基于冲突概率的无信号控制T形交叉口安全评价

为了更合理地评价无信号控制 T 形交叉口的安全水平,研究在交叉口类型划分的基础上,提出1种以交通冲突数的概率分布为评价指标的安全评价方法。其中,交通冲突数的均值和分布分别采用广义线形模型和泊松分布描述,在广义线形模型中,交通冲突数的均值为被解释变量,冲突交通流的交通量为解释变量,根据交通冲突数的均值估算,计算交通冲突数的泊松分布的概率。在利用实测数据对广义线形模型的参数进行标定后,根据主路直行与非直行交通流量之间的差异性,进一步提出了简化模型,将主路直行交通的影响简化为影响系数,并根据流量不同划分为4个等级,通过分析交通冲突数的概率计算值与安全阈值数的概率临界值之间的关系,进行无信号控制 T 形交叉口的安全评价。最后通过实际案例,对模型的可操作性和准确性进行了检验。研究表明,非直行流向流量较直行交通流量对交叉口安全水平的影响更大,利用文中所提出的简化模型,可重点调查其它流向流量,而主路直行交通流量只需观测其流量大致范围即可,平均工作效率提升25%。 

A Safety Evaluation Model for Unsignalized T-Intersections Based on Conflict Probability

In order to evaluating the safety of the unsignalized T-intersections in a more objective way,this paper proposes a safety evaluation method after providing a detailed classification of intersections.The probability of traffic con-flicts is used as the evaluation index.In this paper,the average of traffic conflicts and its probability are described using a generalized linear model and Poisson distribution.In the generalized linear model,the average of the traffic conflicts is used as the explained variable while the conflict traffic flow rate as an explanatory variable.The traffic conflict probability of Poisson distribution is estimated based on the estimated average of conflict traffic.A simplified model is developed after the model parameters are calibrated based on the survey data.The effect of the through movements on main-street is sim-plified by an impact factor,which is divided into 4 levels based on the volumes.By analyzing the relationship between the calculated value of traffic conflict probability and the critical value of safety probability threshold,the safety of the unsign-alized T-intersections is evaluated.The feasibility and accuracy of the model is validated through actual cases.The results show that the traffic volumes of the turning movements have a greater effect on the safety than through movements.The study concludes that the volume of turning movements should be more carefully investigated than the volume of the through movements on main-road when using the proposed simplified model.The efficiency can be improved by 25% in average.