Cardno’s structures staff is working on a Cost Savings Initiative (CSI) for the CR 29 over Chokoloskee Bay bridge replacement in Collier County. This 225-foot-long, three-span bridge is currently in construction. The project involves phased construction using a temporary traffic signal to allow one lane of traffic over a navigable waterway.
The bridge was designed for current American Association of State Highway and Transportation Officials (AASHTO) wave loading standards. The CSI includes redesigning the bridge to resist the wave forces in a more efficient manner than the originally designed structure. The CSI is anticipated to save a total of $1 million from the original bridge design.
This project replaces the existing bridge on the causeway to Chokoloskee Island with a wider structure that will have two 12-foot-wide travel lanes with 8-foot-wide shoulders on each side and a single 8-foot sidewalk on the east (or bay) side. The sidewalk will be separated from the travel lanes by a barrier wall and will be connected to the existing asphalt path that runs along CR 29 in this area.
The new bridge deck will be at a higher elevation than the existing deck and the existing seawalls will remain in place to protect the banks and maintain a platform used by many for fishing.
Upon project completion, boaters will notice an increase in vertical clearance of about 3 feet and a wider passage due to fewer support columns.
The basic bridge geometry of the original 2015 design plans will be maintained (typical section, bridge stationing, span lengths, etc.). The focus of the redesign will be to recalculate the bridge reaction to the wave forces and develop the bridge design accordingly. This will include eliminating the current complex anchorage system, providing concrete keeper blocks on the bents, and redesigning the superstructure, substructure, and foundation.
The bridge superstructure will utilize prestressed FIB-36 beams with a cast-in-place deck and the bridge foundation will likely utilize 24-inch precast prestressed concrete piles (PPCP). The redesign will also modify the phased construction approach and eliminate the need for mechanical splicing of the superstructure reinforcing steel.
The project includes:
- redesign of the retaining walls around the bridge approaches using MSE walls.
- design of a new bulkhead wall in front of the existing bulkhead wall.
- relocation and redesign of the critical temporary walls to align with the revised construction phasing.