The scale of the airfield ground lighting (AGL) infrastructure at the world’s big airports is huge. It all has to be maintained, and upgraded as funds allow. The example of two large US airport hubs puts the nature and size of the challenges of lighting runways, taxiways, stands and all other areas of the airside environment into perspective.
O’Hare International Airport encompasses over 7,200 acres of land just west of Chicago, and has no less than eight active runways and associated taxiways; an additional runway is also currently under construction.
There are more than 15,000 runway and taxiway in-pavement/elevated light fixtures and more than 2,000 guidance signs on the airport. All elevated taxiway, in-pavement high-speed centreline, in-pavement guard and elevated runway guard lights, plus touchdown zone light fixtures are served by modern LED lighting with heaters.
Currently, O’Hare’s runway elevated edge lights are of the older halogen variety, but these will eventually be converted to LED once approved for use at O’Hare by the Federal Aviation Administration (FAA), a spokesperson for the Chicago Department of Aviation (CDA) – operator of the airport – confirms. Its light fixtures were, in the main, manufactured by ADB (now ADB Safegate), and most of the airport’s guidance signs are of Lumacurve manufacture.
O’Hare’s airfield lighting system has changed over time due to new technologies becoming available, especially with respect to the move to LED. “We also look for signs and lights that will hold up through difficult weather conditions in order to ensure that Chicago maintains the air operations area completely safe for daily operations,” the spokesperson notes.
Indeed, the biggest maintenance challenge facing Chicago O’Hare in regard to its airside infrastructure relates to the winter weather it experiences, CDA explains. Ice can be damaging to electrical circuits and in-pavement fixtures, while electrical grounds can result from glycol. Lights are also occasionally knocked down by vehicles and snow-removal equipment, while signs can be blown down by aircraft jet blast.
To meet the challenges, O’Hare’s airfield maintenance team is performed by a well-trained staff of airfield-certified electricians that, CDA says, “take pride and ownership of the air operations area”.
O’Hare replaces about 20-25 airfield lights each week, many of these having been knocked down by vehicles during snow removal operations in the winter time. The lights are replaced as soon as maintenance personnel have access to the area, this varying with the time of day and level of operations at the airport.
The move to LED has undoubtedly improved efficiencies and reduced maintenance costs at O’Hare, the airport operator considers. “These were low-hanging fruit for the CDA to incorporate through regular maintenance,” it points out. “ The challenge now is to upgrade the airfield electrical vaults to take full advantage of LED reduced wattage.
“The CDA is in the process of replacing older and inefficient circuit regulators with programmable, smart CCRs (constant current regulators) in order to take full advantage of LED and substantially reduce energy consumption and associated costs,” it confirms.
LED CONVERSION AT DENVER
Denver International Airport (known as DEN) has approximately 22,200 lights on the airfield. Originally, its airfield lighting had quartz fixtures but, confirms Kimberly Watanabe, DEN’s airside engineering supervisor: “We have been working on converting these over to LED fixtures. There are now four of the six runways with LED centreline and touch down zone lights.”
Additionally: “Most of the taxiway centreline lights have been converted to LED fixtures, though not on our gate and cargo aprons, but we have a project this spring to convert the gate apron taxiway centreline lights to LED.”
In fact, about half of the airfield is now lit by LED, Watanabe explains, most of it ADB equipment.
Preventative maintenance for DEN’s airfield lighting is performed during both the day and the night. The day shift is focusing on changing the quartz system to the new LED systems on taxiways, while the night shift works on re-lamping the quartz systems as needed. The quartz lamps are replaced in the field for elevated lights, but the in-pavement lights need to be refurbished in the shop, Watanabe informs. Quartz lamps are typically replaced within a year but flashing lights have a shorter life span. “We have been using in-pavement LED lights for five years now and very few have had to be replaced.” Indeed, DEN has focused on switching over to a LED system primarily for the maintenance benefits associated with the new LED lamps, Watanabe remarks.
Looking to the future composition of DEN’s airfield lighting system, the airport operator has undertaken an airfield lighting evaluation programme over this past year. This evaluation process allows for prioritisation of associated capital improvement projects. “We have plans to continue the evaluation process by looking into circuit load calculations for the system, modifications to the Airfield Lighting Control Monitoring System and considering energy-saving strategies,” says Watanabe.
Alongside the ongoing assessment programmme, DEN will continue its efforts to replace its quartz AGL system with LED in concourse taxiways and runway complexes through capital improvement projects benefiting from FAA AIP (Federal Aviation Administration Airport Improvement Programme) grants. “This work has primarily focused on in-pavement centreline lights and we’re also starting to include in-pavement hold bar lights,” Watanabe points out.
However: “We have not replaced elevated edge lights. One reason is the cargo pilots still use the infrared signature from the quartz edge lights on the runway to assist in landing operations during inclement weather.”
“One of the lessons we have learned since converting to LED is that we switched from a 3 step to 5 step Constant Current Regulator (CCR) to allow for the brightness between LED and quartz lights,” says Watanabe. “We had received feedback from the pilots about the vast difference in brightness when they would taxi between the two systems. The 5 step CCRs allows us to have more control of the brightness of LED system to match the quartz system.”
Finally, DEN has also built up an asset management team. This team keeps records of improvements made to airfield infrastructure, along with maintenance records. Several software programs are used to keep this information accurate and accessible to users. “This task is a great investment for DEN’s future,” Watanabe concludes.