The Perfect Selfishness of Mapping Apps
Apps like Waze, Google Maps, and Apple Maps may make traffic conditions worse in some areas, new research suggests.
By ALEXIS C. MADRIGAL
Mar 15 2018
What is the price of anarchy?
Technically, in transportation engineering, the price of anarchy describes the difference between what happens when every driver selfishly picks the fastest route and what the socially optimal traffic outcome would be.
In the pre-mobile-app days, drivers’ selfishness was limited by their knowledge of the road network. In those conditions, both simulation and real-world experience showed that most people stuck to the freeways and arterial roads. Sure, there were always people who knew the crazy, back-road route, but the bulk of people just stuck to the routes that transportation planners had designated as the preferred way to get from A to B.
Now, however, a new information layer is destroying the nudging infrastructure that traffic planners built into cities. Commuters armed with mobile mapping apps, route-following Lyft and Uber drivers, and software-optimized truckers can all act with a more perfect selfishness.
In some happy universe, this would lead to socially optimal outcomes, too. But a new body of research at the University of California’s Institute of Transportation Studies suggests that the reality is far more complicated. In some scenarios, traffic-beating apps might work for an individual, but make congestion worse overall. And autonomous vehicles, touted as an answer to traffic-y streets, could deepen the problem.
“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.