Range of Applicability of Priority Systems
This report summarized the research conducted at the University of Texas on the performance analysis of priority systems for containers. The performance analysis focused on a selected group of possible priority systems that differ in the extent in which service by priority is implemented. The systems analyzed are: a) base case, i.e., no service differentiation; b) "hot hatch" programs; c) service differentiation at the storage yard; d) service differentiation and the yard gate; and e) combinations of systems b), c), d). The performance analysis was conducted using a simulation system specially designed to simulate priority systems. The performance of these systems is assessed for different combinations of the relevant experimental factors, namely: a) operational scheme, b) proportion of high priority containers, and c) number of incoming containers. Using the resulting performance measures, the impacts on the different segments of users are assessed for each of the systems. In order to gain insights into the applicability of priority systems, i.e. their optimality from the decision maker's standpoint, a formulation was developed to determine under what range of parameters of a choice function a given alternative is optimal. The formulation developed was found to provide useful insights and revealed that all the systems considered have a range of conditions under which they are optimal. Finally, the policy implications are analyzed and conclusions drawn.