Modelling Rail Carrier Assignment and Relocation in Multimodal Pod System

A multimodal pod system features modular autonomous vehicles consisting of detachable transport units mounted on mode-specific carriers. Within this system, transport units arriving at the railway network need to be assigned to available rail carriers to continue their journey. For better alignment between carrier availability and transport demand, rail carriers are allowed to relocate empty within the network. This work presents a mathematical optimisation model for the associated rail carrier assignment and relocation problem. The model's performance is demonstrated using a small case study, which highlights the impact of the number of rail carriers and their initial distribution in the railway network on the number of handled transport units and total relocation time. Specifically, increasing the number of rail carriers from two to three resulted in an average of 1.25 additional transport units to be assigned, with an average 55% increase in relocation time. Furthermore, varying the initial distributions of rail carriers lead to difference of up to transport units assigned,
while relocation times varied by as much as 120% of the average relocation time. To enable a more general assessment, future work will apply the model to a larger and more realistic case study.