城市高架路下匝道地面联接段最小长度模型

Minimum-length-requirement model for expressway off-ramp joint

为了提高下匝道地面联结段的系统通行能力,提出了一种计算联结段长度的方法.给出了地面联结段的基本定义及假设,分析了地面联结段构造特性及交通流特性.采用临界安全间隙理论、概率论及运动学方法,综合考虑车辆驶离匝道后汇入地面道路、完成交织运行和顺利驶入下游交叉口左转车道的运行过程,从系统的角度构建下匝道地面联结段的最小长度模型.对于新建道路,根据模型计算可确定联结段的最小长度;对于现有道路,将实测值与模型计算值进行比较,可分析地面联结段产生拥堵原因,便于采取有针对性的改善措施.最后结合实测调查数据,通过与CORSIM仿真模型的输出值进行比较,对模型的正确性进行了验证,结果表明模型是有效的.

To augment the capacity of off-ramp joint, a method to calculate its length is presented. With the definition and basic hypothesis of off-ramp joint, the characteristic of its structure and traffic flow are analyzed. From a systematic viewpoint, kinematics, gap-acceptance theory and probability theory are employed to establish the minimum-length-requirement model for expressway offramp joint. While modeling, the more difficult traffic maneuver of running off the off-ramp road, finishing its interweaving and running onto the left-turn lane of downstream intersection are taken into consideration comprehensively. For a newly constructed road, the required minimum length can be computed using the model. For an existing road, based on the comparison of the measured value and calculated value, the model is helpful for finding out the reasons of congestion on the off-ramp joint, and taking corresponding improvement measures. Finally, the model is verified to be feasible through comparison with the simulation results of CORSIM （corridor simulation model）.