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Chengdu Tianfu International Airport
Keeping Water Out of the Deep Base One Detail Hidden Beneath the Pavement
Supply
- Products supplied
- Runway Lighting Taxiway Lighting Sequenced Flashing Lighting System Precision Approach Path Indicators (PAPI)
- Quantity
- Nearly 25,396 sets of various AGL equipment
Behind 25,396 Sets of Equipment
Chengdu Tianfu International Airport is a 4F-class international airport. Three runways were added at first phase, and the airport opened for operations on June 27, 2021.
During construction, Tianfu took delivery of 25,396 sets of airfield lighting equipment from Airsafe, covering the approach, runway, taxiway and other areas. It was also the first airport in China to use LED PAPI and LED sequenced flashing lights.
On this project, one component that passengers will almost never see left a deep impression on everyone who built it: the L-868 load-bearing deep base.
It sits below the pavement.And the problem is about happened down there too.
If The Deep Base Gets Water In It, The Whole Circuit Will Be Affected
Airfield lights are inset into the pavement, each with a load-bearing deep base housing the individual light controller, the isolation transformer, and the primary cable.During construction, waterproofing of the deep base became a particular concern for the build team.
Once rain or damp gets into the base, the isolation transformer and primary cable can sit in moisture — or in standing water — for years. As water works its way into the insulation, circuit performance degrades and insulation resistance falls; it can also disrupt communication with the individual light controllers. All of it becomes a long-term risk to running and maintaining the airfield lighting system.
So waterproofing the base looks like a structural question. What it actually protects is the electrical equipment inside it — and the operating environment of the entire airfield lighting circuit.
Whether water can be kept out for the long haul is not a small matter.
Can the Water Inlet Be Sealed Off
With that as the goal, Airsafe’s engineering team and the construction headquarters studied the base together.
The Dual-seal Keeps the Water Out
The solution was a cover built as a dual waterproof structure. The first O-ring sits where the cover meets the base face to face; the second sits between the side of the cover and the inner wall of the base. One seals the face, the other seals the side, blocking the likely entry paths from two directions and forming a double barrier between cover and base.
The design is not complicated, but it answers a very specific problem on a working airport: how to keep water out of the base for years. The engineering changes that matter are rarely the most intricate ones; they are the ones that solve a real problem and hold up in service. The revised base seals so tightly that lifting the cover takes a deliberate pull against the vacuum inside — it has to be pried open with a special tool.
Five Years On: How The Dual-Seal Held Up
Whether a waterproof structure is any good can’t really be judged the day it is installed.
The real test comes years later.
Tianfu has now been in service for about five years. According to the airport, insulation resistance on the relevant airfield lighting circuits is still high. The redesign of the base has done what it was meant to do.
What You Cannot See Matters Just as Much
With an airfield lighting system, what people see is the row of lights along the runway and taxiway.But whether the system performs reliably over the long term depends on a great deal that is hidden below the pavement.
Does water get into the base?
Do the individual light controllers keep working?
Does the isolation transformer stay in a good operating environment?
Does circuit insulation hold up?
None of these are visible day to day, and all of them bear on the reliability of the whole system.
The improved deep base at Tianfu is not a complicated technical concept.
It is a redesigned cover for a real engineering problem, with two seals — one on the face, one on the side — to keep water out of the base as far as possible.
Yet that is exactly where engineering value tends to live: in details nobody sees.
Keeping water out of the base protects more than the equipment inside it.