Effects of the Plan Vélo I and II on vehicular flow in Paris -- An Empirical Analysis

TL;DR

This study quantifies how Paris's Plan Vélo I and II reshaped car traffic by applying the Network Fundamental Diagram (NFD) with a re-sampling approach to loop-detector data from 2010 and 2023 across two zones with different intervention intensities. It maps detectors to lane-kilometres using OpenStreetMap data and normalizes measurements to derive per-lane metrics, enabling estimation of network capacity, critical density, and free-flow speed. Results show substantial drops in capacity and free-flow speed, especially in the central Zone 1, but overall congestion did not increase, implying a shift toward cycling and other modes. The findings support the effectiveness of large-scale cycling infrastructure as a demand-management tool, while highlighting the need for complementary strategies to further reduce car travel and improve mobility equity.

Abstract

In recent years, Paris, France, transformed its transportation infrastructure, marked by a notable reallocation of space away from cars to active modes of transportation. Key initiatives driving this transformation included Plan Vélo I and II, during which the city created over 1,000 kilometres 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 re-configuration on the network-wide traffic flow. Using the Network Fundamental Diagram (NFD) and a re-sampling 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, capacity declined by 34%, with a 40% reduction in free-flow speed. While these changes seem substantial, the NFDs show that overall congestion did not increase, indicating a modal shift to other modes of transport and hence presumably more sustainable urban mobility.

Figures (8)

• Figure 1: Paris map and its Arrondissements
• Figure 2: Matching loop detectors to the Higher-Order Road Network of OpenStreetMap
• Figure 3: "Pistes cyclable"
• Figure 4: "Bande cyclable"
• Figure 5: "Autre itinéraires cyclables"