高速公路前置指路标志设置距离及其安全影响

为弥补我国现行规范和美国MUTCD2009关于高速公路前置指路标志设置距离经验主义的缺陷,首先分析了驾驶员驶离主线驾驶行为及前置指路标志设置距离的影响因素.车道数、车道宽度、车道变换时间、驾驶员的视觉特性、标志牌的架设方式以及主线和匝道上的运行速度对出口匝道安全性有显著影响.介绍了前置指路标志的3种架设方式,即路边直立式、路上横跨数和中央架设式,并给出了各自的适用条件.然后建模计算了不同道路几何条件和交通条件下各安装方式的设置距离,3种安装方式具有相同的模型结构.最后以路上横跨式为例,TSIS-CORSIM模拟结果表明,所给模型计算的设置距离在分流鼻上游500m范围内产生的车道变换数较少,比我国的现行规范少58.93%,比MUTCD推荐值少27.35%,因而具有更好的安全性能.

Placement distance of freeway exit advance guide sign and its safety impacts

To remedy the empirical pitfalls of current chinese specifications and MUTCD 2009 guidelines in determining the placement distance of freeway exit advance guide signs,the driving maneuver of exiting traffic is analyzed and the factors influencing placement distance are explored.Variables including the number of lanes,lane width,lane-changing time,driver＇s visual characteristics,sign installation methods and operating speeds on both freeway mainlines and exit ramps are found significant in explaining exit safety.Three different installation methods,namely ground installation,overhead installation and median installation,are introduced and their applicable conditions are given.Models,with the same structure among the three installation methods,are developed to compute the placement distance under different roadway geometric and traffic conditions.Taking overhead installation as an example,simulation results in TSIS-CORSIM show that the proposed distance reduces the number of lane changes in the area from the ramp nose to 500 m upstream by 58.93% compared with current Chinese specifications and 27.35% compared with MUTCD 2009 guidelines.Thus,the distances recommended in this paper have a better safety performance.