Scheduling operations at system choke points with sequence-dependent delays and processing times

Transportation service facilities often form system choke points with service rendered to entities from multiple queues that require staging for processing. With an MIP model that accommodates sequence-dependent setup times and processing times, we demonstrate how scheduling can be improved relative to simple rules that impose equity (such as FIFO) or efficiency (such as fastest processing time). Using an efficient heuristic scheduler for problems of this type, we then demonstrate, with simulation, the benefits that can occur from employing the refined scheduling procedure at a series of choke points in a transportation system subject to highly variable seasonal traffic.

► We blend optimization and simulation to analyze a system with convergent queues.
► A heuristic that considers the two-stage queueing structure improves performance.
► Efficiency is achieved while fostering equity.