Integrated Transportation Network Design Optimization

Traditionally, the design of a transportation system has focused on one of the two systems that comprise the transportation architecture, the vehicle or the network design. However, to define a systems level architecture for a transportation system, it is necessary to expand the system definition during the design process to include the network definition, the vehicle architecture, and the operations, which couple the vehicle and the network. In this paper, the transportation architecture is decomposed into these fundamental sub-systems by classifying the decisions required to define each sub-system. Utilizing the integrated transportation system formulation, the design of the transportation architecture can be obtained by concurrently optimizing the vehicle and network decisions. By formulating the problem in this manner, the optimization can exploit the coupling between the vehicle and network definition to find a system-level solution that best satisfies the system objective. The case study presented in this paper focuses on the design of an aircraft transportation network for overnight package delivery. By concurrently optimizing both the vehicle and network definition for a selected few cities with a fixed demand, we obtain a minimum of a ten percent improvement in cost over that obtained by optimizing the network design using a set of pre-defined aircrafts. Additionally, by comparing the concurrently optimized solutions with the solutions obtained by traditional vehicle optimization, a minimum of an eleven percent improvement in cost is realized. The improvement in system cost obtained by the integrated transportation optimization implementation can be attributed to the reduction in operational inefficiencies for the transportation system.