Integrated drayage scheduling problem with stochastic container packing and unpacking times

Abstract

This paper considers the integrated drayage scheduling problem. Two new models are developed that account for the uncertainty of (un)packing times in drayage operation without an explicit assumption about their probability distributions. These models are developed for situations when an accurate probability distribution is not available. The first model requires the specification of the mean and variance of the (un)packing times, and the second model requires the specification of mean and upper and lower bounds of the (un)packing times. To demonstrate the feasibility of the developed models, they are tested on problem instances with real-life characteristics. The numerical results show that the drayage operation time increases when the mean of (un)packing times, the variance of the (un)packing times or the user-specified confidence level is increased. Also, the results indicate that the stochastic models produce schedules that are more likely to be feasible under a variety of scenarios compared to the deterministic model.

Keywords:

• Drayage scheduling problem
• empty container allocation problem
• vehicle routing problem
• intermodal freight transport
• stochastic optimization