With the world rapidly urbanizing, and cities already choking on smog and facing nightmarish traffic caused by autos, what transportation options will get people into, out of, and around the world’s growing metros?

Ride Sharing’s Impact on Cities

Shared mobility services have been proposed as a solution to urban congestion. When Uber and Lyft launched a decade ago, proponents of this model of peer-to-peer “ride sharing” claimed it would revolutionize public transportation to the point of replacing it. Opponents of a 2016 ballot measure to fund transit projects in Detroit wrote, “The proposal spends billions on old transit tech like buses and rail while other cities are contracting out transit services to Uber, Lyft, Chariot and others that provide door-to-door service at substantial savings.”

In the meantime, we’ve learned that peer-to-peer ride sharing services, better called ride-hailing services since they primarily function as taxis carrying individual passengers, have made traffic 180 percent worse in some cities. They have over-supplied the market with vehicles that are empty most of the time, on average adding 2.8 miles of traffic for every mile they carry passengers. Those vacant miles, called deadheading, lose money for drivers, and are what cause congestion on the roads. Consumers may see lower prices for transportation with ridehailing than with taxis or public transit because investor money subsidizes the rides. These subsidized, below market value ride prices are why ridehailing businesses lose billions of dollars each quarter (Chariot went out of business in 2019).

AVs to the Rescue

Enter autonomous vehicles (AVs), a possible solution to gridlock and pollution. Read “Eight ways driverless cars will improve our lives.” Here’s the Cliff notes version:

• Carbon emissions will be dramatically reduced
• Traffic will disappear
• Everybody will have more free time
• Productivity will increase
• Mobility for all people will dramatically improve

A 2018 article in The Atlantic went so far as to recommend that New York City give up on its aging subway system and turn it into an underground AV highway. “Instead of fixing the old trains, let’s rip out the tracks and fill the tunnels with fleets of autonomous vehicles running on pavement.”

Since then, expectations for AV bliss have cooled considerably, starting with the notorious fatal crash of a self-driving Uber vehicle in Arizona, followed by revised forecasts for when self-driving technology will be safe enough for prime time. But it is also becoming apparent that autonomous cars alone, even when they are perfectly safe, won’t solve urban congestion and pollution. They could make it twice as bad by some estimates, if the primary use case for AVs is as private cars.

It makes sense that if people swap out their private autos for individual AVs, traffic won’t get much better. Emissions could certainly drop if the vehicles are electric. Congestion will get worse, however, because it will be cheaper for AVs to drive around empty or return home rather than park. Other scenarios suggest that the vehicle might run errands for the owner after the commute, or be used by the kids after school. All of these possibilities would result in more traffic.

These are some of the scenarios that researchers have warned about. All of this will dramatically increase what transit experts call Vehicle Miles Traveled (VMT). The added VMT will come from the same number of vehicles on city streets, traveling many more miles. If we ignore public transit in the interim, people will have fewer alternatives, further worsening traffic.

Private autonomous vehicles would be a “disaster,” researchers at the Technical University of Vienna said. They found that VMT could increase as much as 59 percent. That’s not as bad as a study from the University of California at Santa Cruz, which found traffic in San Francisco would at least double if private AVs become the norm.

The author of a report on the potential impact of AVs on urban traffic at the technical university of Zurich concluded the promised benefits of autonomous vehicles will be realized only “if autonomous cars cannot be acquired by private individuals.”

Three Revolutions

Returning to the dreamy vision of reduced traffic and pollution, more productivity and free time for all: can it happen? Many believe it can, but only if we can shake free of our attachment to the private, personal auto as the primary mode of transit. Advocates of shared mobility services argue that the combination of technology and smart services can move the same number of people around cities with a fraction of the number of vehicles with no loss of convenience for travelers.

Three revolutions are coming, according to a report from the Sustainable Transportation Energy Pathways (STEPS) program at the University of California at Davis and the Institute for Transportation Development and Policy (ITDP): Electrification, automation, and shared mobility. The study analyzed transportation patterns in eight global markets and found that:

• Electrification can reduce auto energy use by 70 percent
• Automation can improve safety and cut the cost of transport by 40 percent
• Shared mobility can reduce congestion by 50 percent

The first two revolutions can’t happen without the third. “Without a concurrent shift away from personal vehicle ownership and toward ride sharing, the potential for autonomous electric vehicles to reduce traffic and sprawl are extremely limited,” the report said. “If passenger vehicles do not become predominantly shared by 2050, our cities will continue to be chocked by congestion,” said ITDP’s Jacob Mason. “Instead, the urban residents should ride electric, automated, and shared vehicles into a cleaner and healthier future.”

Don’t Forget Public Transit

Most of these shared mobility models provide short trip services, so-called “last-mile” coverage of routes to and from transit hubs. Reaching stations is one of the main obstacles to mass transit ridership. The optimal use of shared AV services is to get more people on buses and trains that are, for the most part, very efficient at moving millions of people in and out of cities each day.

The Organization for Economic Cooperation and Development modeled traffic in Lisbon, Portugal, and found that shared AVs coordinated with high capacity public transport would cut traffic by 90 percent.

“What’s often talked about is micro-transit or vanpooling,” ITDP’s Mason said. “With vehicle automation and better technology, those could really supplement the existing public transport network in lower demand areas.” Reaching low-demand areas provides new access to jobs. The Union of Concerned Scientists and analysts Fehr and Peers analyzed multiple shared and unshared mobility scenarios and found that pooled services would increase access to jobs, as much as doubling the number of opportunities that workers could reach. Conversely, unshared services reduce this benefit by 80 percent.

Efficient Ride Sharing

Real ride sharing, carrying multiple passengers with similar trip origins and destinations, requires services that are far more efficient than today’s peer-to-peer models. Matching riders with vehicles such that trip times are predictable and convenient requires optimized services and advanced dispatching, ride matching and routing algorithms that maximize vehicle occupancy and utilization while minimizing deadheading. Software that continually monitors supply and demand matches riders with vehicles for shared journeys, and supports guaranteed convenience for travelers and business outcomes for operators can do this.

A Shared Future

Is the vision of cleaner, uncluttered cities, with convenient shared mobility services stirring enough to get people to give up their cars? Some are skeptical, but others point out that for generations, we were conditioned to never get into cars with strangers, and now most of us do just that with Uber and Lyft. Barring restrictions on private vehicle ownership, the key to the adoption of shared mobility will likely be its efficiency and cost.

Perhaps we’ll need to revisit another childhood lesson. As Lewis Fulton, co-chair of the STEPS program, sums it up: “All the futuristic automotive technology being developed could make our cities more livable and the air more breathable, but only if we take sharing seriously,” he said. “When it comes to cars, what we learned early in life still holds true: sharing makes everything better.” So simple. Sharing could make the future safe from the perils of AVs and for their benefits.