In Journal of Royal Society Interface 13:116 (March 2016).
Knowing how individuals move between their places is fundamental to advance our understanding of human mobility (González et al. 2008), improve our urban infrastructure (Prato, 2009) and drive the development of transportation systems. Current route choice models that are used in transportation planning are based on the widely accepted assumption that people follow the minimum cost path (Wardrop 1952), despite little empirical support. Fine-grained location traces collected by smart devices give us today an unprecedented opportunity to learn how citizens organize their travel plans into a set of routes, and how similar behavior patterns emerge among distinct individual choices. Here we study 92,419 anonymized GPS trajectories describing the movement of personal cars over an 18-month period. We group user trips by origin-destination and we find that most drivers use a small number of routes for their routine journeys, and tend to have a preferred route for frequent trips. In contrast with the cost minimization assumption, we also find that a significant fraction of drivers’ routes are not optimal. We present a spatial probability distribution that bounds the route selection space within a ellipse, having the origin and the destination as focal points, characterized by high-eccentricity independent of the scale. While individual routing choices are not captured by path optimization, their spatial bounds are similar, even for trips performed by distinct individuals and at various scales. These basic discoveries can inform realistic route choice models that are not based on optimization, having an impact on several applications, such as infrastructure planning, routing recommendation systems and new mobility solutions.