Airports and Cities: Can They Coexist?

• Author: Ayres, Ed
• Position: Jim Starry, research - Statistical Data Included

As high-speed global commerce expands, and demand for air transport explodes, airports and cities are invading each-other's space in increasingly hazardous ways. The conventional response is simply to keep expanding airport capacity. But more imaginative solutions are now needed.

"SOME PEOPLE THINK THE WORLD IS FLAT," says the voice on the phone--a voice I have listened to many times in the past year.

At first I hear this as a comment on myopic worldviews, but then I realize it's not just a figure of speech. The man I'm listening to, Jim Starry, is being droll. He really is talking about geometry. But he's not referring to sailors who once worried that their ships might sail off the world's edge. He's ruminating about the people who build airports. Their runways are flat, and to Starry, a Colorado-based ecological designer, this doesn't make sense. A flat runway forces the 425-ton jet that is landing on it to throw its engines into reverse and burn a huge amount of fuel to come to a stop, he says. Imagine, instead, a landing strip that is slightly inclined--so that as the plane touches down it decelerates by rolling up a 2- to 3-percent grade.

Imagine that the plane, too, has been given a couple of key design changes. First, just before touchdown, a set of electric motors begins pre-rotating the wheels so that when the plane lands it won't encounter the huge, rubber-pulverizing friction that occurs when a motionless wheel hits pavement at 130 miles per hour. Then, as wing lift is transformed to wheel load, these electric motors begin functioning as generators, using the forward momentum of the plane the way a hydroelectric plant uses a river current. By tapping the energy of the plane's momentum, they slow the plane-without any further reliance on fuel to produce reverse thrust--and recharge the batteries that will later power them as motors at take-off. As the plane rolls up the incline, the gravity-assisted braking brings it to a halt directly atop a 3-kilometer-long, multi-story terminal. Unlike a conventional landing, which typically ends at a place that necessitates a 10-minute, jet-powered crawl to a distant gate, this plane needs only to rol l under battery power for a half-minute or so to a gate where its passengers can alight directly into the building below When it's time to depart, the plane heads back down the other side of the incline, relying initially on its electric motors for acceleration, then switching on its turbines as the slope gently rounds to a level stretch for liftoff.

Supposing such changes are technically feasible, what would be achieved? First, if the plane is a typical Boeing 747, about 4,000 kilograms less jet fuel would be burned for each landing and takeoff- roughly 300 gallons of fuel for deceleration, 300 for takeoff, and 300-plus for all the taxiing around large expanses of tarmac in between. (Building the runway like an elongated highway overpass, with the terminal underneath it, would eliminate miles of taxiways and cut down on the airport's use of land, as well as of fuel.) This adds up quickly, because a typical major airport accommodates around 1,000 flights a day--meaning a potential daily savings of close to 1 million gallons of fuel from that airport alone. There would also be a substantial reduction of noise, which has become a cause of rising tensions as growing cities and their airports become jammed closer and closer together in the same space.

These differences could turn out to be critical, because airports-often celebrated for their futuristic architecture and technology-have turned out to be surprisingly damaging in their effects on human and ecological health, and in the past few years their impacts have taken a turn for the worse. In the first two minutes after a 747 takes off, it emits as much air pollution as 3,000 cars, says a study by the Natural Resources Defense Council (NRDC). People living or working near airports have been found to suffer sharply increased rates of psychological impairment, degenerative illness, and mortality. Hundreds of grassroots groups now say it's time to rethink the way we let these giant machines roar in and out of our populated areas.

An Obsolescent Mindset

JIM STARRY ISN'T JUST TALKING about a new kind of runway. To him, the whole mindset that has created the modern major-hub airport doesn't make sense. It's a mindset based on an almost never-questioned assumption--that the solution to rapidly increasing demand for air travel is to provide an ever-increasing supply of land, fuel, and air space. As a result, in its total impact on climate, ecology, and health, today's mega-airport may be one of the most ill-conceived forms of large-scale infrastructure humankind has ever devised-yet it is also one of the least accountable.

Moreover, airports are both multiplying and expanding at a breathtaking rate. In the past few years, huge new airports have appeared all over the world-from Denver to Abu Dhabi to Bangkok. Constructing such an airport is not on the same scale as building a new office tower or highway; it's more like building a city. In China, 18 new airports are under construction and another 21 will have been built by 2005. In Mexico, 20 new airports are planned just for the Baja peninsula. Major airport expansions, which in some respects create even more urban strains than new "green fields" airports carved out of virgin land, are underway in hundreds of cities or suburbs. In the United States alone, the recently enacted Airport Reform and Investment Act for the 21st Century (so-called AIR-21) will subsidize runway expansions or additions at 2,000 airports. New York's heavily congested La Guardia, for example, will increase its capacity by 600 flights per day. And in much of Asia, the pressure to expand is even greater. By 1998, Manila's Ninoy Aquino Airport was operating at twice the capacity it was designed for, and Taipei's Kaohsiung Airport at over three times capacity. Several Pacific Rim governments have embarked on a kind of airport arms race, as they attempt not only to accommodate skyrocketing traffic, but to establish their respective claims to having the pre-eminent "hub" airport of the region.

As Starry ruminates, I become conscious of a distinction I hadn't much thought about before--the difference between air travel and airports. Over the past decade or so, air transport has been increasingly recognized as an environmental threat. It accounts for an estimated 13 percent of the world's carbon dioxide emissions from all transportation sources, and its emissions of this primary green-house gas are expected to grow sharply in the years ahead. Moreover, carbon dioxide combined with other exhaust gases and particulates emitted from jet engines could have two to four times as great an impact on the atmosphere as [CO.sub.2] emissions alone, says a recent U.S. government study. Jet contrails have also been implicated in the development of enormous heat-trapping clouds, which may be escalating the planes' impacts on climate. The exhaust from a single plane may spread to cover as much as 34,000 square kilometers (13,000 square miles). For each passenger on a trans-Pacific flight, about a ton of [CO.sub.2] i s added to the earth's atmosphere. By 2050, says the Intergovernmental Panel on Climate Change (IPCC), the contribution by contrails may be almost twice as large as the contribution from aircraft [CO.sub.2].

But Jim Starry notes that jets are at their worst, by far, when they are on the ground--landing, idling, getting de-iced, taxiing, or taking off. Because airports are designed as they are, most airplanes spend a large part of their working life doing those things. At Denver International, for example, up to 23 planes may be running at "high idle" simultaneously, waiting for takeoff, and some wait up to 40 minutes. In the air, planes produce all that [CO.sub.2] because they're burning fuel so prodigiously. On the ground, jet engines operate at extremely poor efficiency and the fuel is burned very incompletely. Instead of being converted to energy, vapor, and carbon dioxide, huge amounts of fuel are blown into the ground-level air in the form of carbon particulates and volatile organic compounds (VOCs). Starry thinks airports could be designed so that the bulk of that low-efficiency combustion--and pollution--is eliminated.

When he first suggested this, I was reflexively skeptical. To begin with, Starry didn't have the credentials one would like to see from someone who's about to challenge a dominant system. He's always been an outsider--a pilot who has flown thousands of hours, to be sure, and a technician who did some inventive work designing high-altitude balloon launching devices for...