The new kind of suburb wasn't supposed to be so suburban. Packed into 180 hectares, King Farm in Rockville, Md., filled in a patch of lingering farmland just outside Washington, D.C. The village planners left a broad swath of green down the main road, dubbed King Farm Boulevard, that sported along its sides a mix of different types of housing and amenities, such as shops, within walking distance. Down the middle of the boulevard would be the forthcoming train system that would efficiently shuttle new residents to the Washington Metro's Red Line, thereby linking them with the regional public transit system.

As a result of the new design sensibilities, the Congress for the New Urbanism highlighted King Farm in 2008 as an "exciting" development, and the U.S. Environmental Protection Agency cited it as an example of "smart growth." The planned community checked off all the boxes of the "new urbanist" manifesto: a mix of housing types paired with centrally located amenities, designed for pedestrians and cars as well as public transport–oriented.

Instead of embracing that transportation vision, however, the residents of King Farm and the Rockville City Council recently rejected the proposed transit plan—specifically, any light-rail line that would travel down the swath of green explicitly designed to host such a system.

Transit-ready development may mean nothing if local residents are not ready for public transit. And King Farm residents seem prepared to fight the State of Maryland, which bears ultimate responsibility for the decision and still wants to route any transit system through the community. The battle highlights one of the challenges facing so-called new urbanism as it attempts to steer American life away from the car, which has dominated city planning since at least the 1950s.

The new urbanist movement disdained the automobile-centric sprawl, which locked residents into the use of polluting cars for even the most basic trips. The logic of sprawl saw cities eat up a larger and larger share of the surrounding real estate, fueling habitat destruction, smog from tailpipe emissions, runoff from impermeable pavement and other environmental ills.

Communities inspired by a return to the walkable cities of most of human history have sprung up from coast to coast, including places where one might least expect it, such as Los Angeles, Denver and even Salt Lake City, the latter of which has shifted growth patterns away from sprawl. But, as the example of King Farm shows, new urbanism can devolve into the kind of central planning criticized by the very founders of the urban planning school of thought—and can also result in what is essentially a style without substance. "It is more about lifestyle than ecologically sound cities," says sociologist Saskia Sassen of Columbia University, a member of the U.S. National Academy of Sciences panel on cities.

Planner and developer Jonathan Rose of Jonathan Rose Companies of New York City echoes that sentiment. Not owning a car reduces consumption, he notes, but "that reduction in consumption has to come with an increase in happiness. If it comes with suffering—it takes three buses to get where you want to go—then it's not sustainable."

Such suffering seems to be the case for residents of King Farm, some of whom would choose the freedom to be stuck in Beltway traffic rather than face the peril of a community divided by train tracks. "We've come a long way from an era where many cities produced affordable housing through what gets endearingly called 'drive 'til you qualify' strategies," says Uwe Brandes, vice president of initiatives at the Urban Land Institute, a nonprofit research and education think tank focused on land use. "The area of caution associated with transit-oriented development is there's a danger that these areas in cities can become economic and social enclaves. That's a yellow, blinking light."