Ft. Lauderdale Int'l Buys Time for Future Runway Project

Robert Nordstrom
Published in: 

Ft. Lauderdale-Hollywood International Airport (FLL) has a massive runway project coming up in the next few years. In 2012, its current 5,276-foot general aviation runway will be removed and rebuilt as an 8,000-foot commercial runway to open in September 2014. The project will include a bridge to carry the runway and parallel taxiway over railroad tracks and a highway.

In the meantime, however, the existing runway, 9R-27L, needs to remain open to traffic. A $635,000 rehabilitation project completed last June is making that possible.

FLL airport engineer Gasser Douge believes that the original pavements on 9R-27L were put down in the 1960s and sectional rehabilitation was performed throughout the '70s and '80s. Foreign object damage(FOD) issues led to the application of a rejuvenator coating in 2005.

"The runway exhibited severe weathering and raveling," Douge recalls. "The rejuvenator gave us three years, which was the intended solution at that time, before we started having FOD problems again."

At that point, FLL commissioned engineering consultant Tetra Tech to provide options for extending the life of the runway until the new runway is complete.

Evaluating Options

Facts & Figures

Project: Runway Rehabilitation

Location: Fort Lauderdale-Hollywood International Airport

Cost: $635,000 (including restriping)

Engineers of Record: Tetra Tech

Consulting Engineers: CRJ & Associates

Products: Grip-Flex Type B Micro-Surfacing, Grip-Flex Thermoplastic Resin Coating

Contractor: Ameriseal of Ohio

With assistance from consulting engineers CRJ & Associates, Tetra Tech presented FLL with three possible solutions in September 2008.

Option one was to perform a mill and overlay resurfacing, which would extend the runway's life more than four years. The second option, which would extend service for two to four years, called for application of Grip-Flex, a thermoplastic coal-tar emulsion slurry seal. Option three was application of a conventional emulsified asphalt slurry seal, which would extend life for less than two years.

With work on the new runway scheduled to begin in about three years, the Grip-Flex option fit the airport's schedule. It was also less expensive than a mill and overlay project. And a slurry seal was deemed inadequate for treating the runway's raveling problem.

Mark Wolfe, engineer of record for CRJ & Associates at the time, describes the Grip-Flex choice as a happy medium.

"The runway had a severe raveling problem," recalls Wolfe, now senior project manager at T.Y. Lin International. "It was a big concern for the private jets using the runway and a major headache for airport operations and maintenance. The mill and overlay was too expensive, and the slurry seal wasn't good enough. Grip-Flex competed well, so that's what we went with."

The airport didn't want to spend a lot of money on a runway that was going to be replaced in a few years, Douge explains.

Due Consideration

Cracking (left) and ravelling (right) were issues before FLL's runway rehab project in 2009. 

Actually, the airport had been evaluating Grip-Flex as a possible solution to its short-term needs for a few years. In 2006, Ameriseal of Ohio applied several test patches on the runway. After two years, Grip-Flex's surface remained a vivid black and was wearing well, recalls Douge.

The test patches also maintained a skid-resistant landing surface and exhibited water-shedding capabilities comparable to the existing grooved surface, which negated one of the main concerns regarding the product.

"We learned that the product's micro-surfacing has enough irregularities to prevent the formation of a film that would promote hydroplaning," Douge explains. "We took care to clarify these issues with the FAA."

Confident in its evaluations, the airport began the project in June 2009. Ameriseal staged materials and equipment on an adjacent runway, then shut down Runway 9R-27L to apply the product. The project was completed in less than a month.

To decrease costs, the airport chose to resurface the heavily trafficked 50-foot center section of the runway with Grip-Flex Type B Micro-Surface and to spray Grip-Flex Thermoplastic Resin, a slurry coating, on the 25-foot outer edges of the runway that encounter less traffic and wear.

"You don't need the same kind of friction on the outer edges of the runway as you do on the runway keel," Douge explains.

The Type B aggregate is also smaller and less abrasive to aircraft tires, adds Wolfe.

Test Results

Once complete, the Florida Department of Transportation conducted tests using continuous friction measuring equipment to ensure that the resurfaced runway met FAA standards.

Test results indicated that Grip-Flex increased the friction coefficient of the grooved asphalt surfaces by as much as 37% in critical areas where the existing grooves had deteriorated - despite the fact that the product partially filled the grooves. Post-application test results revealed an average friction value (mu) of 0.8, which is well within FAA standards.

After a year in service, Wolfe reports that Grip-Flex appears to be providing a stable surface with no raveling, and its black finish still accentuates the white pavement markings. Overall, he's confident the surface will hold up until the runway is closed for demolition in 2012.

"Everyone seems pleased with the results of this project, including Broward County Aviation Department and the FAA," says Jonathan Moore, aviation business manager for Ameriseal. "We had to prove we could perform to their standards. When you are able to exceed those expectations, everyone wins."

Douge agrees that the project ran smoothly and has been a success.

"We had no issues," he summarizes. "We coordinated closely with airport operations, meeting weekly to discuss progress. We kept an inspector out on the airfield on a full-time basis to monitor the project. The friction test was well within the intended range. We are very pleased with the results."


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