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UC Santa Cruz prof suggests self-driving cars will torpedo parking pricing as effective congestion management policy; “incentive to create havoc”

With no need to park, autonomous vehicles (AVs) will clog city streets and slow traffic to a crawl, according to a new paper by University of Santa Cruz transportation planner Adam Millard-Ball, an associate professor of environmental studies. However, a policy fix could address these problems before autonomous vehicles become commonplace, he suggests. His paper is published in the journal Transport Policy.

In this paper, I identify and analyze a new channel through which AVs will have unambiguously negative environmental consequences—the removal of parking pricing, one of the most effective congestion management policies, from the urban transportation policy toolbox. AVs not only can avoid parking charges through cruising (that is, circling around while waiting for a passenger), but also have the incentive to seek out and exacerbate congestion—even gridlock—in order to minimize costs to their owners.

… In this paper, I show that the parking policies that have allowed dense, urban centers to flourish will no longer be a major curb on vehicle travel in an autonomous vehicle world. First, AVs remove the parking proximity constraint: at high levels of automation, AVs have no need to park close to their destination, or even to park at all. Second, AVs can behave strategically in order to minimize the costs to their passengers or fleet owners, primarily through seeking out and creating their own traffic congestion through choosing to circle on streets where they can drive the most slowly.

… This paper suggests that the parking behavior of autonomous vehicles would land cities with a twofold blow—a dramatic drop in the cost of parking that encourages more trips by car, and greater vehicle travel and congestion from each trip due to cruising, returning home, and traveling to free on-street spaces. The reduced price of parking would likely increase vehicle travel to dense, urban cores by 98%, while cruising and travel to and from remote parking spaces would add a further 8%.

Fundamentally, AVs will negate one of the central pillars of Transportation Demand Management programs that seek to reduce vehicle travel in downtowns, university campuses and other employment centers.

—Millard-Ball (2019)

That scenario of robot-fueled gridlock is right around the corner, according to Millard-Ball, who says autonomous, or self-driving, vehicles are likely to become commonplace in the next five to 20 years. Millard-Ball is the first researcher to analyze the combined impact of parking costs and self-driving cars on city centers, where the cost and availability of parking is the only tool that effectively restricts car travel.

Parking prices are what get people out of their cars and on to public transit, but autonomous vehicles have no need to park at all. They can get around paying for parking by cruising. They will have every incentive to create havoc.

—Adam Millard-Ball

Under the best-case scenario, the presence of as few as 2,000 self-driving cars in downtown San Francisco will slow traffic to less than 2 mph, according to Millard-Ball, who uses game theory and a traffic micro-simulation model to generate his predictions.

It just takes a minority to gum things up,” he said, recalling the congestion caused at airports by motorists cruising the arrivals area to avoid paying for parking: “Drivers would go as slowly as possibly so they wouldn’t have to drive around again.” Free cell-phone parking areas, coupled with strict enforcement in loading areas, relieved the airport snarls, but cities will be hard-pressed to provide remote parking areas for self-driving cars at rates lower than the cost of cruising—which Millard-Ball estimates at 50 cents per hour.

Even when you factor in electricity, depreciation, wear and tear, and maintenance, cruising costs about 50 cents an hour—that’s cheaper than parking even in a small town. Unless it’s free or cheaper than cruising, why would anyone use a remote lot?

—Adam Millard-Ball

Regulation also falls short because, as Millard-Ball puts it, “It’s difficult to regulate intent. You can pass a law saying it’s illegal to drive more than 10 minutes without a passenger, but what if the car is picking up a parcel?

Millard-Ball proposes congestion pricing—which can take different forms but essentially amounts to a user fee—as a solution. In London, motorists pay a flat fee of £11.50 (about $15) to enter the city center. Singapore and Stockholm employ similar models. More sophisticated models could charge by miles driven, or assign different fees to particular streets.

Economists and environmentalists agree that congestion pricing effectively reduces congestion and pollution, but it’s a politically fraught strategy because it raises the ire of commuters. Millard-Ball sees an opportunity here.

As a policy, congestion pricing is difficult to implement. The public never wants to pay for something they’ve historically gotten for free. But no one owns an autonomous vehicle now, so there’s no constituency organized to oppose charging for the use of public streets. This is the time to establish the principle and use it to avoid the nightmarish scenario of total gridlock.

—Adam Millard-Ball

Moreover, he noted, self-driving cars could be outfitted with devices that would give policymakers options for levying fees based on location, speed, time of day—even which lane the vehicle occupies.

The fees could raise money for cities to improve transportation. The idea is to do it now before autonomous vehicles become widespread.

—Adam Millard-Ball


  • Adam Millard-Ball (2019) “The autonomous vehicle parking problem,” Transport Policy, Volume 75, Pages 99-108 doi: 10.1016/j.tranpol.2019.01.003



This scenario is the mobile billboard squared.  The point of the mobile billboard is to put messages in people's view when they're stuck in traffic, but they add to the congestion.  All such things need to be banned as public nuisances.


I think his model is severely broken. At any give time during the day SF has thousands of vehicles motoring downtown. A good portion of those are searching for parking and frequently they are parking far from their destination. Whether he realizes it or not this is one of the primary reasons for the success of Lyft et al.


Interesting and useful concern.
However, such kinds of algorithms can be monitored and legally regulated.
Moreover, once fully autonomous driving electric cars are available, taxies will be so cheap and convenient that they will most probably take over private driving.
A taxi ride will probably be much cheaper than the parking charges today.

An electric car that can drive 1,000,000 miles before it needs to be replaced, and costing $50,000, costs about 5c/mile capital investment cost.
The "fuel" cost is less than 2c/mile.
Let's say a "total overhead cost" of 5c/mile.

Total : 12c/mile .
Free competition will ensure reasonable profit margins, so this will be much cheaper and more convenient than driving your own car.

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