城市快速路车流运行状态安全性评价

Safety evaluation of urban expressway traffic flow operation status

为了对城市快速路的车流运行状况进行评价,提出基于数据包络分析(DEA)的车流运行状态安全性评价方法,并对该方法的工程实用性进行研究。深入分析反映交通流稳定性的交通指标,将道路交通状态指标划分为基础性指标和特征性指标2种类型。以交通量、速度和密度等基础性指标为输入指标,以速度标准差系数、车辆变道率和平均车头时距等特征指标为非期望输出指标,运用线性转化将非期望指标转化为期望指标;基于数据包络分析理论构建城市快速路车流运行状态评价模型,通过计算不同路段输入和输出指标之间的差异性,可以得到多个评价样本路段之间的相对安全性;最后,以西安市绕城高速为例,分别选取4个交织路段和6个正常路段作为评估对象,使用雷达测速枪和视频法进行交通调查,并借助LINGO11.0软件对模型进行求解,验证了模型的实用性。研究结果表明:10个评价样本路段中,6个路段为有效决策单元,道路安全度达到了相对有效,4个路段为非有效决策单元,存在潜在的安全隐患,其中非有效决策单元绕城高速A、B、C、J路段的道路相对安全度分别为97%、88%、98%和96%;在交通量、平均行驶速度或车流密度等输入指标发生突变时,道路交通安全隐患存在被放大的可能性,容易发生交通事故。

To evaluate the traffic safety of driving on urban expressway, a method based on data envelopment analysis(DEA) was proposed to evaluate the safety of traffic flow. In addition, the practicability of the evaluation method was verified. Some indexes which can reflect the stability of traffic flow were analyzed deeply. The traffic stability indexes were divided into the fundamental indexes and the characteristic indexes. The fundamental indexes represented by traffic flow, velocity and density, were selected as the input indexes. The coefficients of speed standard deviation, the rate of lane changing and the average of the headway, were selected as the output indexes. Then the non-expected indexes were converted to the expected indexes by using linear transformation. The undesired output indexes were converted to the desire output indexes according to linear transformation. Based on EDA method, the model of the traffic safety evaluation on urban expressway was established. The difference of input and output indexes in every evaluation segment were calculated, so the relative safety of multiple evaluation samples could be obtained through the model. Take 10 segments of the Xi’an Ring Expressway including 4 weaving segments as example. The radar speed gun and video methods were used to collect traffic data. The LINGO11.0 software was used to solve this model. The results show that there are 6 segments, which are effective units and the road safety degree is relatively effective, while 4 segments are ineffective units with potential safety hazards. The relative safety degree of road sections A, B, C and J of the ineffective units are 97%, 88%, 98% and 96% respectively. Based on the analysis of the evaluation results, it is proposed that when the input indexes such as traffic flow, velocity or traffic density change such as increasing, the hidden danger of road traffic safety is likely to be magnified and traffic accidents are likely to occur. 3 tabs, 3 figs, 33 refs.