Innovative Design at Cow Key Bridge

When unique situations call for exceptional solutions, BPA is here to provide an innovative approach to your project needs. An example of this is our work in Monroe County, where we developed plans and specifications for the bridge rehabilitation and span replacement of the Northbound and Southbound Bridges over Cow Key Channel (Bridge Nos. 900086 & 900125). The Cow Key Bridges are located on US-1 over Cow Key Channel and provide sole access in and out of Key West, FL. This project also consisted of jacketing a few piles, verification of the existing substructure, superstructure load rating, and associated roadway improvements.

The innovative bridge rehabilitation included three-span replacements using Florida Slab Beams (FSB) with Carbon Fiber Reinforced Polymer (CFRP) prestressing and Glass Fiber Reinforced Polymer (GFRP) reinforcing. The bridges are parallel, 360’ long, each with nine (9) spans. Bridge spans 2, 3 and 4 consisting of 40’ simply-supported beams are being replaced. This will be the first time a State Road vehicular bridge will utilize CFRP pretensioned slab-beams. By using CFRP prestressing strands and GFRP reinforcing in FSBs, degradation due to steel corrosion is eliminated with no reduction in AASHTO LRFD allowable tensile stresses. This innovative approach is highly beneficial as the FRP reinforcement eliminates the need for additional concrete cover, concrete additives, and waterproofing sealants for corrosion protection. Lightweight reinforcement allows for significantly lower labor and equipment costs because of the handling, as well as allows for longer service life and lower maintenance costs. This unique project is listed in the FDOT Transportation Innovation Initiative website.

Phase 1 of construction for the Cow Key Bridge rehabilitation is now coming to an end. This work has been completed under our FDOT D6 Districtwide Bridge Repair/Rehabilitation Plans Preparation contract.

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