快速路晴雨天环境运行特征差异及最佳服务流率

Differences in Expressway Traffic Characteristics and Optimal Service Flow Rate on Sunny and Rainy Days

摘要:

城市快速路雨天较晴天通行缓慢、拥堵频发，通过对比雨天、晴天环境下快速路运行特征，揭示晴雨环境下服务流率与车速的动态关系，是城市快速路智能化动态管理的首要问题，为此研究快速路晴雨天环境下的最佳服务流率分析方法。首先，利用线圈检测数据分析雨天和晴天环境下流率、速度、占有率的分布特征，采用K-S检验证实了晴雨天交通流存在显著差异；分别对雨天和晴天进行通行能力及运行失效分析，结果显示按现行规范标准确定的饱和度（V/C）并不适用于雨天交通流服务水平分析，存在侧重强调最大通过量而对发生交通失效后表达不准确的局限性。鉴于此，提出兼顾一定运行车速且最大化服务交通量的方法，给出最佳服务流率的概念及其确定方法。建立综合流量—速度—占有率的3维K-Means聚类模型，得到雨天、晴天运行失效前后的交通状态聚类结果，阐释了运行失效前后的服务流率与服务水平关系，指出运行失效前稳定流率可以作为最佳服务流率。

Abstract:

This paper investigates the analysis method of the optimal service flow rate of the expressway on sunny and rainy days. First， the distribution characteristics of flow， speed， and occupancy rate on rainy and sunny days are analyzed using coil loop data. Then， the K-S test is used to confirm the significant difference in traffic flow on sunny and rainy days. The capacity and the bottleneck breakdown analyses are performed on rainy and sunny days， respectively. It is shown that the V/C calculated according to the current standard does not apply to the analysis of the level of service （LOS） of rainy-day traffic flow， and there is a limitation in emphasizing the maximum throughput and inaccurate information after the bottleneck breakdown. Therefore， this paper proposes an academic idea of maximizing the service traffic volume while taking into account a certain operating speed and provides the concept of optimal service flow rate and its determination method. It， then， establishes a three-dimensional K-means clustering model with integrated flow-speed-occupy to obtain the traffic state clustering results before and after breakdown on rainy and sunny days. The results explain the relationship between service flow rate and LOS before and after breakdown， and point out that the pre-queue transition flow can be used as the optimal service flow rate.