Maintaining operational tempo

posted on 6th April 2018

Keeping flights to schedule is no easy task and takes a huge amount of work on the part of so many links in the aviation chain. One of those links is the team that ensures runways and taxiways are fit for purpose and, above all, completely safe for the large numbers of take-offs and landings they handle each and every day

With six runways as well as taxiways and a huge amount of apron space to continuously maintain, even in the teeth of the harsh Colorado winter, ongoing runway maintenance is a big challenge at Denver International Airport (known as DEN). Five of those runways are 12,000 feet (3,600 metres) in length and 150 feet (46 metres) wide; the other, at 16,000 feet long (4,800 metres) long and 200 feet (61 metres) wide, is the longest commercial runway in North America. The airport operator has at least one crew responsible for work on its runways every single shift.

“Normally, our crews consist of one operations supervisor, one crew supervisor and 11 operators,” explains Mark Baker, senior director of airport infrastructure management at Denver International Airport. “All of our maintenance personnel are trained on the work required for every runway,” he continues – including spall repairs (spalling is the breaking up for the surface), erosion control, rubber removal, painting/striping and foreign object debris (FOD) clean-up.

Runways are inspected twice a day by DEN’s airport operations managers as per Federal Aviation Administration (FAA) Part 139 airport certification requirements. Additionally, DEN follows the FAA requirement to have its airfield pavements inspected and evaluated every three years as part of its pavement maintenance programme. “Based on this evaluation, rehabilitation projects are developed that do everything from full panel replacements to spall repairs,” Baker notes. “A recent example of a project like this was the 17L/35R Runway and Taxiway Rehabilitation project, which cost approximately US$36 million.”

Work fits around the airport’s busy operational schedule as best as possible. During daytime hours, DEN will sometimes close a runway complex for a maximum of 2 to 3 hours to allow for any urgent repairs. However, the majority of runway work is undertaken during slow traffic periods at night, usually between 23.00 and 05.00 to avoid interrupting air traffic.

By way of contrast, Scotland’s Glasgow Airport has just the one runway – it is nearly 8,750 feet (2,665 metres) in length. Its maintenance is the responsibility of a dedicated civil engineering team who are available 24/7, 365 days a year. The team carries out minor maintenance works and any emergency repairs that are required on the runway and taxiways, as well as maintaining the airfield paint markings. Glasgow Airport also has a team of high voltage specialists who are responsible for undertaking controlled isolation operations. This allows the gateway’s operator to safely undertake repairs of the lighting systems on its runway and taxiways.

Maintenance of all of the airport’s paved areas falls within its dedicated asset replacement management system. In practical terms, explains Glasgow Airport operations director Mark Johnston, that means refurbishments are carried out as when they are required, or when the surface reaches the end of its lifespan. The gateway’s airside and infrastructure teams routinely monitor the airport’s paved areas and undertake preventative maintenance work, and the airport schedules two runway night closure periods a year for 10 nights at a time in which it carries out repairs that do not fall within usual asset replacement procedures.

SPECIALISED EQUIPMENT

A wide range of equipment is required to maintain a safe and efficient runway, Johnston observes – that includes compactors, pneumatic drills, hot boxes, bitumen boilers, pavers, concrete mixers and flexible concrete boilers. Friction measurement is one of the core tasks for Glasgow’s Airside Operations department and tests are carried out monthly to monitor surface condition that require the appropriate specialised equipment. A more thorough and comprehensive assessment is undertaken annually.

For the majority of Denver International’s work on its runways, the operating authority utilises a range of spall repair equipment, paint trucks, sweepers and runway brooms, loaders/skid steers and haul trucks, Baker remarks.

DEN’s operations departments employ Dynatest continuous friction measuring equipment (CFME) to test the runway surfaces for friction. Like any airport of size that faces harsh winters involving snow and ice, it also has a collection of specialised multi-function snow equipment that is used during the winter months for snow-clearing operations.

Friction testing is also conducted routinely during the winter months as part of the snow removal process, Baker continues. In the summertime, DEN runs the CFME on each runway every six weeks to check for the unwanted build-up of rubber deposited by aircraft tyres.

Due to the very cold temperatures that can be experienced in Denver in the winter, less nighttime work is undertaken then on the airport’s runways; however, work does continue during daylight hours. For that reason, DEN tries to complete as much runway maintenance and repair work as it can during its warmer seasons.

However, Glasgow’s Johnston informs: “Where possible, we plan to carry out most of our repairs during the winter period, when airline schedules are at their quietest and we have more time to undertake maintenance. Our key priority is to ensure that any maintenance work we undertake has a minimal impact on the airport operation.”

CAPITAL IMPROVEMENT

Longer term capital improvements also have to be factored into workflows. “We are currently looking at options for a full runway rehabilitation or partial resurfacing project as part of our asset replacement plan,” says Johnston. “This is likely to include some strengthening work on the runway and also surface replacement to improve drainage characteristics and friction levels.

“Our runway resurfacing project will cost in the region of £15 million (US$21.5 million) and will take approximately five months to complete. The vast majority of the work will be undertaken at night and operations will run as normal during the day.

“Our primary aim is to ensure business as usual. We will use external contractors to deliver this project, although the overall coordination and operational delivery will be undertaken by Glasgow Airport teams,” Johnston adds.

Normal maintenance of Denver’s six runways is an ongoing process of course. But, Baker notes, larger capital improvement plan (CIP) improvements require additional justification and approvals, and are generally worked in concert with the FAA’s Airport Improvement Program.