Mobility Inequalities and Urban Poverty: A Decomposition of Travel Speed Differentials in France (2008–2019)

Mobility inequalities are widely analysed using travel patterns, but their drivers remain unclear. Analyses generally rely on individual-based definitions, although transport policies primarily operate through places. We propose travel speed as an indicator of efficiency in overcoming spatial separation. We break down speed gaps using Blinder-Oaxaca decompositions based on instrumental-variable models, drawing on the French National Travel Surveys (2008, 2019) and place- and individual-based definitions of disadvantage. Residents of deprived neighbourhoods travel substantially more slowly, mainly because of compositional factors. They use cars less, rely more on walking and public transport, and travel more often in lower-speed urban environments. Individual-poverty analyses show a marked widening of disparities over time. Car access appears central to modal disparities and their evolution, while gaps and drivers vary across trip-distance bands and urban-unit sizes. Some 2019 results are consistent with the hypothesis of "neighbourhood effects" on mobility. We additionally propose "spatial contraction" as a mechanism whereby slower mobility and modal constraints may restrict disadvantaged populations' access to urban opportunities. Both hypotheses could be examined further. Improving alternatives to car use in deprived areas rather than supporting car ownership appears more sustainable and equitable. Our findings support greater attention to small- and medium-sized urban areas.