Entropy-maximizing methods of transport analysis vis-á-vis a physical system theory modeling framework

The entropy-maximizing method suggested by Wilson for the development of the gravity model of transportation system is examined from the physical system theory point of view. Whereas Wilson's entropy maximizing approach considers the transportation system in the aggregate as a single entity, in order to develop an expression for the “system entropy,” the physical system theory modeling framework as well as the systemic entropy-maximizing method discussed invoke the component-to-system construct to formulate the requisite expression for the “system entropy.” It is seen that both the physical system theory method as well as the systemic entropy-maximizing method are endowed with a certain intuitively appealing and operationally viable property. This property has the desirable effect of enabling any of the various relevant forms of the system-level model to be developed by hypothesizing suitable relationships among the flow-volume and level-of-service variables of the constituent transport links (viewed as components of the transport system) in a manner which is both consistent in the network theoretic sense as well as commensurate with the system model in the behavioral form. This feature provides the motivation for attempting a systemic interpretation of Wilson's entropy-maximizing method, in the context of a few elementary conceptual configurations of a transport network, to gain useful insights for a relative comparison of entropy-maximizing methods on one hand and systemic methods on the other.