When cars no longer rule

A city is not a problem to be solved.

So says Marshall Brown, architect, urbanist, associate professor in Princeton’s School of Architecture and the director of the Princeton Urban Imagination Center.

In Brown’s view, a city is a reflection of our social, political and cultural values. New technologies are not so much solutions as opportunities.

“People ask how will new technologies change our cities, but that is backwards,” Brown said. “The question is, how do we want our cities to change, and then how do we leverage the technologies to get there?”

The technology that has been on Brown’s mind lately is the autonomous vehicle, and not just the driverless car.

“There will be stuff moving around all the time,” said Brown. “Instead of the garbage truck coming to your house, the bin will just roll away when it is full.”

Brown has been asking questions about how technology will change urban mobility since 2015, when he was on the faculty at the Illinois Institute of Technology in Chicago. Questions like: How will we turn 20th century streets, roads and parking lots into 21st century infrastructure? And how do we do it in ways that maintain or enhance the livability of cities?

Signs are for humans

Although today’s automakers are investing vast resources into self-driving cars, they’ve given far less thought to the design of the physical urban infrastructure to support them, Brown notes. Take road signs. They were made to tell human drivers what to do.

But driverless cars don’t need signs — they can get instructions from the road itself. Autonomous vehicles can navigate via cues embedded in roads, by recognizing patterns, textures or materials.

To explore this idea, researchers in the Princeton Urban Imagination Center’s Vehicle to Terrain project — which includes faculty collaborators in architecture and Princeton’s School of Engineering and Applied Science — are designing and testing ways that cars can communicate via innovations in machine learning, robotics and new materials.

The team, which included architecture graduate students Kaitlin Faherty and Yidian Liu, who earned their master’s degrees in 2021, milled wood blocks and used lasers to etch patterns into the blocks embedded in the road. “We store information in the pavement, and this is environmentally sound, and is more beautiful, which is something that we care about in architecture,” Brown said.

Parking — not

Another question is how autonomous vehicles will change the nature of pavement, the ubiquitous and vast impermeable cap over the urban landscape. Pavement causes numerous challenges. The impervious surface enables flash flooding and prevents groundwater aquifers from refilling. Heated asphalt contributes to the “heat island effect,” in which urban areas experience higher temperatures than outlying regions. The pavement steals spaces that could be covered in green spaces.

Will autonomous vehicles allow us to shrink the pavement footprint in the urban environment by altering roads and parking lots? Parking by definition is stationary, but with driverless cars, the future of parking could be mobile.

Personal automobiles mostly sit unused while their owners are at work or at a play or concert in the urban environment. When cars can drive themselves, they can navigate to lots far from urban centers, although Brown cautions that it is important to guard against low-income areas becoming the parking lots of the future.

Self-driving vehicles can enhance equitable mobility. Although public transportation can help alleviate traffic and pollution, it presents challenges for the very young, the disabled, the elderly and others who may have trouble with stairs, escalators and crowds. “Urbanists might glorify the bus or the train, but public transportation is not the best option for everyone,” he said.

Changing the nature of space and time

We think of space and time as fixed. A minute is a minute. A mile is a mile.

But, Brown points out, technology has the potential to alter space and time. What was once a 12-hour horse-and-buggy ride has become a 30-minute hop by automobile. Schools, stores and workplaces that once were a day’s walk are now an hour’s drive.

With autonomous driving, what transformations will occur?

One change is that mobility will no longer be limited to people with driver’s licenses. People who cannot drive — or children who want to go to a friend’s house — can just summon driverless vehicles that will take them to their destinations.

“Once you start thinking even a little bit about the impact of these technologies,” Brown said, “it explodes into thinking about everything at once.”