Optimal design of intermodal mobility networks under uncertainty: Connecting micromobility with mobility-on-demand transit

Mobility-on-Demand Transit (MoDT) is a suitable solution for linking packed urban centers to low-demand suburban areas. Meanwhile, micromobility services, including dockless bikesharing and electric scooters, are growing exponentially worldwide, providing a low-cost, low-emission travel mode for short home-based trips. We propose an intermodal network in which travelers use micromobility for the first-/last-mile connections to MoDT. The optimal design of the intermodal network is formulated as a two-stage stochastic program with a revenue-maximization objective. The first stage solves the near-optimal transfer hub locations, and the second stage considers the integrated operations of the micromobility and MoDT vehicle fleet. This work contributes to the MoD literature by addressing how to coordinate the intermodal transfers and improve the utilization of vehicles with uncertain demand. The movements of these vehicles are modeled as an interconnected closed queueing network with time lags. A new starter-follower model captures the rearranged ride-pooling behavior at these selected transfer hubs. We implement this network design method to evaluate the benefit of combining a bikesharing and a MoDT network in New York City. This paper provides a systematic method for designing intermodal mobility networks, laying the foundation for multimodal mobility applications.