How do you determine when your crew is ready to do its own bridge replacement? Well, a nudge from the state helps.
Cape Coral, Fla., is overrun with bridges. Two-lane, four-lane, six-lane, short span, multiple pier, concrete slab, corrugated metal arch and pedestrian, they traverse 431 miles of marshy canals fed by storm and outfall pipes. Most carry traffic. Over half are navigable.
Of 158 bridges in the municipal area, 121 fall under county or state responsibility when it comes to inspections. Chris Camp, public works maintenance director for the city, knows that the ones under 20 feet are up to his department to inspect.
“We thought this one made that, but it turns out we could have the state come and do it after all. So we went through the paperwork to add it to the state’s bridge system,” he said.
Unexpectedly, the steel pipes in the Overhold Canal bridge turned up a number of gauges and tears. While it’s possible they were incurred at the time of installation, they had expanded and deteriorated over time and now earned the structure an overall rating of just 47: not “failing,” but “poor.” Anything below a score of 63, Camp noted, is worrisome.
The average age of Cape Coral’s bridges is 40–50 years old. Many were built between 1961 and 1981, soon after the city was founded.
“We’re pretty good with preventive maintenance,” said Camp. “We can repaint, fix spall, set cracks and jaunts and all that.” The ravages of time are advancing quickly, however, and more of those bridges are requiring corrective repairs.
“When it’s done they send us a detailed report with a list of any issues and repair recommendations,” Camp said of the state inspection. “We took a look at it and decided we could pretty much handle the suggestions they made for repair with our existing pipe crews.” Part of the reasoning was that the specific location of the Overhold Canal was ideal for a first attempt at this type of project.
“For one thing, the location was not in a really populated area, so it helped that we could block off the road. And we could keep the stem walls.” There were no buried phone lines or utilities in the remote area, and the department already owned a large-reach excavator.
With detour routes available and newly paved roads at both intersections framing the canal lane, 100 percent of local traffic could be detoured for the duration of the project.
Camp and department and city officials looked at several methods of repair, including contracting to slip-line the pipe, but were taken aback by the price tag. “And it’s still a Band-Aid when you’re looking at that much damage,” he said.
After determining a methodology, crew members devised their own sequence. They knew they had the option to work longer days at the location without disrupting traffic, but they would also have to enlist pumps to dewater the canal. They decided to drop all four of the 60-foot, high-density polyethylene pipes in from overhead.
In addition to the stem walls, the guardrails were also in good enough shape to keep. Each section of pipe was then laid in on layers of dirt and stone and mudded for stability. The entire project took about six weeks to complete.
“The only thing we subbed out was the paving,” Camp said. The work was done for under $50,000, a little more than half the price of sliplining.
“The pipes we chose are good for a hundred years or more, knock on wood, and we got a newly paved road out of the deal. We definitely got a lot out of the experience, and who knows if we’ll have to apply it again,” Camp noted. “We’ll definitely be looking at that as a possibility.”