Holding decisions for correlated vehicle arrivals at intermodal freight transfer terminals

We propose a vehicle holding method for mitigating the effect of service disruptions on coordinated intermodal freight operations. We extend existing studies mainly by (1) modeling correlations among vehicle arrivals and (2) considering decision risks with a mean-standard deviation optimization model. We prove that the expected value of the total cost in our proposed formulation is not affected by the correlations, while the variance can be miscomputed when arrival correlations are neglected. We also identify some implications of delay propagation when optimizing vehicle holding decisions in real-time. We provide general criteria for determining the boundary of the affected region and length of the numerical search, based on the frequency of information updates. Theoretical analyses are supported by three numerical examples.