A journey across the multiple scales of human mobility
Aleix Bassolas (Supervisors: José Javier Ramasco and Maxime Lenormand)
PhD Thesis (2019)
Human mobility is prevalent across all spatiotemporal scales and has been a main subject of study on account of its influence in the transportation infrastructures, the environment and the spread of pathogens. Yet for many years now
the lack of detailed data has hindered its systematic study. Thanks to the digital revolution and the rise of emergent technologies occurred during the XXI century, the era of data scarcity came to an end and we avail of human activity data at an unprecedented level of detail. This thesis provides a physics approach to the study of the multiple spatiotemporal scales human mobility, from the worldwide to the urban scale, proving the potential of its tools to investigate beyond traditional topics. Throughout this work, we combine the analysis of Information and Communication Technologies data with the use and development of new metrics and models to better understand the mechanisms governing it.
We start by studying the worldwide scale of tourism through the use of data from online social networks with geolocated information and provide a mathematical method to quantify the relevance of touristic sites. Additionally, we also provide a glimpse of how our methodology could be used to investigate the presence of visitors in touristic environments. Nonetheless, it is not only important to measure and quantify human mobility, but also to model it. Detailed data might not be always available and, thus, the development of models to unveil the laws behind human movement and the variables governing it is crucial. On account of the growing number of models developed over the last years, we perform a comparison of the most widely used ones focusing on commuting trips.
The prevalent increase of urban population and the challenges emerging therein compel us to focus on the intra-urban scale, where the study of human mobility has a lot to say. We first unveil the hierarchical structure of cities by developing a metric solely based on mobility. Thereafter, we show that our metric is connected to the transportation, environment and health in cities. In fact, transportation policies progressively became a topic of major concern due to the increase of congestion and emission of pollutants. Hence, we develop a model that mimics the movement of individuals through the public transportation system and allows us to study the delays produced by massive events such as concerts, demonstrations or sports matches. By solving our model analytically and performing simulations, we prove that the dimension of the public transportation network is the major driver of the scaling of delays and disruptions. In addition to a more efficient transportation management, many cities have implemented toll policies. Therefore, in the final chapter of this thesis, we use a traffic simulation toll and a demand generated from ICT data to evaluate the consequences of the implementation of a toll policy around the city of Barcelona.