In the broad scheme of a major airport runway expansion and rehabilitation project, setting the runway lights may seem like a minor job.
But, Jimmy Hipps of Edwards Airfield Services Inc., would disagree. Hipps, as a field supervisor, leads a crew trenching in lights at George Bush Intercontinental Airport in Houston. Just one portion of the job has involved $4 to $5 million in electrical work — 30,000 ft. (9,100 m) of cable and 1,700 lights.
It’s tough to decide what’s most challenging: ensuring each light is positioned as carefully as the Federal Aviation Administration (FAA) demands, or getting through brutal flint rock that lies beneath the asphalt runway base.
Hipps and his crew have found ways to accomplish both.
Working with primary contractor W.W. Webber Inc., Edwards Airfield Services has joined several other subcontractors on what will end up being a multi-year, multi-million-dollar project.
Bush Intercontinental Airport serves more than 40 million passengers per year, according to the Houston Airport System. That makes Bush the 11th busiest airport in the country based on total passenger enplanements, which forecasts indicate will double by the year 2017.
To handle the increased air traffic, major construction is afoot. Runways are being added, lengthened, widened and repaved; a new taxiway system will include four high-speed exit taxiways, two connecting taxiways, two parallel taxiways and access points for two future taxiways.
In addition to new runways and taxiways, the project includes a new electrical vault, an airfield grounds and maintenance facility, a maintenance building and access roadway system, perimeter security fencing, two taxiway bridges, electrical installations, and striping and painting.
Edwards Airfield Services is doing all the runway and taxiway light electrical work. Just what goes into setting lights on a project like this?
Hipps describes it in stages: first, a layer of asphalt — heavily compacted to just two-in. (5 cm) thick — is put down as the “bond breaker.” The asphalt acts as a buffer zone between the ground and the final layer of concrete, preventing damage that ground shifting could cause.
Next, Hipps’ crew trenches through the asphalt and 10 in. (25 cm) of flint rock. That part might not sound too difficult. “But, we change-out trencher teeth every 600 to 800 ft.,” Hipps said. “That’s some tough river rock.”
Hipps and his crew rented the Vermeer T855 rockwheel hydrostatic trencher when a smaller, competitive unit wouldn’t get the job done.
The T855 is designed specifically for operators in the rock-trenching market. It features oscillating tilt tracks that allow it to follow the ground’s contour, ensuring a vertical trench even on slopes up to 9.3 degrees.
This 96,000-lb., 335 hp (43,545 kg, 250 kW) trencher also features a high-performance rockwheel attachment equipped with 1-in. (5 cm) shank rotary carbide teeth and can dig up to 54 in. (137 cm) deep.
According to Edwards Airfield Services, it was able to rent the machine from the Vermeer Houston dealership for about 5 percent of what it would have cost them to purchase the machine, which was ideal since they didn’t anticipate needing it more than about a month. “It just made sense to rent,” Hipps said.
After the holes and trenches are cut, the crew installs the conduit, cans, cable and transformers. When the electrical groundwork is in place, an additional asphalt bond breaker is added.
Finally, a paving crew puts down 19 in. (48.3 cm) of concrete before the lights are installed. Hipps and his crew of 16 oversee it all.
Edwards Airfield Services has been working with Vermeer for about 12 years. It rented the Vermeer T755 track trencher in the past, and had good luck with it, said salesperson Jason Rush of the Vermeer Houston dealership. But this time, the flint rock made things different.
“They decided to rent the T855 rockwheel this time because of the tooth-wear factor,” Rush said. “We’re still replacing 200 of the strongest carbide teeth money can buy every day, but if they were using a trencher, we’d have to replace teeth about eight times a day because of the way the chain turns in the ground — and that can affect productivity.”
“Once we started using the T855, we got 10 to 12 feet per minute — and it even cut through old cans that were in place too,” Hipps said. “It went much faster than we thought.”
Certainly having the right equipment is critical, but in regard to specialization in runway lighting, Hipps said his company’s experience sets them apart.
“We don’t have much competition in this market,” he said. “There aren’t many contractors who can adhere to the strict FAA standards.”
Hipps referred to the fact that each light must be placed within .0625 of an inch as specified, a strict FAA regulation. He and his crew have had a lot of practice.
Hipps personally has been working with Edwards Airfield Services for about 15 years; another crewmember has been with the company 12 years. Hipps’ company has been on current runway expansion and rehabilitation jobs at Bush Intercontinental since 1997.
Previously, it performed installations at Dallas/Fort Worth, Love Field, Austin, Houston Hobby and other large Texas airports.
In comparison, Hipps described this portion of the Bush Intercontinental job as “major.”