PRIORITY-BASED CLASSIFICATION FOR IMPROVING CONNECTION RELIABILITY IN RAILROAD YARDS. PART I OF II: INTEGRATION WITH CAR SCHEDULING

Railroads must be able to provide reliable service with a guaranteed delivery time in order to attract new business and compete with trucking operations. Better control of railroad yard and terminal operations is essential. If available space on a train is sold out, a capability in railyards to ensure connections of railcars needing to move on specific trains becomes essential, so cars with no remaining schedule slack time (where a missed connection would result in a service failure) have first access to remaining train capacity. This two-part paper explores the relationship between priority-based classification and dynamic car scheduling and how railroads can used those methods to improve service and reduce cost. To guarantee connections of cars with no remaining schedule slack time, a sufficient number of low priority cars can be diverted at the hump instead of cherry-picking high priority cars at the trim end of the yard. The process of determining necessary diversions at the hump implements the process of rescheduling cars in excess of train capacity to later trains, or, in the case of dynamic car scheduling, redirecting cars into other classifications to move via a different set of intermediate yards. By combining a scheduled railroad with new dynamic car scheduling and priority-based classification capabilities in yards, highly reliable service can be provided without sacrificing train capacity utilization. Part II of the paper will present procedures for finding a set of train-blocks that can fit into available classification tracks.