부산대학교 도서관

Sag sections are segments of the expressway where the slope changes greatly from downward to upward. In the expressway networks, sag sections are usually the bottleneck of trafc. Sag sections have become an important inducement of trafc congestion for its special geometric characteristics. However, the intrinsic mechanism of trafc congestion on sag sections is still unclear, especially the congestion in the tunnels. To describe the trafc fow of diferent road conditions, a dynamic optimal velocity function is proposed. Then, coupled with the proposed function, a new lattice hydrodynamic model is developed to reveal the infuence of sag on the stability of trafc fow in the tunnel. The linear stability condition is further obtained to analyze the potential efects of sag on the dynamics of trafc fow. The modifed Korteweg-de Vrie (mKdV) equation is also derived by using perturbation theory, and the corresponding kink-antikink soliton solution is obtained. Finally, the evolution process of trafc fow during the sag section is demonstrated by numerical simulation. It is suggested that the downhill section sag worse the stability of trafc fow, while the uphill section could stabilize the trafc fow, which is consistent with the theoretical analysis well. In addition, we also study the evolution laws of density waves under diferent disturbances in the metastable region.