A process systems approach for detailed rail planning and scheduling applications

Value chain integration is an ongoing challenge: while computing power has improved, there is little modeling consistency across the system. This paper bridges this gap by proposing a novel formulation for train scheduling, a linking element of value chains, using the Unit-Operation-Port-State Superstructure (UOPSS). Train scheduling is a challenging problem: rail lines can be hundreds of kilometers long with train crossing strategies that are based on a train station level, while also requiring results with a minute-time scale resolution. In mixed-use rail systems with limited passing loop infrastructure, trains have different passing priorities and lengths, thus differing in their ability to use passing loops. The proposed model is the basis of the Hatch Rail Optimizer (HRO) software. In addition to small case studies, the power of HRO is demonstrated through a practical case study involving a 370 km rail corridor with five different train sizes over a week-long scheduling horizon.