TUESDAY, FEBRUARY 13, 2024
Officials in Florida recently announced that construction of the replacement John T. Brooks Bridge between Fort Walton Beach and Okaloosa Island has begun, marking a first in the United States for a corrosion-resistant post-tensioning method that aims to aid the surrounding environment.
According to Equipment World, the Florida Department of Transportation chose the design-build team of Superior Construction and engineering firm WSP to demolish and replace the bridge with a wider, longer, taller, six-lane structure.
Project Details
The report states that the bridge was built in 1965 and currently handles around 66,000 vehicles daily on its four-lane U.S. 98 span over the Santa Rosa Sound and Intracoastal Waterway.
The current bridge is reportedly too low for larger boats to pass under. In 2013, a barge hit the bridge, which also carries utilities to Okaloosa, knocking out water service to the island.
The $171 million project will also reportedly add biking and walking paths, drainage improvements, intersection upgrades and special lighting to help efforts to protect sea turtles.
“It's not just going to be a bridge,” said Matt Durshimer, WSP project design manager. “There are things that will make this an iconic structure unique to Fort Walton Beach and Okaloosa Island. There are things you won't see on other bridges in the state or in the country.”
When finished, the new bridge is expected to be the nation's first internal-tendon spliced-girder bridge to use unbonded flexible filler, according to WSP.
That means that instead of using grout to cement in the post-tensioning tendons, which can over time be susceptible to corrosion, inspection and maintenance problems, the ducts that hold the tendons would be filled with wax to protect the strands from corrosion.
The report explained that the wax is melted and injected into the duct.
“The key thing is, now instead of having a void in the duct that was filled with grout, which provides structural performance, that duct is now filled with wax, and so it's hollow,” explained Durshimer. “So it changes the performance of that girder, because of what was previously solid concrete is now a hole on the girder.”
Durshimer added that the method is used frequently in Europe, and FDOT has researched it thoroughly, using it in projects due to its corrosion-resistance in the state’s salty climate.
“The mechanism of instead of using grout and now using wax specific to a post-tensioned splice girder bridge is what is, to the best of our knowledge, the first in the United States,” he stated.
The bridge design reportedly also accounts for the hollow ducts, with a thicker web for the beams, from 8 inches to 9 inches thick.
“It still meets absolutely every design code, and every load rating requirement of the structure is achieved,” Durshimer stated. “We're not sacrificing anything by doing that … It's a pretty well-engineered, well-understood mechanism of how to transfer the stresses.”
Evan Lawrence, Superior Construction division manager, added that the contractor used the wax on previous projects, though this time will be its first for this type of bridge. Additionally, a specialty subcontractor has reportedly been hired for the work.
Superior reportedly plans to use a trestle system for workers and equipment instead of barges, as barges had come loose during Hurricane Sally in 2020 and damaged parts of the Pensacola Bay Bridge that had recently opened or were under construction,
“We've designed the trestle with steel beams, steel pipe pile,” Lawrence said. “It's a very modular system that it is easy to take in and out as needed or switch around.” He added that there’s nothing to come loose, and that the company currently has a hurricane plan.
“As soon as we know there's a storm coming through the Gulf, we start evaluating the sites, determining what needs to come off the trestle,” he said.
The bridge’s construction is expected to take place over three phases, while the old bridge will remain open to traffic until the first two phases complete the westbound bridge. Traffic will then reportedly move to the new bridge, while the old one will be demolished. The third phase will build the eastbound bridge.
A release from FDOT states that the project is expected to be completed by August 2027. The 2,111-foot bridge will reportedly be 793 feet longer than the current one.
To meet that deadline, Superior stated that it plans to construct each end of the bridge at the same time, with two crews working toward the middle and then back to the ends. The new eastbound bridge will reportedly be built over the existing bridge’s footprint.
Blasting and full demolition is reportedly not planned. Since the new foundation is wider and longer than the current one, the report states that the existing foundations can be cut off at the mud line.
According to officials, the most challenging part will be the first phase, as teams work within the narrow right of way, which is about the same width as the cranes’ tracks.
“As we develop our beam-placement plan, it's a lot of steps along the way to make sure we don't block ourselves in with one of the cranes,” Lawrence stated. “Because at some point, we have to pull these cranes off site, or they will just be stuck between the piers.
“It's very tight, it's very challenging, working near businesses and working around the existing structures.”
According to the report, both Lawrence and Durshimer expect the bridge to be a boon to the community, helping to alleviate traffic and make conditions safer for Okaloosa Island residents who rely on the bridge for their utilities as well as hurricane evacuations.
“This job really helps connect the community between Fort Walton Beach and Okaloosa Island,” Lawrence said. “This is going to be iconic for the area with the pedestrian improvements, the access, how people perceive this project. I'm glad to be a part of that.”
Along with the new spans, highlights of the project include:
“This is is shaping up to be an opportunity for a landmark project, a capstone project for what design-build can bring to both the owners, to the community as a whole—the amount of stakeholder coordination done with state and federal agencies to meet all their expectations for the project,” says Durshimer.
“This job has it all ... In terms of embodying civil engineering and civil construction into one, this project has it,” he added.
Environmental Concerns
The report added that any bridge construction project in Florida’s environmentally sensitive waterways and marshes face stringent requirements.
As such, the Brooks Bridge replacement project reportedly goes further than just those requirements by adding special lighting to protect the area’s sea turtles, whose nesting and hatching habits can be disrupted by artificial light.
The bridge’s lighting near the shoreline will reportedly be low intensity with an amber hue to not hinder turtles coming up to lay their eggs or hatchlings heading to the water, Durshimer stated.
The light poles will also reportedly be spaced closer together to light the road but not emit sky glow that could disorient the turtles. Lights farther away from the shoreline are also expected to be designed to reduce sky glow, being pointed downward to prevent light from spilling above the fixture.
Tagged categories: Bridges; Bridges; Coating Application; Construction; Corrosion; Corrosion protection; Corrosion resistance; Department of Transportation (DOT); Environmental Controls; Environmental Protection; Government; Health & Safety; Infrastructure; Infrastructure; Jobs; Maintenance coating work; Maintenance programs; Ongoing projects; Program/Project Management; Roads/Highways
