The growing dominance of cars in suburban areas

Abstract

This study examines the patterns of car dependence in Lisbon and Porto, Portugal’s two largest metropolitan areas, utilising an innovative framework known as the ABC of mobility. This model categorises modes of transport into Active Mobility ($A$), Public Transport ($B$), and Car ($C$). Drawing from census data from 2011 and 2021, we assess the modal choices of commuting adults and students across municipalities. Our findings reveal that central urban areas exhibit a distinct modal distribution, with car use increasing by approximately 1 % for every additional 2 km from the city centre, primarily at the expense of Public Transport usage. In contrast, peripheral areas show significant reliance on cars, with over 75 % of trips made by car, whereas some central zones report car journeys at under 40 %. These results highlight the relationship between urban centrality and modal choice, emphasising the role of Public Transport availability in shaping commuting behaviours.