Simulation of Local Sustainable Transportation Policy with Mobility Innovation by comparison with Japanese and French Cities

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Résumé:

[The purpose of research]
The aim of this paper is to elucidate the interdependent development cycle regarding sustainable transport policy and mobility innovation in local authorities, focusing on the contribution of mobility innovation to sustainable local transport, including the reduction of CO2 and Air pollutants emissions from vehicles.
Our research employs a simulation-based approach to evaluate how the introduction of LRT, BRT or Electric Vehicle in Japanese cities could contribute to sustainable urban development, based on the empirical outcomes observed in France. To achieve this, we collect and analyze extensive data from French cities that have adopted LRT, BRT or Electric Vehicle systems and experienced significant environmental benefits. These datasets include indicators such as modal shift patterns, traffic congestion reduction, carbon and air pollution emissions decline. By utilizing this data as a reference, we construct a model that simulates the integration of LRT, BRT or Electric Vehicle into target Japanese cities and measures the prospective improvements in transportation efficiency, environmental impact.
The study investigates the impact of introducing Innovative public transit systems (with a focus on LRT, BRT or Electric Vehicle for public service) on urban environmental sustainability. We combine transport demand modeling with longitudinal statistical data to compare outcomes before and after LRT or BRT implementation in the French case cities. The objectives are twofold:
1. Quantitatively assess how LRT or BRT introduction affected key indicators of sustainable urban development in the French cases.
2. Identify counterpart Japanese cities—based on comparable population size, geographic context, and economic profile—to simulate the potential benefits of similar public transportation investments in Japan.
By establishing these comparisons, the research aims to isolate the causal relationships between LRT-based mobility (including BRT-based style) interventions and urban environmental sustainability outcomes. This approach allows us to project how analogous measures could address mobility challenges from a public perspective in Japanese cities.

[Methodology]
We employ a transport demand modeling framework calibrated with real-world data from the French cities. This includes modal split statistics, traffic counts, transit ridership, emissions inventories (CO2 and Air pollutants). Statistical analyses (difference-in-differences and time-series comparisons) are used to control external factors and identify the specific contribution of LRT (or BRT) projects to observe changes. Key metrics analyzed include:
• Car Usage Reduction – decline in private vehicle trips and congestion levels;
• CO₂ and Air pollutants Emissions – changes in transport sector greenhouse gas and air pollutants emissions;
These metrics align with broader policy goals of decarbonization and sustainable growth. Data from French “LRT cities” or “BRT cities” inform a simulation model to predict impacts if comparable Japanese cities implement LRT under similar conditions.

[Practical implication]
Our analysis of French LRT introductions reveals clear patterns of mobility and sustainability benefits. All studied cities saw a significant modal shift away from car use toward public transit after LRT launch. This means that those cities have succeeded in reducing CO2 and air pollutants from vehicles.
A comparative analysis allows us to extrapolate these findings to Japan, where medium-sized cities face similar mobility and environmental pressures. The study identifies several Japanese cities with comparable profiles (in terms of population scale and car-reliant urban form) that lack robust rail transit systems. By inputting their data into the calibrated model, we simulate the projected outcomes of implementing LRT in these cities. Preliminary simulations suggest that Japanese cities could expect analogous benefits: significant drops in car usage and emissions of CO₂ and air pollutants. These insights are especially relevant for policymakers and urban planners in Japan’s regional centers, as they highlight a viable path toward mobility innovation that aligns with national decarbonization targets and improving air pollution.
Crucially, the research underscores the importance of supportive social and regulatory frameworks. The French experiences were facilitated by policies such as dedicated funding for public transport, pedestrianization schemes, and integrated land-use planning – indicating that regulatory context can enable or hinder the success of such projects. For Japan, this implies that achieving similar outcomes will require not only building the infrastructure but also adopting complementary policies (e.g. incentives to discourage excessive car use, transit-oriented development regulations, and community engagement in planning).

[Conclusion]
This study contributes to the conference theme of mobility issues from a public perspective by providing evidence-based analysis of how investing in sustainable transport infrastructure can yield broad societal benefits. The comparative approach (French case studies and Japanese simulations) offers a unique perspective on the transferability of best practices in urban mobility. The findings have significant implications for shaping policy decisions: they demonstrate that introducing LRT systems can be a powerful tool for cities striving to reduce carbon emissions while fostering sustainable economic growth. Urban planners and regulators can leverage these insights to craft integrated transport and land-use strategies that prioritize public transit, thereby improving urban livability and resilience.