“This problem has been vastly overlooked,” Alexandre Bayen, the director of UC Berkeley’s Institute of Transportation Studies, told me. “It is just the beginning of something that is gonna be much worse.”

Bayen and a team of researchers presented their work earlier this year at the Transportation Research Board’s annual meeting and at the Cal Future conference at Berkeley in May 2017. They’ve also published work examining the negative externalities of high levels of automatic routing.

In the Cal Future talk, Bayen walked through a simulation created in the commercial-transportation simulator Aimsun. The video below shows how the flow of a freeway changes in response to an accident under two conditions: when no drivers use routing apps and when only 20 percent of drivers use routing apps. When there are more app-using drivers, congestion builds up at off-ramps, creating more traffic on the freeway.

“The situation then gets much worse because hundreds of people just like you want to go on the side streets, which were never designed to handle the traffic,” Bayen says. “So, now, in addition to congesting the freeway, you’ve also congested the side streets and the intersections.”

While it’s clear that traffic on local roads gets worse with the use of these apps, Bayen said that nobody has managed to do a multi-scale analysis that can determine if the apps, even if they create local problems, are better or worse for whole traffic basins.

Nonetheless, the adoption and use of these apps continues to grow, too, Bayen said. Over the last 10 years, traffic-routing apps have become a standard accessory for the driving public. According to a 2015 Pew survey, 90 percent of Americans with smartphones use maps for driving directions at least some of the time. As smartphone penetration reaches up above 70 percent, a vast number of people now have access to real-time traffic data on their phones. The driving public is better informed about routes and road conditions than ever before.

In many local neighborhoods, residents have complained about increased traffic volumes. Bayen’s team has been gathering stories from around California of resident complaints and found dozens in even a short time window, as shown in the map below.

Bayen’s team showed that their concerns are real. In the chart below from a 2016 presentation, drivers who are routed by mapping applications spend many more minutes on “low-capacity roads,” which is to say side streets.

But the Berkeley research suggests there could be a deeper, broader issue. A few people using route-planning maps makes things better, but a lot of people using them might force a deterioration of driving conditions. It is a very 2018 version of Garrett Hardin’s “tragedy of the commons,” where we, ourselves, are the cattle, the mapping software is the herdsman, and the roads are the common pasture. Nonetheless, the outcome is the same. In transportation-engineering terms, it could be that routing apps increase the price of anarchy.