In the U.S., we’ve long relied on the radical inefficiency of private cars or on rail and bus trunk lines that are only economical in conditions of high density, and which often produce the classic “last mile” conundrum. Public transport is not one of America’s glories: despite many decades of argument for transit-oriented development and other densification policies, close to 90 percent of daily trips are by car, and our sprawling cities are its natural habitat and spawn. As the modal mix rapidly transformed in the early 20th century, much creativity—and loopiness—was devoted to imagining cities reshaped by this technological maelstrom of planes, trains, and automobiles. These visions ranged from the extreme lamination of the vertical metropolis with its multiple modes stacked in space: subways, cars, el trains, pedestrians, auto-gyros, and airplanes shishkebobbed together by elevators; the fantasy of the linear city—an endless band of settlement along a rail line; the “people mover”—a desperately constrained system that attempted to hybridize the car and the railway but which could never rise above the tyranny of its fixed routes or crude technology; the car-enabled edge city that has so complicated the historically centrifugal relations between urban centers and peripheries. What all have in common is the idea of modal separation, systems of isolation in which the least powerful yields to the most: pedestrians give way to bikes, bikes to cars, cars to trolleys, trolleys to trains, etc.

Autonomobiles could present a truly new model of on-demand, point-to-point mobility. Indeed, new shared, responsive systems have already had major impacts on urban patterns and habits. I’ve been working on planning projects for the South Side of Chicago for decades, and the transformations brought about by the arrival of Uber and Lyft in many of its relatively low-density, transit-poor neighborhoods is startling: sparsity becomes practical. My survey is not scientific, but I’m impressed, when using ride-share services there, by how many fellow passengers are on simple errands of moderate distance, otherwise impossible without a personal vehicle. This surely suggests capacious possibilities for urban transformation—new mixes of use, local centers, flexible access to available housing, and networks of sociability that are otherwise thwarted by distance, danger, and inclemency.

Autonomobility will have perhaps its greatest formal impact in altering the most critical matrix of public urbanity: the street. In New York, our streets are both troubled and changing. The widespread growth of cycling, an increase in tree cover, and various managerial efforts to ease traffic via modal mixing have resulted in an even more horizontally laminated streetscape that retains and reinforces modal isolation (sidewalk, bike lane, parking lane, bus lane, traffic lane, median, repeat . . .). We haven’t had the courage of more radical mixing tactics like the woonerf, or shared street, in which all modes coexist in one minimally regulated space. And we haven’t even begun to look at what the recapture of the street might look like if it were considered from scratch, with a radically reformed mix in mind—one in which individually owned cars headed for urban extinction.

One immediate effect could be the liberation of well over a third of street area from use as vehicular storage space. If small-scale, mobile passenger and logistics “particles” were deployed around the clock and on demand, a radical reduction of the number of actual vehicles in service would occur (an MIT study of Singapore suggests the reduction could be at least two-thirds) and with it the liberation—and lubrication—of an enormous portion of urban streets. A variety of robotic and sensor technologies would also allow the efficient utilization of curb space for the transfer of both goods and people from the street to buildings or sidewalks. Indeed, the defeat of the hydra of storage parking and delivery double-parking would have a cascade of beneficial impacts, from eased mobility to reduced pollution and accident reduction to the most important prospect of all: the capture of this public space for more authentically public uses.

In New York City, the street could become a true public service conduit. Traffic would move at a rational pace and bikes could safely join the mix. Sidewalks would be augmented with new uses, including plantings and bioswales, recreational areas, small facilities, and—most crucially and transformatively in New York and other cities that don’t have service alleys—could become the site of operations for managing our solid waste. Replacing our Alpine heaps of plastic sacks of rubbish, a fascinating new architecture of collection, recycling, redistribution, and remediation might arise, anticipating the day when the very idea of waste is relegated to history’s own dustbin. Ultimately, this freeing and reappropriation of the street can be part of a truly localist metabolics in which our air, water, climate, energy, mobility, education, sociability, and nutrition become the central focus of the space we most urgently share.

The horizontal re-lamination of city streets is likely to be accompanied before long by a vertical one as well. Given the imminence of ubiquitous drone movements—as well as the soon-to-appear flying Ubers (the company has already branded its vertical-lift ride-sharing operation “Uber Elevate”)—the space above the city is also sure to be reconfigured. Although the physics (and acoustics) of flying cars will seriously limit their point-to-point capacity at first, NASA and others are already deep into the study of the laminar systems and “rules of the road” to allow large numbers of unmanned aircraft systems (UAS) to operate above and in cities, bringing consumption’s necessities from Amazon and GrubHub. A variety of concepts—including sky-lanes, sky-corridors, and sky-tubes—renew that early fantasy of the laminar city that includes flying vehicles, although most seem to be based on the conventional geometry and parameters of deference that rule roads.

Such revolutionary technology can have fundamental impacts on the form of both current and coming cities. To keep it friendly, however, will demand fighting the growing dominance of the “smart city” mind-set and its uncritical accumulations of “big data” to improve efficiency and control, without much deep thinking about noncorporate forms of desire. This must include the defense of many of our traditional gathering places—our squares, plazas, parks, and sidewalks. The reasons for mobility are not merely logistical. We move to live, to experience the other, to engage the pleasures of place, to collaborate, to enjoy happy accidents of encounter, and to enlarge the space of the political, which demands the verifying integrity of the face-to-face. New mobility systems, however, risk undermining urbanity in favor of a distributive entropy that arrives under the false flag of convenience. Mobility may become more flexible, but it might also become far less accessible (Uber Elevate won’t be cheap), a privilege rather than a right.

This surge of technology could simply yield three-dimensional traffic jams, and it’s urgent that the transition to these new means be finessed with art and determination. Simply adding a new class of vehicles will have the same effect as adding more miles of highway: more traffic. For an autonomobile system to truly fulfill its promise demands radical subtraction. Fewer vehicles and less pavement will mark the truly sustainable cities we might have if we’re authentically dedicated to sharing them equitably and efficiently.