Effectiveness of motorist information systems in reducing traffic congestion

The authors propose a methodology for assessing the systems´ effectiveness in both reducing traffic congestion and examining the interactions among important parameters of the problem, such as the level and amount of information provided, percentage of users with access to information, and congestion levels. The methodology is based on the assumption that provision of information affects the users´ perception on link travel times of a network, and therefore improves their route choice. Preliminary results from an application using a small suburban network show that motorists experience modest reduction in travel times. The gains, however, are proportionally smaller than the ones estimated by other studies. It is suggested that these differences are attributable to the fact that previous studies have ignored interactions among users of the system.<>