快速路交织区车头时距分布特征

针对快速路交织区中车流的频繁交织行为引发车头时距重分布现象,系统研究了快速路交织区车头时距分布的内在规律,得出了城市快速路交织区内车头时距分布随断面流率动态变化的结论。选择北京、上海、广州等7个典型城市的城市快速路系统为研究对象,利用数理统计方法对采集的代表性快速路中A类交织区中车头时距数据进行分车道分断面统计分析,拟合分析及x~2检验的结果表明断面流率小于250 veh/h时,车头时距服从负指数分布;当断面流率位于250～750 veh/h时,车头时距服从移位负指数分布,而当断面流率位于750～1500 veh/h时,车头时距则服从Cowan M3分布,为城市快速路交织区的通行能力分析、规划管理等方面的深入研究提供了理论依据。

Distribution Characteristics of Headway at Weaving Sections of Urban Expressway

Taking the re-distribution phenomen of headway induced by frequent weaving behavior at weaving sections of urban expressway as research object,the intrinsic rule of automobile headway distribution at expressway was investigated.The conclusion that the distribution of headway varies dynamically with traffic flow rate was obtained.Seven typical cities,such as Beijing,Shanghai,Guangzhou,etc.were chosen as traffic survey areas. The headway data were collected from A-type weaving sections of expressway and then analyzed by statistical, fitting,and x~2 test methods.The results indicate that,headway complies with negative exponential distribution when traffic flow rate is no more than 250 veh/h;while flow rate changes from 250 veh/h to 750 veh/h,it obeys the displaced negative exponential distribution;however,if the flow rate varies from 750 veh/h to 1 500 veh/h,Cowan M3 distribution fits the headway very well.This investigation provides a useful basis for fttrther research on capacity of expressway weaving sections,expressway planning and management.