Bridging Challenges: Creative Solutions for the I-81 Bridge Foundation Design-Video

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KC Engineers presented the foundation design for a recently completed Syracuse bridge replacement. The original plan for one two-span bridge was revised through an alternate technical concept: the alignment shifted east and the bridge was split into two structures, avoiding water-main relocation and reducing construction impacts and cost.<br /><br />Bridge 7S required a 133-foot span with a 42-foot integral abutment, far exceeding typical New York State DOT guidance. Weak, weathered rock and karst conditions complicated pile design. Soldier-pile retaining walls were added in front of the abutments to reduce their height and enable standard abutment design. Tieback and deadman anchors, closely spaced bridge piles, and nearby structures created demanding coordination and construction constraints. Three-dimensional modeling helped resolve anchor conflicts, while geophysical surveys assessed rock conditions and pile support.<br /><br />Construction also involved pile deviations and variable depths, addressed through reinstallation and pile testing. Key lessons included adapting the layout, coordinating foundations carefully, and using integral abutments to reduce long-term maintenance and improve durability.

Keywords

bridge foundation design

integral abutment

alternate technical concept

soldier-pile retaining walls

karst conditions

pile testing