Alternate Capacity Reliability Measures for Transportation Networks

This article explores the use of capacity reliability measures for transportation networks. The authors define capacity reliability as the probability that the network capacity can accommodate a certain volume of traffic demand at a required service level. Capacity is used to assess the adequacy of a degradable transportation network. The authors modify the standard capacity reliability measure by allowing a non-uniform growth in the spatial distribution of the origin-demand (O-D) pattern. The authors next develop two network capacity models related to the concepts of ultimate capacity and practical capacity. The article provides numerical results from the analysis of these three capacity reliability measures. The authors conclude that the two alternate capacity models not only allowed a non-uniform O-D growth in the spatial distribution of the O-D demand patterns but also corrected the underestimated biased problem in the reserve capacity model. In addition, the alternative models provided a higher behavioral richness in modeling the interaction between network capacity and level of service of a road network (with consideration of zonal development).