PROPERTIES OF DYNAMIC FREEWAY NETWORK FLEXIBILITY MODEL

摘要

The objective of this study is to investigate the properties of the flexibility model in anetwork of freeways which conveys high volumes of traffic. For that a DynamicSystem Flexibility model was defined and its three major components are evaluatedand discussed. The Dynamic System Flexibility measures and estimates the options ofdrivers traveling between origin–destination pairs (O-Ds) in a freeway network. Thethree models' components depend on the number of possible and feasible routesbetween a given O-D pairs; on the common lengths among the possible routes and, onthe amount of variability between each route's length and the length of the shortestroute. The lengths of the link in the model are perceived lengths and depend on theoccurrence of congestion in them.It was found that the flexibility measure provides a good estimate of thenumber of options available to drivers in a given network. Moreover, this measure issensitive to the amount of congestion in the freeway system, and therefore, the modelthat is proposed is flow-dependent. It was also found that while the common lengthsbetween the routes increase, the flexibility decreases. A pseudo paradox, similar toBraess' paradox, is shown to exist under certain network conditions.