Effects of Paris’ Cycling Policies on Vehicular Flow: An Empirical Analysis

In recent years, Paris, France, transformed its transport infrastructure, marked by a notable reallocation of space away from cars to active modes of transport. Key initiatives driving this transformation included Plan Vélo I and II, during which the city created over 1,000 km of new bike paths to encourage cycling. For this, substantial road capacity has been removed from the system. This transformation provides a unique opportunity to investigate the impact of the large-scale network reconfiguration on the network-wide traffic flow. Using the Network Fundamental Diagram (NFD) and a resampling methodology for its estimation, we investigate with empirical loop detector data from 2010 and 2023 the impact on the network’s capacity, critical density, and free-flow speed resulting from these policy interventions. We find that in the urban core with the most policy interventions, per lane capacity decreased by over 50%, accompanied by a 60% drop in free-flow speed. Similarly, in the zone with fewer interventions, per-lane capacity declined by 34%, with a 40% reduction in free-flow speed. While these changes seem substantial, the NFDs show that overall congestion levels did not increase, indicating a modal shift to other modes of transport and therefore presumably more sustainable urban mobility.