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The biggest drawback of driverless cars

Driverless cars could save thousands of lives. They might also break our cities.

Driverless cars have the potential to substantially reduce the death toll from likely the most dangerous everyday activity in American life: driving. So it might surprise you to know that the very people who are working to make transportation safer, more pleasant, and more humane are actually pretty divided on them.

That is because if driverless cars ever become pervasive enough on American roads to make a dent in the US’s sky-high car fatality rate, they are also likely to bring greater transformations to the form of our cities, towns, and arteries that connect them that are not all positive. Many experts believe that autonomous vehicles (AVs) will eventually make car travel so cheap and convenient that they’ll greatly increase overall car use in the US, which, as Vox contributor David Zipper pointed out last year, would likely cause more traffic jams and make the country feel even more car-dominated than it does now.

A new meta-analysis of research on that subject puts additional numbers to these projections. Incorporating evidence from 26 studies on AVs’ impacts on the flow of car traffic, University of Texas-Arlington researchers Farah Naz and Stephen Mattingly find that a future where driverless cars become widespread is likely to increase the total number of miles traveled by vehicles in the US by around 5.95 percent. The number could be a bit lower if AVs are shared (as with a rideshare model, for example, like Waymo) and would be higher if they were largely owned by individuals or households, like most cars are today.

This added mileage is a bigger deal than you might think, because even small percentage increases in miles driven can contribute to traffic congestion in a non-linear manner, with just several extra cars (even with impeccably rational AV “drivers”) having the capacity to turn a mild slowdown into stop-and-go........

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