The potential of governmental regulation on shared mobility-on-demand systems

Shared Mobility-on-Demand services have the potential to contribute to a more socially and environmentally sustainable mobility provision. However, this potential may not be fully exploited due to possible conflicts with the objectives of the service providers. Thus, political discourses address regulatory instruments to influence providers’ operational planning. This paper analyzes the effects of two currently debated instruments, i.e., the introduction of a minimum pooling rate and a minimum spatial acceptance rate. Our analysis is based on mathematical optimization models that we formulate as generalizations of the selective dial-a-ride problem. More precisely, the problem is first captured by a single-period model formulation and then generalized to a multi-period horizon to implement different regulatory strategies. In a comprehensive computational study, we solve the regulated model formulations to optimality both for artificial and real-world data provided by our industry partner FLEXIBUS. We evaluate different levels of regulation for both instruments regarding their feasibility and their impact on the Shared Mobility-on-Demand system, and thereby discuss key factors, specific issues, and recommendations with regards to the practical application of regulatory instruments for public authorities that can be derived from the results of our study. Overall, our analysis recommends a multi-period application for both regulatory instruments. In this context, a moderate minimum pooling rate can enhance environmental sustainability, though it may create trade-offs with social or service provider objectives. In contrast, a minimum spatial acceptance rate shows minimal conflicts with other objectives, but requires an effective spatial partitioning approach and is sensitive to the provider’s supply–demand ratio.