2022 Volume 8 Issue 2 Pages A_300-A_309
In this study, we tried to clarify the factors of speed reduction in non-congested condition and factors that can determine whether or not deceleration waves occur when speed reduction occurs in non-congested condition, targeting areas with frequent congestion on urban expressways. Using continuous trajectory data, we drew contour diagrams and compared the relationship between traffic characteristics and velocity. At the same time, we defined variables related to vehicle platoon characteristics using Time Tailaway and Inter-Vehicular Distance. We also defined deceleration wave states. Next, speed reduction factors were verified by multiple regression analysis, and deceleration waves generation factors were verified by discriminant analysis, considering the time lag.
As a result, it is suggested that left lane utilization ratio increases due to the increase in traffic volume, and when the increase reaches a plateau, speed reduction occurs. At the same time, “Short Time Tailaway Vehicle Ratio” become small and “Short Inter-Vehicular Distance Vehicle Ratio” increases. It is also suggested that the factors that can determine the occurrence of deceleration waves include traffic volume, lane utilization, vehicle platoon characteristics, and lane-changings with large conflicts.
