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_V_astly _M_ore _T_ravel

A new paper points out how consumers may respond to autonomous travel.

A few months ago I was dreaming of a glorious autonomous electrified future. Yet sometimes science is the equivalent of a bucket of ice water applied during a heavenly nap.

Let’s recap. Electric vehicles powered by 100% clean renewables may do away with almost all local and global pollutants. Awesome. Autonomous vehicles, in theory, will be able to better dispatch individual cars to uncongested routes, use less space (since they possibly require less distance between cars) and possibly make fewer mistakes – leading to less congestion and possibly fewer accidents. Dreamy. But what this dream holds constant is vehicle miles traveled – namely how the demand for travel will change in response to this new technology. Lucas last week already told us that Millenials will not save our collective butts by driving less. Looks like they will not drive any less. And the studies Lucas quotes do not take into account autonomous driving.

So how do we figure out whether consumers will put more or fewer miles on their vehicles once they have access to autonomous transportation. One approach is to make all kinds of assumptions. The other approach is to get creative. My engineering colleague Joan Walker and collaborators decided to do the latter. In their experiment they provided 13 households with free chauffeur service for 60 hours for one week.

Here is what that looked like. A person was sitting in your car in the driveway. You could get in the car and they would drive you wherever you want to go. Or you could tell them to go get your dry cleaning, get you a unicorn frappucino at Starbucks or pick up the kids. Sort of what we would hope cool cars of the future would be able to do. The key here is that the chauffeur drives your car. You still pay for the gas, lease payment etc. So this is supposed to mimic the “autonomous” part.

Is this a perfect experiment? No. Joan is the first to admit this. Is this important progress? Max would argue, yes! But it’s important to consider a few ways in which this experiment is different from the future reality it is trying to mimic. For one thing, these folks know they were being studied. And there’s plenty of evidence, dating back to this study in the 1949, that people can behave very differently when they know they are being watched and evaluated. A second concern is that a chauffeur in your drive way feels different than an autonomous car of the future. In a truly autonomous car, every seat is available for a passenger. So if your car seats 5, an autonomous car would have room for 5, not 4 passengers, as in a chauffeured car. Also, if you’re like me, you enjoy the quiet solitude of the car. You may be inclined to not take a trip if you have my antisocial tendencies, while you would be happy to do so with Siri! You may not believe that cars will ever be able to pick up your Starbucks. Also, the chauffeur in some sense is just another human driver, prone to accidents and bad routing. So you don’t get the full autonomous experience. But as I tell my MBA students, a good model does not have to be perfect. Finally, households were not randomly selected and the sample is small.

Nonetheless, Joan and coauthors wanted to get a ballpark estimate of what happens to VMTs if you take the pressure of having to drive yourself out of the equation. The results are, frankly, shocking.

They tracked travel patterns the week before having a chauffeur, during the chauffeur week and the week after. Here’s what they learned:

  • Overall Vehicle Miles Travelled (VMT) increased by 83% for the sample! This is almost a doubling. The range of driving increases were 4% for a millennial and 341% (!) for a retiree!
  • Everyone in the sample sent the car off without them at least once (to escort family/friends or run errands), which was responsible for a third of the induced VMT. Two thirds of those miles were trips with only the chauffeur (picking up unicorn lattes?).
  • The usage patterns shifted to more trips (a 60% increase in trips), more travel in the evening (90% increase) and taking longer trips (90% increase in trips longer than 20 miles). This makes sense since seniors state that they dislike driving in the dark. Also, if I did not have to drive myself, I would go to Tahoe each weekend!
  • The impact on walking went two ways. One third of subjects decreased their walking and the other two thirds of subjects increased their walking.
  • There was significant heterogeneity across cohorts. Seniors don’t drive much, and little in the evening. You give them a car, and wine country – here I come!

So what do I take away from this study? Firstly, Joan Walker and her lab are awesome. Second, we should do more of this, with a larger more representative sample. This is a handful of households who are not representative (they were bay area households and we are definitely not representative in good and annoying ways). Third, we should let households have the chauffeur for a month or two, so we can see whether this is just pent up demand, or a true change in behavior. Fourth, I would like to see this done in urban and suburban settings across countries. Do this in Europe, the US and China to begin with.

So how can this be done? Money for the Walker Lab! Research is expensive, but this is a first order problem that we do need good answers to. If overall VMT double with this technology, when planning models only assume that VMT change with incomes and gas prices, we are setting up transportation infrastructure all wrong. Further, if we make driving less painful, people may choose to live further from where they work, which would increase VMT even more! I would also be interested to see what happens if you get a chauffeur versus an Uber/Lyft. In one model you own the car. In the other you don’t, but have to wait for an uncertain amount of time for your car to arrive and cannot choose exactly what car you get. Seems like an experiment these large ridesharing services should be interested in. At UC, we’re here to help! Give us a call!

Keep up with Energy Institute blogs, research, and events on Twitter @energyathaas.

Suggested citation: Auffhammer, Maximilian. “_V_astly _M_ore _T_ravel.” Energy Institute Blog, UC Berkeley, March 4, 2019,

Maximilian Auffhammer View All

Maximilian Auffhammer is the George Pardee Professor of International Sustainable Development at the University of California Berkeley. His fields of expertise are environmental and energy economics, with a specific focus on the impacts and regulation of climate change and air pollution.

10 thoughts on “_V_astly _M_ore _T_ravel Leave a comment

  1. Our new Car Wash WordPress themegot approved on Themeforest before few weeks.A car (or automobile) is a wheeled motor vehicle used for transportation. Most definitions of car say they run primarily on roads, seat one to eight people, have four tires, and mainly transport people rather than goods. Cars came into global use during the 20th century, and developed economies depend on them. and also your site very good .

  2. I can confirm – my interest in taking far away weekend trips is directly proportional to whether I am driving or a friend is driving.

  3. Introducing marginal cost pricing should mitigate such a large bump in VMT.

    Future transport subscription services will likely have pricing systems that will have non-zero prices per trip which will encourage users to think about the marginal costs of each trip. Also, the sooner a mileage or VMT tax (and congestion pricing!) is introduced the more likely that even the private autonomous vehicle owners will make their marginal costs salient and thus mitigate their VMT.

  4. As one who trashed your earlier post, I’m pleased you’re coming to your senses on this. Now you’re on the right track, i.e. convenience => consumption.

  5. Interesting article, Max. Perhaps the bump in VMT is due in part to the knowledge that it’s a one-time offer for a limited time period. Like when I buy a rare wine at Costco knowing it it won’t last long and they probably won’t get it again. Perhaps you and Joan can figure out a way to test/correct for this potential error. Give the test subject a chauffeured car for a lifetime? (Sign me up!)

  6. Yes, it would be interesting to try this experiment in a city with good public transport, like London.

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