An optimal global algorithm for route guidance in advanced traveler information systems

Abstract

Advanced traveler information systems play essential roles in reducing traffic congestion and improving traffic efficiency. In this paper, a global algorithm for the route guidance strategy is proposed in advanced traveler information systems. Compared to the local algorithm, this global algorithm can improve the capacity and efficiency of traffic networks and also counter traffic congestion. The innovative ideas of this algorithm can be viewed mainly from three aspects. First, rather than providing a fixed path between origin and destination, the new algorithm could provide the real-time optimal route guidance information to travelers at every intersection. Moreover, because the route guidance information is based on global traffic information, the optimum global path could also be provided. Lastly, we can use this new global algorithm and apply it to many route guidance strategies. In our study, we first apply it to the congestion coefficient route guidance strategy. The simulation results demonstrate better performances of the global congestion coefficient route guidance strategy compared to that of the local congestion coefficient route guidance strategy. The advantages can be summarized as follow: (1) Critical vehicle occupancy and average flow of saturation state is doubled. (2) Critical vehicle occupancy of meta-stable state and deadlock state are raised by 2.5 times. (3) Vehicle distribution is more homogeneous. We also apply the global algorithm to the travel time route guidance strategy. Even though it brings a slightly lower average flow and a higher origin-destination travel time compared to the global congestion coefficient route guidance strategy, the global travel time route guidance strategy induces a more homogeneous vehicle distribution. Furthermore, we find that the average flow increases when information collection time period decreases, thus information should be updated in a real-time manner in efficient traffic networks.