Navigation apps such as Google Maps and TomTom help millions of drivers every day choose the fastest or most efficient route to their destination. But what impact do they have on cities when they are used simultaneously by thousands of vehicles?
A study published in Nature Communications provides an answer. The research was conducted by Giuliano Cornacchia, Mirco Nanni and Luca Pappalardo of the Institute of Information Science and Technologies of the Italian National Research Council (CNR-ISTI), and Dino Pedreschi of the University of Pisa.
The findings show that ldepar.
“Using computer-based traffic simulations, the study analysed the impact of navigation systems on traffic in Florence, Milan and Rome, combining GPS data from private vehicles with route recommendations provided by major navigation services, including Google Maps, TomTom, Bing Maps and Mapbox,” explains Luca Pappalardo, Senior Researcher at CNR-ISTI, Associate Professor at the Scuola Normale Superiore and coordinator of the study. “The simulations allowed us to analyse different scenarios by varying traffic levels and the adoption rate of satellite navigation systems: from 0%, when no vehicles follow the directions provided by a navigation service, to 100%, when all vehicles are guided by one. In the study, we assessed the effects on route diversity and CO₂ emissions in each city.”
“The aim of the study is not to establish whether navigation systems are inherently beneficial or harmful,” adds Giuliano Cornacchia, first author of the study. “These tools can benefit individual drivers, but when large numbers of users receive similar route recommendations, they can produce unintended collective effects on urban mobility.”
The findings indicate that as the adoption rate increases, route diversity decreases significantly, with vehicles tending to be channelled onto an increasingly narrow set of roads. In full-adoption scenarios, route diversity decreases by up to 14% compared with the scenario in which route recommendations are not followed. The adoption of navigation systems also tends to redirect traffic towards motorways and major arterial roads.
The study also shows that the environmental impact of navigation systems is multifaceted: the benefits depend primarily on traffic levels and adoption rates. “Under light traffic conditions, navigation systems reduce CO₂ emissions. Under heavy traffic conditions, however, benefits are observed at low adoption rates. Once a certain threshold is exceeded—varying according to the service and the city and generally ranging between 60% and 80%—the benefits diminish, disappear or may even be reversed, as observed in some of the scenarios simulated in Rome,” explains Dino Pedreschi, Professor in the Department of Computer Science at the University of Pisa.
The research contributes to a broader debate on the impact of algorithms and artificial intelligence systems on society. “Studying how artificial intelligence and algorithms influence individual choices and, through them, our society is one of the central themes of both our laboratory’s research and our City-AI Coevolution project, funded by the Italian Ministry of University and Research (MUR) through the FIS funding programme,” says Pappalardo. “Navigation systems are an everyday example of algorithms that shape individual decisions—in this case, which road to take—but when adopted on a large scale, they can affect the collective behaviour of an entire city.”
The future challenge, the authors conclude, will be to design navigation services capable not only of optimising routes for individual users, but also of taking into account the overall effects of their recommendations on the city.
