In the race to bring driverless cars from a futuristic fantasy to a present-day reality, developers have touted a plethora of advantages, from reduced traffic congestion on roads to improved safety thanks to the elimination of human error. But the potential widespread implementation of driverless cars could also have profound impacts on the form of our urban environments, fundamentally reshaping infrastructure and land use. As recently as a year ago, this new technology was seen as decades away; however, recently Elon Musk, CEO of electric car maker Tesla, predicted that driverless cars will be capable of making cross-country treks within about two years, and a pilot program in the United Kingdom city of Milton Keynes plans to launch a fleet of driverless pod-taxis by 2018, matching Musk’s timeline.

The driverless car future could be just around the corner, and the normally slow-changing infrastructure of cities could be forced to apply quick fixes to adapt. At the same time, the full potential of driverless cars cannot be realized without implementing significant changes to the urban fabric. So how will driverless cars change how our cities work, and how will our cities adapt to accommodate them?

Perhaps the most tangible impact of the driverless car future will be a reduced need for parking infrastructure. If cars can park themselves, parking infrastructure will no longer need to be located within walking distance of the final destinations, and could instead be concentrated in remote locations, or at the periphery of city centers. Facilities for self-parking cars can also save space by eliminating the need for human infrastructure such as walkways, stairways, and elevators. Large-scale implementation of public robotaxi systems could even eliminate the need for parking altogether. All of the area that was once dedicated to parking could then be replaced with public open space, or other types of development. In some cities, as much as one-third of the total land area is devoted to parking, and freeing even a portion of that space for alternative uses represents significant opportunities. The city of Somerville, Massacusetts is already exploring opportunities for more efficient use of parking space utilizing self-parking cars, as part of the Audi Urban Future Initiative.

Save this picture! Somerville's plan to reduce parking space using self-parking cars. Image Courtesy of Audi

The vision for the city of Milton Keynes, in the UK, takes a somewhat opposite approach, where a new pilot program plans to implement a fleet of 20 to 30 public driverless pod cars that will share space with pedestrians to provide a transportation alternative in the city center, especially for those with mobility issues or small children. In this plan, city residents will still need to drive to existing parking facilities located around the periphery of the city center, and then transfer to the driverless cars to get around the central core. But the plan in Milton Keynes has come at the expense of public transportation, where leaders in the low-density city have deemed light rail and tram options too expensive.

This interaction between driverless cars and public transportation will be vital to the future of cities. While this new technology has the potential to support public transportation networks by filling the so-called “first mile, last mile” gap, driverless cars will not be a replacement for public transportation. Indeed, studies have found that robust public transportation networks will be vital to the successful implementation of driverless cars, because rather than reducing the amount of driving, driverless cars may actually increase the total vehicle miles traveled. A wholesale adoption may lead to more congestion, similar to the “induced demand” phenomenon (in which widening roads actually makes traffic worse).

This challenge is exemplified by one of the concept vehicles envisioned by global design consultancy IDEO in their Future of Automobility project. The WOW, or “Work on Wheels” concept blurs the lines between vehicle design and architecture, reimagining the driverless car as a mobile office where, “the workplace comes to you instead of the other way around.” The efficiency of working on the go–whether on the way across town to a meeting, or as a remote workspace like those found at construction sites–presents attractive productivity gains, but it also represents a new type of vehicle on the roads, potentially adding to congestion.

However, while these changes to the ways we use vehicles threatens to increase traffic, developers of driverless cars are working on solutions - even to the extent that one of the most commonly cited benefits of driverless cars is the potential reduction in traffic congestion. Driverless cars will be able to drive closer together, and communication between vehicles will enable seamless traffic coordination. Even in urban street grids, where frequent intersections can snarl traffic, driverless cars offer the possibility of cross-town trips without stopping. A recent simulation from the Senseable City Lab at the Massachusetts Institute of Technology illustrated how communicating vehicles could pass through a busy urban intersection in multiple directions, simultaneously, and without colliding, as shown below.

Even in large and busy and intersections, like this example, full adoption of driverless cars could lead to a city without the need for traffic signals. But while the potential for dramatically increased traffic efficiency is certainly compelling, savvy viewers of the above simulation will note that it does not include pedestrians or bicyclists, vital components of the urban environment. Indeed, some simulations have suggested that if driverless cars have to stop at intersections to accommodate pedestrians or conventional vehicles, slower acceleration rates, similar to trains, could actually make traffic worse. Cities around the world have recently made enormous strides in integrating pedestrians, bicyclists, and automobiles, and improving safety, but if traffic efficiency becomes the primary motivation for adapting cities to driverless cars, we may see a return to the separation between automobiles and pedestrians that was popular in the middle of the 20th century.

Save this picture! Will driverless cars lead to separation between automobile and pedestrian infrastructure, like this skywalk in Houston, Texas?. Image © flickr user mwschaff, licensed under CC BY-NC-ND 2.0 via Commons

This potential future is already reality in some cities around the world. Cities like Minneapolis and Calgary have extensive skyway systems, enclosed elevated walkways that connect neighboring buildings, designed primarily to protect pedestrians from harsh weather. But these systems have also faced criticisms for stifling the vitality of the city streets, and they raise issues over which of the city’s residents have access to these privately-controlled public spaces.

Save this picture! Map of Calgary's +15 Skyway Network. Image via Wikimedia Commons, Public Domain

But segregated streetscapes are not the only solution. In a 2010 entry to the Audi Urban Future Award, Bjarke Ingels Group (BIG) proposed a vision where driverless cars, pedestrians, and bicyclists occupy a shared street space, with a network of sensors embedded in the road providing real-time data to automobiles to prevent collisions. This vision would eliminate the separations between sidewalks, bike lanes, and car lanes, while ensuring safety for all road users. Although this proposal would require a complete restructuring of existing city streets, BIG’s concept suggests that streets could seamlessly adapt throughout the day, transitioning from entirely vehicular to entirely pedestrian, and every iteration in between, depending on demand and traffic patterns.

Save this picture! BIG's vision for integrated urban space using driverless cars. Image © BIG

Clearly driverless cars will present a wide range of both opportunities and challenges for our cities in the future, and that future is quickly becoming reality. The technology associated with driverless cars has the potential to reshape our cities in ways that provide more transportation options, while also improving public space, and releasing valuable land for more productive uses. But they could also lead to a doubling-down on the car-centric planning principles that dominated so many cities in the second half of the 20th century. Architects, designers, and planners need to start thinking about how to plan for driverless vehicles now, but a recent article from CityLab suggests that the planners responsible for crafting urban transportation policy in the United States’ biggest cities have not even started thinking about how to address driverless cars. If Elon Musk and the city of Milton Keynes are correct in their predictions, there isn’t much time left to prepare.