This paper presents a decentralized merging assistant for mixed traffic situations aiming to increase traffic flow stability around the merging area by minimizing the conflict and limiting the changes in speed. The algorithm encourages early and smooth deceleration of the mainline vehicles upstream of the merging area in order to create gap for ramp vehicle. Simulation results show that the effectiveness of the merging assistant can be different depending on traffic conditions and compositions. A negative side effect that reduces the effectiveness of the proposed algorithm is found and some ideas to solve this problem are discussed.

No abstract

Advanced driver assistance (ADA) systems may change individual driver and vehicle characteristics and influence the overall traffic flow performance. An overview is presented of the relationship between individual driver and vehicle characteristics and platoon and traffic flow stability under manual, ADA, and mixed traffic. The factors that make traffic flow stable or unstable are reviewed and categorized, and how ADA systems influence traffic flow stability is reviewed. The definition of traffic flow stability, assessment methodologies, open issues that need further clarification, and implications for the development of ADA systems are discussed. The result of stability analysis depends not only on driver and vehicle characteristics but also on traffic stream characteristics and the method used to analyze stability.

No abstract

Unlike freeway, urban traffic stream is generally interrupted by signal, and thus observed traffic data may differ from the true (uninterrupted) flow characteristic. This paper deals with the transformation between interrupted and uninterrupted speed on urban road with signalized intersection. Conventional shock wave model and two modified versions of shock wave boundary that address for the unrealistic characteristics of the conventional shock wave are developed. A method of integrating probes and detector data for speed transformation is also discussed. The proposed methods are tested with a virtual isolated signalized intersection by varying the approach demand. The numerical results suggest that all models can significantly reduce the difference between the actual and the estimated uninterrupted (or interrupted) speed compared to the case of no conversion. The applications of the proposed methods including the development of flow-speed model and link travel time estimation are also given. Limitations of the model are explained, and the areas of potential improvement are suggested.