Making the Case for Diamond-Grooved Surfaces

Effective Solution at FLL

At the Fort Lauderdale Hollywood International Airport (FLL), the asphalt-paved Runway 9L/27R was experiencing  distress and lost friction. The Broward County Aviation Department decided to form a plan to rehabilitate its runway.

According to Gasser Douge, airport engineer for the department, a loss of up to 40 percent of the transverse grooves triggered an investigation into the pavement condition, with concern centering on the pavement’s loss of friction. The design engineer recommended grinding and grooving as the solution to the problem.

The scope of work included patching areas of deteriorated pavement, diamond grinding approximately 110,000 square yards of asphalt runway deep enough to remove the existing grooves, then re-grooving the runway in accordance with standard FAA specifications, and finally re-striping. During the project, high levels of production were required and maintained by the crews during short work windows, seven nights per week. An added challenge was the inconvenience caused by having to evacuate the runway intersection when planes were arriving.

Diamond grinding a major runway is a first for Broward County and possibly for the entire region. The technique is a viable and cost-effective method for rehabilitating asphalt-paved runways and highways. While the total project cost was $1.5 million, the diamond grinding and grooving cost was only $500,000, or $5 per square yard. The cost savings were substantial when compared to an alternate repair method such as milling and filling. The project was completed in August, 2010, leaving the facility with a like-new surface and the friction necessary to ensure the continued safety that modern day airports require.

Results at Dyess Air Force Base

Located outside of Abilene, TX, the Dyess Air Force Base is home to the 7^th Bomb Wing and 317^th Airlift Group. Years of wear and rubber deposits from landings by B1-B Lancer bombers and the C-130 Hercules aircraft had made the runways significantly polished due to the lack of texture.

An aggressive two week runway closure window was negotiated with the Air Force to complete the grinding and grooving of the 125,000-square yard main concrete runway as well as the 25,000-square yard asphalt auxiliary runway.

“Grinding and grooving definitely helps reduce the potential for hydroplaning on a wet runway,” says Barry Mines, Chief of CE Technical Support for the Dyess Air Force Base. “The grinding helps provide a “rougher” surface for better traction (frictional resistance) and the grooving provides channels for the water to run laterally off the runway. If you get the water off of the runway, you reduce your hydroplaning potential.”

Grooving was chosen since it is a surface treatment recommended by the Air Force. “… Our Unified Facilities Criteria (UFC) 3-260-2 titled “Pavement Design for Airfields” requires that new, reconstructed, or resurfaced runways must be grooved,” says Mines.

The production settled into a relentless pattern with two 12-hour shifts working around the clock. Six water trucks were in use nearly full time, cooling down the diamond blades. The job was completed on December 23^rd, six days ahead of schedule and came in within budget and without accident or injury.

The Air Force continues to employee this technique on additional runways at Dyess Air Force Base. “We are currently completing the resurfacing of a 3,500-foot-long landing zone which is being grooved,” says Mines.

FAA Recommendations 

A transverse grooved saw-cut surface provides impressive braking and generates a side force that can prevent lateral drift. Pilots find that deceleration on a wet, saw-cut grooved surface is almost the same as on the dry surface, and any nosewheel steering lost on the ungrooved surface returns as soon as braking resumes on the grooved surface.