Public transport systems are central to the economic and social functioning of modern cities, yet they are increasingly challenged by congestion phenomena that deteriorate service quality in terms of speed, crowding, and reliability. A growing body of research has sought to understand these dynamics, highlighting the welfare and efficiency implications of user delays, uncertainty, and discomfort (e.g., de Palma et al., 2017, Coulombel & Monchambert, 2023). At the same time, investments in mass transit systems such as metro, light rail, or bus rapid transit have broader implications that extend beyond the system itself: they affect travel demand across competing modes (Liu & Li, 2020, Gu et al., 2020), shape the spatial structure of cities, and influence patterns of accessibility and inequality reduction (e.g., Glaeser, Kahn & Rappaport, 2008; González-Navarro & Turner, 2018). These questions are not only of academic importance but also highly relevant for sustainable mobility policies and the
reduction of urban inequalities. Within this project, the doctoral candidate will have the opportunity to address research questions in either of these (or both) two subfields—public transport congestion or the urban and distributive impacts of mass transit expansion —depending on their interests and data availability