In the last 10 years, the volume of consignments in the courier, ex-press and parcel service industry in Germany has doubled to 4 billion consignments per year. These consignments are mainly transported by fossil fuelled road transport. The increased volume is causing ris-ing strain on city infrastructures and has gained public and research relevance. Considering main objectives of urban logistics stakeholders a potential shift to rail in order to reduce congestion and emissions needs to be explored [1].

In this research, we investigate the problem of optimal sustainable mode choice in bi-modal freight networks. It introduces a concept of inner-city hubs, which enable transhipment between small electric vehicles for distribution and long-distance road and rail transport. A network flow model is developed which minimises induced costs by deciding preferred mode between the inner-city hubs. Transport poli-cies such as high-speed freight trains, tolls or reducing energy con-sumption are implemented [2]. Different objectives of city logistic stakeholders are considered, such as carriers which aim to minimise transport costs or inhabitants, which aim to reduce noise and pollu-tion [3].

We demonstrate the model performance on a German parcel net-work and carry out a sensitivity analysis by varying parameters such as velocity, transport costs, emission costs, capacities and a factor which measures the impact on the city. We used public data provided by the German Federal Association of Parcel and Express Logistics and derive the flows of consignments between major German cities [4] and considered different types of artificial logistic networks in Germany like point-to-point or hub-and-spoke.

The proposed model enables evaluating the impact of predefined freight policies on mode choice for parcel delivery networks as well as to which extent and under which conditions rail freight traffic can be integrated into a sustainable inner-city supply chain of the future.