Optimising mode choice in a bi-modal freight network considering sustainability and urban logistic stakeholder perspectives

In the last decade, Germany’s courier, express, and parcel industry has seen its consignment volume double to 4 billion annually, primarily moved by fossil-fuel-powered road vehicles. This growth increases urban congestion and emissions, highlighting the need for sustainable alternatives like rail transport to meet climate and emission goals.

This study examines optimal, sustainable mode choice in bi-modal freight networks. Specifically, we introduce inner-city hubs that enable transshipment between road and rail modes to allow more freight shifting to rail. Using a network flow model, we minimise transport costs by assigning each consignment to either trains or lorries, while assessing the influence of transport policies like high-speed freight trains, road tolls, and subsidies on the modal split. Additionally, we incorporate the objectives of city logistics stakeholders. A sensitivity analysis examines the German parcel network’s response to variations in costs, demand, velocity, emissions, and rail capacity.

Our results suggest that rail transport can be a viable alternative to road in numerous scenarios. For example, a slight increase in lorry operation costs initiates a shift to rail, while city taxes exceeding 200 cost units for lorries leads to a shift towards rail transport. Train network capacity is a critical factor in determining modal choice, with policy and stakeholder decisions also influencing mode shifts.

The proposed network flow model provides a robust framework for evaluating the impact of predefined freight policies on mode choice in parcel delivery networks, showing conditions under which rail freight can be integrated into a sustainable inner-city logistics supply.