As a passenger on a plane, you can feel that moment when it lands, when the tyres touch the runway and the plane brakes to a stop.
For maintenance workers at Changi Airport, that moment is measured in tyre rubber that gets deposited on the pavement.
Every month during overnight runway closures, a team of workers scrapes the rubber off the two runways and repaints the landing zones with a special paint, which is treated to have more friction.
The New Paper followed the team on one of its recent monthly maintenance jobs, which runs from about midnight to 6am.
The team also ensures that the grass surrounding the runways is cut, the airside is cleaned, the airfield lighting is adequate and that runways and taxiways are free from foreign object debris and defects such as potholes.
It is all part of the behind-the-scenes work that keeps Changi Airport at the top of the airport listings. Changi was voted the world's best airport last year, the fourth time it has clinched the top prize since 2010.
The airport handles more than 50 million passengers each year and 6,500 flights come in every week.
The airfield lighting team and civil engineering team from the engineering and development group are the two teams responsible for runway maintenance.
Mr Andy Chin Yong Hwee, 33, airfield lighting system manager, said that as air traffic continues to grow in the Asia-Pacific region, there is a need to strike a time balance between flight operations and runway maintenance.
And this is quite challenging.
He said: "(This) ultimately affects the safety of aircraft landings and take-offs."
The runways have daily inspections throughout the day and night. Sweeping is carried out at the touchdown areas during the daily 15-minute runway closures.
And at night, the two runways will each close for about 90 minutes for three Runway Sweepers to go up and down the 4km runways - at 25kmh - to look for debris.
The vehicles are equipped with laser-guided sensors, which can detect debris the size of a golf ball.
Airfield lights are checked and defective ones replaced.
The lights are designed with thorns, so that birds do not perch and dull the lights with their poop.
Mr Low Kwee Hong Clarence, 34, civil engineering senior manager, said that objects found on the runway may pose a danger to flight operations. This includes loose pebbles and stones.
He said: "With some 600 hectares of turf, the presence of water bodies and its proximity to wooded areas and the coast, wildlife such as birds, lizards, tortoises and snakes can sometimes be found on the runway too."
FIVE THINGS ABOUT RUNWAY MAINTENANCE AT CHANGI AIRPORT
1. There are 11 Changi Airport Group engineering & development group staff members on night duty.
2. There are about 50 maintenance staff (for night runway closures).
3. There are eight vehicles, including one Surface Friction Tester, four Runway Sweepers and three Inspection Rovers.
4. The Daily Runway Closures (Night) occur once a day, per runway, with each closure lasting for about 90 minutes.
5. Each closure for the Monthly Runway Closures (Night) lasts for about six hours. Major works including painting, road resurfacing, removal of aircraft tyre rubber deposits, servicing of airfield lighting are done.
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