Sensitivity of the traffic flows in transportation networks

Obtaining the equilibrium flows in transportation networks based on optimizing users' cost is one of the important problems in urban transportation planning. Therefore, finding accurate equilibrium flows in a short time is a significant issue. The required time to solve the traffic equilibrium problem and the accuracy of the obtained results depend on the information level about the transportation system. Using more detail increases the cost of data collection and, dimensions of the problem and, therefore, creates difficulties in solving it. Certainly, a detail level of data should be proportional to the accuracy level that is required. Collecting additional data does not necessarily improve the accuracy level of the results and may only increase the design costs. In this paper, the sensitivity analysis of the equilibrium flows in traffic assignment models with respect to changes in some important transportation network attributes is considered. These attributes include: the accuracy level in measuring link specifications (e.g., width), diversity of travel time functions, intersection delay functions, the method of connecting the zone centroids to a transportation network and number of traffic zones.