| A shipment scheduling and operational control method is developed and tested, to help railroads become more competitive for high revenue, service sensitive freight. A bid-price based, profit maximizing revenue management approach is proposed to allow a rail carrier to develop achievable and market sensitive quotations of delivery time far new shipments calling in. Bid prices are derived using a subgradient step size algorithm; a modified shortest path procedure is used to solve the decomposed subproblems.; Once the service quotation has been developed, a deterministic, cost minimizing, multicommodity network flow model, including train capacity and integral flow constraints is solved to manage shipments moving on the railroad in real time. This model dynamically reroutes shipments to take advantage of all available train capacity in the network, while still meeting the committed delivery times on priority shipments. A customized dual ascent procedure, using a tabu search approach as an anti-cycling mechanism, adapts the previous solution any time new information is received.; Both procedures have been integrated into a rolling horizon simulation model. Simulation results indicate up to a 10 point improvement in railway operating ratio may be achievable through implementation of this shipment management strategy. |
