苜蓿叶立交集散车道连续入出口最小间距研究

长安大学公路学院,陕西西安710064

交通工程;苜蓿叶立交;集散车道;连续入出口;交织;最小间距;VisSim仿真

Minimum spacing of continuous entrance and exit on the collector-distributor road of alfalfa leaf interchange
PAN Binghong,LIU Juan,CHAI Hu,LI Xiang,and ZHANG Ranyang

School of Highway, Chang’an University, Xi’an 710064, Shaanxi Province, P. R. China

traffic engineering; alfalfa leaf interchange; collector-distributor road; continuous entrance and exit;weaving; minimum spacing; VisSim simulation

DOI: 10.3724/SP.J.1249.2022.03305

备注

《公路路线设计规范》(JTGD20—2017)中对互通式立体交叉同侧入口与下游出口(简称连续入出口)之间的间距尚未规定,当连续入出口距离较小时,交织车流相互影响,不仅降低通行能力,还会影响区域交通安全.本研究选择苜蓿叶立交主线设置集散车道的情况,通过分析此区域车辆运行特性,确定连续入出口最小间距的计算模型.根据《公路通行能力手册》确定交织类型与交织区车辆速度等关键参数,计算出交织区长度与饱和度,并对交织区长度和服务水平进行检验,提出苜蓿叶立交集散车道连续入出口最小间距推荐值.利用VisSim软件构建连续入出口路段的交通仿真模型,以冲突率为安全性评价指标,对不同设计速度组合下最小间距推荐值的仿真冲突率进行评价.结果表明,推荐的入出口最小间距安全水平为安全、较安全和临界安全,故间距推荐值合理.研究成果可为苜蓿叶立交集散车道的连续入出口设计提供参考,完善相关规范与设计细则.
The spacing between the same side of entrance and downstream exit (continuous entrance and exit) of the interchange has not yet specified in the highway route design specification (JTG D20—2017). When the spacing is small, the interweaved traffic flow affects each other, which not only reduces the traffic capacity, but also affects the traffic safety. In this paper, the collector-distributor road is set in the main line of alfalfa leaf interchange. By analyzing the operation characteristics of vehicles in this area, we obtain the calculation model of minimum spacing of continuous entrance and exit, and determine the key parameters such as the weaving type and the vehicle speed of the weaving area according to 'China Highway Capacity Manual'. Then we calculate the length and saturation of weaving area and examine the length and service level of weaving area. Finally we propose the recommended minimum spacing of continuous entrance and exit of alfalfa leaf interchange. We use the VisSim software to build the traffic simulation model of continuous entrance and exit section, take the conflict rate as the safety evaluation index, and evaluate the simulation conflict rate of the recommended minimum spacing under different design speed combinations. The evaluation results show that the safety levels of the recommended minimum spacing of entrance and exit are safe, relatively safe or criticality safe, indicating that the recommended spacing is reasonable. The research results can provide a reference for the design of continuous entrance and exit on the collector-distributor road of alfalfa leaf interchange, and help to improve the revelent specifications and design rules.
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