Optimization of multimodal networks including environmental costs: A model and findings for transport policy

In this paper we introduce a modelling approach for the optimization of terminal networks, taking into account the costs of CO2 emissions and economies of terminal scale. The optimization problem is solved by bi-level programming, where the upper level searches for the optimal terminal network configurations by using a genetic algorithm, while the lower level performs multi-commodity flow assignment over a multimodal network.This model is applied to optimize the Dutch container terminal network configuration. The model was calibrated using both the national survey data of freight transport flows by mode and data on throughputs of the Dutch inland container terminals. We find that different efficient terminal network configurations result under different pricing regimes. Also, a reduction in total system costs appears feasible when CO2 emission prices are raised, by taking advantage of previously unexploited economies of scale in the system.