Japan using physical tests to build runway at Iwakuni


MARINE CORPS AIR STATION IWAKUNI, Japan — The government of Japan didn’t want to rely on models and computer simulations to decide the finishing touches for its $2.4 billion runway reconstruction project at Iwakuni.

So it’s working with the real deal.

“The government of Japan is doing an actual physical test,” said Mark Nedzbala, the Army Corps of Engineers resident engineer at Iwakuni.

“Engineering is typically done more with modeling and computer analysis. [Real-life testing] is not typical from an American perspective.”

But the results will be very accurate and could be used to guide future projects in Japan, he said.

Japan is using the physical tests — which cost about $10 million — to come up with a runway design as the land-reclamation part of the project is in its third of three phases.

Reclamation work is fairly common in land-scarce Asia. The airport in Kansai is built on reclaimed land — and it’s sinking. Engineers know some settling and earthquakes are to be expected.

Instead, the tests are looking at how various runway construction methods will respond to movement and impact.

“There’s an awful lot to the runway besides what’s below it,” Nedzbala said.

One factor being examined is whether the runway should use reinforced concrete, which is strong but difficult to repair, he said.

For the largest test, eight concrete lanes made from different materials were laid atop a massive elevated platform on part of the previously reclaimed area. Engineers use water-filled bladders to lift the structure. A series of steel shims then are removed to simulate varying levels of settling. After the shims are removed, the impact on the concrete above is measured.

The eight lanes will help test a variety of factors, Nedzbala said.

A second test involves an 85-ton vehicle with airplane wheels stomping on the sample runway to simulate the force of repeated aircraft landings.

The tests are full-scale — the samples are the exact thickness and construction of a real runway, so there’s no modeling.

Once the tests are complete, the testers — including some professors from Hiroshima — will issue a report with their findings, expected in October.

“At that point they can finish the design,” Nedzbala said. “We’re getting close.”

Runway fast facts

The new runway will be the same size as the current runway — 8,000 feet with a 1,000-foot overrun. The current runway is 5 feet above sea level; the new one will be 10 feet above.

The final project is expected to be completed in 2009. It will be capable of supporting Iwakuni’s current aircraft, heavy-lift cargo planes and Navy planes from Carrier Air Wing 5, which is relocating to Iwakuni from Naval Air Facility Atsugi.

— Juliana Gittler

Fill from a nearby mountain is sent by conveyor belt to the water. Barges then carry it to this floating reclamation barge, which scoops up the roughly 350,000 cubic feet of fill transported daily and pours in into the reclamation areas.