled concrete after installation. AN EFFICIENT SUBSTRUCTURE TO ACCOMMODATE LOADS The Bridge-in-a-Backpack solution required an efficient and effective substructure to accommodate the loads induced by the superstructure arches. Kleinfelder designed the abutments to resist traditional vertical loads for the spanning structure, plus the high horizontal thrust forces that the system’s flat arch shape places outward on the abutments. Because the arches are embedded in the abutment concrete, our structural engineers had to design the substructure elements to handle the potential bending moments created by the continuity. RAPID CONSTRUCTION AND LOWER COSTS Kleinfelder incorporated all of the substructure design parameters and developed a cost-effective abutment design that consisted of cast-in-place concrete pile caps on a single row of steel H-piles. This style of abutment used approximately 50 percent fewer piles, enabling more rapid construction and lower material costs. Kleinfelder’s design also eliminated the added expense of battering piles, which typically are required to resist horizontal loads. Futhermore, Kleinfelder developed an effective headwall design alternative that accommodates saturated soils, is aesthetically pleasing, and has a 75-year lifespan. Location: Auburn, Maine Project Cost: $1.1 Million Owner: Maine Department of Transportation An Employee-Owned Company | © 2013 Kleinfelder. All rights reserved. Bridge-in-a-Backpack Royal River Bridge Arches embedded in the abutment Pre-construction for concrete fill PROJECT RESULTS The Royal River Bridge was the first project to incorporate the innovative Bridge-in-a-Backpack solution, which saved time, money, and energy without sacrificing the integrity or lifespan of the bridge. Kleinfelder adapted the foundation and headwall systems to specific site constraints, applying this proven technology in new ways.
