Project Runway: Testing How Tarmac Handles Jet-Plane Traffic

Runways are not like highways. Instead of supporting mere 80,000-pound big rigs zooming by at 70 mph, landing strips must handle 1.2 million-pound planes taxiing at a pavement-stressing crawl. (Jets are going too fast during landing to do any real damage.) To ensure tarmacs can take the abuse, the Federal Aviation Administration maintains the National Airport Pavement Test Facility near Atlantic City, New Jersey.

Soon the FAA will be investigating the effects of a vexing new trend: huge cargo jets with 10-wheeled landing gear, like Russia's Antonov AN-124, that haul stuff like oil field pumps and locomotives. Just setting up the tests is a supersize endeavor. Before laying new pavement, engineers must rework the ground underneath—there's a big difference between, say, clay and sand. Then they layer on 50 inches of concrete or asphalt laced with up to 1,000 sensors. Finally, it's time to rev up the test vehicle (shown above), which runs on rails and uses hydraulics to apply downward force of up to 75,000 pounds—per wheel.

If trials show that the big birds damage runways, airports like Houston's George Bush Intercontinental—which sees at least one Antonov a month—will have a tough decision: Rebuild the runways or tell oil companies to land elsewhere. Now that's pressure.