Overcoming several challenges, a design-build team has made significant progress on the $171 million Brooks Bridge Replacement Project in Okaloosa County, Florida, with plans to finish the Florida Department of Transportation (FDOT) job on time in January 2028.
“The job's progressing very well,” said Evan Lawrence, Division Manager for Superior Construction, the design-build lead for this project in Fort Walton Beach. “We're slightly behind on schedule right now, but we have implemented some additional crews and resources to start making up the time on the job.”
WSP Design Project Manager Matt Durshimer, based in Tampa, Florida, also credits the Florida Department of Transportation, which he said has been “excellent to work with.” WSP is the engineering partner for this project.
The two new parallel, three-lane bridges will replace an existing four-lane structure, carrying traffic both east- and westbound. The new bridges over the Santa Rosa Sound and Gulf Intracoastal Waterway will be longer, each about 2,111 feet — nearly 800 feet longer than the existing structure. The new bridges will increase bridge capacity. Vertical clearance will increase over the existing 150-foot channel from 50 feet to 65 feet, the current U.S. Coast Guard regulation.
WSP designed the new bridges to withstand hurricane force winds and strikes from barges in the water. The piers sit outside the channel to minimize the risk of a vessel striking them. Each structure contains 84 30-inch square concrete piers over water and 24-inch piles over land, with 12 pier caps on each bridge.
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The new bridges will include 10-foot-wide inside and outside shoulders and a 12-foot-wide shared-use path for pedestrians and bicyclists, with barrier walls separating it from vehicular traffic. Each bridge features two 80-foot-long scenic overlooks, with benches and shade structures.
The current bridge carries about 66,000 vehicles daily between Fort Walton Beach to Okaloosa Island. It has narrow, 4-foot-wide sidewalks, separated from vehicle traffic with a curb. It opened in 1966.
“The existing Brooks Bridge has been around for several decades, and it's approaching the end of its service life,” Durshimer said. “The project was kind of brought to the forefront about 10 years ago or so, when the existing bridge was struck by a vessel.”
A crane sitting on a barge smashed into the bridge’s superstructure beams and broke the only water line to Okaloosa Island. The existing bridge also carries a sanitary sewer line and fiber optic lines for several utility owners.
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“Because of all the different utility owners crossing from Fort Walton over to Okaloosa Island, it has been a substantial utility relocation effort that is still ongoing, well over two to three years into construction here,” Durshimer explained.
The approach spans feature prestressed concrete I-beams, with a concrete deck. The main 2-foot span uses a post-tensioned splice girder, with heated wax to fill the tendon ducts — the first in Florida.
The replacement project also includes intersection improvements and upgrades to comply with the Americans with Disabilities Act, new stormwater retention ponds, and a new connector road on Okaloosa Island. Currently, it is an at-grade intersection. The team will build the new bridges 15 feet higher than the existing structure, which creates no problems on the Fort Walton Beach side. But work was needed on the island.
“In order to accommodate that larger vertical clearance, we now have turned the at-grade intersection into an overpass,” Durshimer said. “And then at the foot of the bridge, once we get down back to ground level, we have two connector roads — a north connection and an eastbound connector. Those connector roads will restore the same functionality that the existing intersection has.”
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The team received a notice to proceed in July 2022, which kicked off the design phase. Superior began some early construction in November of 2022.
Multiple issues challenged the designers and builders of this project.
To begin, the maintenance of traffic plan included keeping vehicles on the existing bridge until the new westbound bridge is complete in mid-2026. Then all traffic will switch to that new bridge. Lane closures are limited to 9 p.m. to 5:30 a.m. Some nighttime pile driving restrictions allow for aquatic life to peacefully travel underneath the bridge outside of construction hours, said Durshimer.
The teams provided marine life protection and avoided impacts to adjacent wetland areas and any damage to small tooth sawfish sea turtles. They also employed lighting restrictions to protect the sea turtles by using amber-colored light fixtures.
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Superior will demolish the old structure once traffic shifts to the new westbound bridge and work can begin on the new eastbound bridge. But in order for that to happen, Superior had to temporarily fill in the median to create a wide enough road to carry all of the traffic.
The area’s stiff sands presented challenges during pile driving. It will again on the eastbound bridge.
“When you start pile driving, what we get to is some high stresses on the pile, so that just slows down the driving,” Lawrence said. “We have to give it more wait time, relaxation, then drive again. That just adds a little bit of time to the operation. However, they're all taking up around where we anticipated them to, at the capacities that are required in minimum tips as specified in the plan. It's challenging, but we have a good team out there that's definitely learned through the process on this job. [It’s a] very unique condition to drive pile in. They've overcome that in this first phase.”
According to Durshimer, those dense sands provide good bearing.
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“Because this is a bridge over water, we need to design that bridge for 100-year and 500-year extreme event storm scour,” he said. “And in order to do that, we need to stick the piles further into the ground to get them sufficiently deep below.”
Crews also have been working with a restrictive right of way, creating constraints on the placement of equipment and materials. The team planned out the work to ensure no one was boxing equipment or people in.
“We've had to bring in some specialty equipment during the beam erection on the Okaloosa Island side to assist with that,” Lawrence said.
That includes a telescopic crawler crane for setting girders on Okaloosa Island. Superior also used two 1300 series Liebherr cranes on the project.
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Due to the sound’s shallow water near the construction site, the team built temporary work trestles on both shorelines of the bridge to access the waterway construction.
“There was not enough water depth to navigate a barge for the construction, so the trestle was necessary for the project,” Durshimer said.
The first use of wax post-tensioning in Florida also presented some challenges or learning opportunities. WSP had to design the bridge differently, using heavier girders and a wider girder web, Durshimer said, calling it an unbonded post-tensioning design.
“There’s a lot of cool stuff happening on the project, but I would say the highlight is that post-tension splice girder that utilizes flexible filler,” Durshimer added.
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Traditionally, contractors in Florida used grout to fill in that space, but that grout created maintenance challenges for FDOT, according to Durshimer.
“There were instances where there was poor grout or soft grout that allowed moisture and chlorides to infiltrate the tendon duct, which caused the steel in the post tensioning strand to corrode, which brought into concern the integrity of the structure,” he said.
The flexible filler material, or wax, provides several advantages for FDOT.
“The wax will completely fill the duct, and it'll provide some corrosion protection for it,” Durshimer said. “It'll prevent air, moisture, and chlorides from getting inside of that duct.”
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FDOT will be able to access and maintain the post-tensioning system, including removing that tendon and replacing it without removing vehicle traffic on the bridge.
“It provides a drastic improvement to the maintainability of the structure,” Durshimer explained.
Durshimer said he takes pride in engineering the first wax post-tension splice girders in Florida.
“With FDOT releasing their new specifications for wax, we wanted to rise to the occasion here, and we had a partner with Superior that was on board with it,” Durshimer said. “So very, very happy with the engineering that we've done on that.”
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Lawrence added that he is excited about the project’s impacts on the community and the positive feedback the company has already received. Superior has hired several local workers.
“What we're building out here is going to really improve the community,” Lawrence said. “Employing people, being a part of the community, all that is something that we're proud of at Superior.”
- Owner: Florida Department of Transportation
- General Contractor: Superior Construction, Fort Walton Beach, Florida
- Designer: WSP, Tampa, Florida
- Construction Engineering and Inspection: Eisman & Russo, Jacksonville, Florida Photos courtesy of Superior Construction
