Scheduling shared passenger and freight transport on a fixed infrastructure

• New approach for integrating freight in fixed-infrastructure public transit. • Linear mixed-integer program for aperiodic timetabling and freight allocation. • Simulation-based evaluation of two different operational modes. • Computational sensitivity-analysis towards demand changes. Increases in last-mile transport contribute to congestion and pollution in urban environments. To make deliveries more sustainable, they may be integrated with existing public transport infrastructure, e.g., metros or trams. This integration can rely on alternative operational modes: shared infrastructure lets passenger and cargo vehicles share the same rail network, whereas shared vehicles simultaneously transport cargo and passengers. To explore the effects of integrated planning under different operational modes, we introduce a linear mixed-integer program that optimises the train schedule and allocates cargo. It features a lexicographical objective function that prioritises passenger transport while minimising cargo delivery delay. We analyse the interplay of operational modes, scheduling solutions, and demand settings in a simulation study.The results show that a well-planned train schedule significantly contributes to service quality and reduces the system’s sensitivity to increasing freight demand. Furthermore, a system with shared vehicles is more robust towards fluctuating demand, whereas a system with only shared infrastructure is a valid option to allow a high dwell time for freight vehicles.