THE SECOND COMING OF CARS: Will Self-Driving Cars End Congestion, Improve Safety, and Save the Environment?

Self-driving cars, a.k.a. autonomous vehicles (AVs), are all the buzz these days.  They are already being rolled out for real-life testing; within a very few years, sooner than anyone believed possible a short while ago, they will soon be nationwide.  Whether we want them or not; whether we are ready or not, they are moving from “Level 3” autonomy, where a human must be available to retake control, to "Level 5," cars that go on their own.  The breathless headlines announcing their arrival amplify our society’s techno-utopian impulse, with enthusiasts (and marketers) describing the countless ways AVs will revolutionize and improve nearly every aspect of our lives and society.  We are being told that autonomous vehicles will come to the rescue of our increasingly dysfunctional transportation system.  Car crashes won’t happen.  Pollution will decrease.  Congestion will go away.  Parking lanes will be turned into parks or bike lanes.  Access disparities will decrease for low-income and rural areas.

At the risk of being labeled a Luddite, I don’t believe it. 

Change: Yes.  And lots of it; much of it disruptive.  But improvement?  No more likely – in fact, probably less likely – than damage.  The only thing that has a chance of creating a more positive outcome is proactive regulation of the product and its use.  As ZipCar founder, Robin Chase, has been pointing out, we are faced with a Heaven or Hell choice.  Without successful strategies to steer us towards positive outcomes, AVs will not eliminate traffic congestion, reduce aggregate vehicle miles travelled (AVT), injuries, air pollution, or the need for parking, and may actually make it all worse.

The good news is that so much of what we need to do to maximize the benefits, and avoid the catastrophes, of the seemingly inevitable onslaught of driverless cars are the common-sense things we have already started doing because they are worthwhile under any circumstances -- prioritize modes that move the most people, cause the least environmental damage, and equalize access; build more transit, bike lanes and sidewalks; price highway access, curb access and parking; etc.  However, the coming of AVs means we have to do a lot more of it, sooner.



Autonomous vehicles (AV) may reduce traffic crashes, at least after a potential demolition derby transition period when driven, human supervised, and self-driving vehicles share the road, or in areas (such as urban downtowns) where driven cars are forbidden to go.  (The tech firms behind AVs have already begun protecting themselves: “California Limits Crash Liability For Self-Driving Cars”)  AVs will only reduce pollution, at least in cities, if they are electric – but there is no current reason to assume that they won’t use fossil-fuels.   If electric, they do open the possibility of drawing on renewable energy, but our national grid will continue to draw on coal and gas for years to come; and the total energy needed to move a vehicle depends on its weight, with electric cars not inherently lighter than gas-powered ones because of the bulky batteries – weight mostly goes down in tandem with size, and American’s seem to have an unending appetite for bigger vehicles.  

Congestion may go down if people are willing to share AV trips, as with a shared Lyft/Uber ride, but will increase if the AVs convenience and low cost are enough to pull people out of mass transit, or if individually-owned AVs are instructed to keep circling the block until their owners return from shopping or work – a “zombie car” apocalypse probably only avoidable through congestion pricing!  AVs will be affordable if they are scaled into fleets, with users only paying for the distance they travel, but will remain out of reach of the bottom 40% of our population if the Tesla model of individual/family ownership prevails.   Even if we regulate AVs to require electric fleets, keep vehicle weight and size low, and incentivize group trips, it is probable that road use (aggregate Vehicle Miles Traveled -- VMT) and parking will only go down if there is no need for the car to drive around (or park) between letting one group off and picking up the next and if lower commuting costs (and continuing increases of in-town housing prices) convince people to move even further out of town requiring even longer commutes. 

In any case, rather than replace mass transit, AVs will not eliminate the need for a vast upgrade and expansion of urban-core mass transit systems.  There is no possible way to have enough cars on our roads to simultaneously carry the hundreds of thousands of people who go to work and back home every day at roughly the same time.  And if there were enough cars, none of them would be able to move, even if their AV-brains allowed them to be mere inches apart – which is exactly how they’d end up.



Of course, there are some socially valuable functions for properly regulated AVs to play, as there is for almost all technologies.  First, they are an effective adjunct to mass transit. Transit is irreplaceable because as Jarrett Walker noted in CityLab, “an efficient mass transit network is designed to do most of what thousands of people want. It is by being mostly useful to so many people that buses and trains attract lots of riders. And carrying lots of riders is how buses and trains deliver so much liberty and opportunity to citizens while taking so little space.” In lightly settled area, AV vans holding 6 to 12 people might be a flexible and low-cost way to expand the transit system assuming they are convenient and cheap enough to attract users.  In denser areas they are an excellent method for handling the last mile problem of getting people from dispersed homes to train, trolley, and bus stations – most of which is along city roads rather than highways.  (However, without congestion pricing or other disincentive, people who hire an AV to get to the train station are likely to skip the train and stay in the car all the way downtown.)  Some of the AVs used for this can later serve to bring off-peak commuters to work at times when mass transit isn’t scheduled to run, preferably as a group/shared ride.  Other AVs can remain in the community, both within city neighborhoods and in suburban towns, for local trips.   All these uses fit into the Uber/Lyft and taxi model of short rides. 

AVs might even be useful for long, family trips to places not well served by train or bus lines – fitting into today’s car-rental business model of full- or multi-day use.  However, one-way trips to rural areas, where it is unlikely that a second user will want to hire the vehicle within a short time after the end of the first person’s trip, will probably invoke a surcharge.  And the long time it would take for a car to get from its main activity area to a rural user may discourage that kind of use – unless rural agencies such as Regional Transportation Authorities (RTAs) own a small fleet based in their area.

Looking beyond cars, AV buses might be another way to merge the technology into mass transit, particularly if cities establish bus priority lanes and intersections.  This might free up the bus (or trolley or subway) staff to focus on customer service – we should not allow the MBTA to use AV as an excuse to leave bus riders without any staff support during their trip. 



Whether future AV fleets are owned by public agencies or private firms is not ultimately the issue, although public benefit must shape the context and market for profit-seeking.  A broad coalition is beginning to coalesce around “Shared Mobility Principles for Livable Cities”. In addition to proactively requiring that all AV’s be electric and creating a variety of incentives for them to be fleet-based rather than individually owned (or putting prohibitively high excise and registration fees for non-electric or individually-owned AVs), there are other steps that government should take to lay the foundation for the successful introduction of this new technology such as raising the gas tax and imposing a carbon-emissions fee.  We need to remember that 37% of Boston’s households do not currently own a car.  The mobility needs of these people need to be a central concern for policy-makers.

Creating bus-priority lanes and intersections has already been mentioned, but expanding the network of High Occupancy Vehicle (HOV  -- preferably requiring 3+ passangers) lanes for cars with more than one person is another reform that will be both helpful today and set a good direction for the future.  Imposing a VMT tax on non-electric or individually-owned AVs will help reduce their wasteful use.  Congestion pricing has already proven to reduce down-town congestion and will help keep individually-owned AV’s from undercutting transit, if combined with a “time-in-the-area”  fee it could also encourage owners to send their empty cars out of the downtown to park.  This should be complemented with demand-responsive (market-rate) parking fees in commercial areas that will reduce today’s circling-the-block problems while keeping future AV vehicles from stuffing up spots as well. 

More fundamentally, roads need to become much more people-oriented rather than vehicle-focused.  Pedestrian space needs to be expanded along with safe spots for sitting, playing, and socializing.  Intersection’s need longer Walk signal times.  Bike facilities, with protected bike lanes on streets with high car volumes or speeds, need to be an automatic part of every street repair.

No technology will, by itself, solve our society’s growing inequalities.  But that’s no reason to allow it to get worse; we need policies that will ensure equal access to AV fleets in low-income and minority areas and that improves their affordability for people whose budgets are already stretched thin.

Cities, rather than the state, own most of the roads and all of the curb-space.  They need to use that ownership to impose controls on the rapidly approaching AV era.  We need to rethink – probably expand -- the number and location of truck and shared-vehicle unloading spots.  We need to “price the curb” to generate the revenues needed to monitor the evolving situation and implement improvements.  But we should also more boldly start putting a price on use of the travel lane through congestion pricing, permit fees, and other mechanisms.

Finally, we need to keep shaping the land-use context that shapes our transportation choices by doubling down on smart growth zoning, encouraging more mixed use developments where people can live and work nearby,  steering development towards denser transit-accessible locations, and requiring all firms with more than 20 employees and all retail locations with more than a half-million dollars in gross sales to implement strong Transportation Demand Management plans to reduce single-occupancy-vehicle use by staff and customers.



Frequently, the introduction of a radically new technology triggers a similar cycle.  First, it becomes fuel for the techno-utopian impulse, with enthusiasts (and marketers) describing the countless ways it will revolutionize and improve nearly every aspect of our lives and society.  Then comes the business and power-protection filtering, where the technology gets shaped to fit into the most profitable uses that do not upset the larger hierarchies of our social system.  Third is the roll out, when the transformative impact either manifests or (at least temporarily) disappears while its use becomes increasingly integrated into daily life. If the technology does take off, does become a commodified normal part of everyday activity, people start pushing its boundaries, using it for purposes its commercial pushers never contemplated – and perhaps turning it into a tool for greater equality and general well-being after all.

Let’s hope that with Autonomous Vehicles we can run through the cycle quickly.


Thanks to Robin Chase and Tony Dutzik for comments on previous drafts.


You may also find these previous, related blog postings interesting. 

> Smart Cities, Power Politics, and Quality of Life:  Technology and what it’s used for

> Redefining Transportation:  From Moving Vehicles to Place-Making   

> Digital World Creates New Road Functions & Requires New Design Standards

> The Interacting Ingredients of Livable Cities:  Complete Streets to Interior Design, Transit to City Planning, Art to Education

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