FORTUNE -- Ever since cars hit the mass market in the U.S., urban developers have prioritized the flow of automobiles as they plan cities.
But building cities to support highway infrastructure does not necessarily provide the best quality of life for residents, according to a group of panelists at Fortune's Brainstorm Green conference in Laguna Niguel, Calif.
"The age of the highway city is over, we can't afford it, and it's not desirable," says Peter Calthorpe, a principle at Calthorpe Associates, an urban design and architecture firm. Calthorpe argues that as more of the world moves into urban environments -- he says there will be 3.5 billion people living in developing world cities by 2025 -- they will want fun, livable urban places. Cities can be all those things, he says, without being designed with cars in mind.
City mayors are already concerned about reducing traffic congestion, says Eric Spiegel, the president and CEO of Siemens (SI). On the upside, reducing traffic will not require a technological breakthrough, he says. "People talk about new innovations, but we already have a lot of the technology to get cars off the road."
Many transit innovations are coming from the developing world. For example, Western nations are currently studying bus rapid transit models already in place in Latin America.
Panelist Jay Carson, chief executive of C40 Cities Climate Leadership Group, cited a recent project by the mayor of Rio de Janeiro, Eduardo Paes, who is implementing bus rapid transit to help cope with the city's transportation needs leading up to the 2016 Olympics. Bus rapid transit (BRT) dodges some of the pitfalls of the current systems. Using BRT, people pay for their tickets before the ride, saving time from idling at stops while passengers board and ultimately reducing the system's costs. For the system to work smoothly, leaders in cities must also work to strictly enforce penalties for cars that camp out in bus lanes.
Though the carbon savings are significant, Paes is not billing his efforts as a big green initiative, Carson says. Instead, he's capitalizing on the fact that better public transit organically improves the quality of life for residents. In part, well-mapped transit improves quality of life in cities because it minimizes the overall impact of transit vehicles. That's the irony of this kind of approach -- the best transit systems actually cut down on the amount of machines shuttling people back and forth.
"I actually coined the phrase transit-oriented development, and I'd like to shed it," Calthorpe said. "The answer has more to do with walking and biking -- shoes, not tires."
Or at least, not car tires. It's an interesting thought -- that cars will be a much less obtrusive feature of the cities of the future. Hopefully, it's a point that leaders at car companies will address. (General Motors (GM) CEO Dan Akerson is joining us at Brainstorm Green later today.) How will automakers adjust when cars don't come first in how we think about cities?
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