Routing and scheduling temporal and heterogeneous freight car traffic on rail networks

Freight car scheduling is taking on a more important role in rail operating plans as more shippers demand trip plan information for their procurement, production and distribution plans, and as railroads pursue operations that are better scheduled and planned. This paper presents several ways to improve current freight car scheduling practices and describes a dynamic freight car routing and scheduling model that can produce more achievable and market-sensitive car schedules. A time-space network representation technique was used to represent car moves on possible sequences of car-to-block and block-to-train assignments on a general-merchandise rail service network. The problem was formulated as a linear multicommodity flow problem; the column generation technique was used as a solution approach. The model was tested on a hypothetical rail network based on the sub-network of a major U.S. railroad.