BUT THE FUTURE OF AVIATION in America is by no means secure. Crowded airports are not likely to see relief any time soon; expansion by building new runways is a nonstarter, seen as a sign of blatant disregard for the environmental impact of air travel—as evidenced in the protests sparked by Heathrow's proposed expansion. As we conducted our research, we started to wonder: Is there a way to hybridize the interests of rail and air? We considered models for air and rail working together, not as enemies competing for resources and passengers. In many ways this is already happening. For instance, if you buy a ticket from JFK in New York to Exupéry in Lyon, you'll fly to Paris and then take the high-speed rail to Lyon.

A good chunk of the runway capacity in the desert Southwest is taken up by flights between LA, Phoenix, and Las Vegas. Those flights are about as long as the trip between Tokyo and Osaka, which happens to be the world's most successful Shinkansen, or bullet train, route. Even though it takes one and a half hours to fly from one city to the other and an hour longer by rail, the Shinkansen enjoys 86 percent of the market share.

Looking at these models, we decided to propose a business-to-business partnership between rail and air. We realized that, in order to build a high-speed rail network, we had to sell the idea that doing so would prove a boon to air travel. We had to convince companies like Boeing, Lockheed-Martin, and Honeywell, which are the bedrocks of the region, and the politicians that represent them. So we made this argument: Rail is not a separate infrastructure but rather a component of the existing airline infrastructure; by replacing the myriad short-hop flights with more efficient rail service, we're actually freeing up runway capacity for the airline industry to use on longer, more profitable routes.