【作者】 陈振起；

【导师】 毛保华； 张峻屹；

【作者基本信息】 北京交通大学 ， 系统分析与集成， 2009， 博士

【摘要】 大多数发展中国家城市道路交通都具有混合交通特点,混合交通特性导致的一系列问题是发展中国家城市面临的重要交通问题。城市路网中的平面交叉口是混合交通流与混合交通问题最集中的地方之一,对平面交叉口的信号配时与交通组织进行优化在缓解整个路网交通拥堵中具有非常重要的意义。开展这项工作的前提是对交叉口的运行现状进行准确把握和评价,尤其是对交叉口各进口的饱和度和服务水平进行精确计算和评定,这也涉及到交叉口通行能力计算问题。现有信号交叉口通行能力计算方法未能充分考虑混合交通特点,部分研究提出采用简单的折减系数来体现混合交通环境中行人与非机动车的影响,难以兼顾不同交叉口之间的差异,从而可能导致较大误差。有鉴于此,本文以实际调研数据为基础,考虑了不同类型交叉口行人与非机动车对机动车道通行能力影响的差异,包括到对交叉口混合交通环境进行识别、对行人与非机动车干扰的定量分析；通过对混合交通环境下机动车运行特性的分析,构建了可用于不同混行环境的交叉口通行能力计算方法。该方法以混合交通环境下直行机动车的运行模型为基础,即首先对混合交通交叉口直行机动车的运行特性进行分析和建模,其次利用直行机动车运行模型的特定输出指标定量分析了混合交通交叉口的混行程度,提出了交叉口混行级别的定义与划分方法,最后建立了可考虑行人与非机动车实际干扰影响的信号交叉口通行能力计算模型。主要研究内容和结论包括：(1)直行机动车在绿灯初期所受到的干扰分析和在干扰环境下的运行特性分析。对交叉口范围内各类干扰的时空分布特性进行了详细分析,并结合绿灯初期直行车辆加速度的抽样检测数据讨论了直行车辆在交叉口内运行的基本特性。研究表明,交叉口内行人与非机动车对直行机动车的干扰主要发生于三个不同的时间域内和三个独立的小分区上,而且直行车辆在交叉口内运行时表现出一种不同于路段跟驰的中观特性,即致密性行驶队列的形成与消散特性。(2)直行机动车在绿灯初期的运行模型。在致密性行驶队列形成与消散的中观特性基础上,该模型首先将直行车辆在绿灯启亮后最初一段时间内的运行过程划分为四个阶段：初始加速阶段(或致密性队列形成阶段)、致密性队列行驶阶段、队列消散阶段以及自由行驶阶段；其次用不同的运动学方程来刻画各阶段的加速特征,得出了队列中每一辆车在每一个阶段运行的速度—时间曲线；最后,根据跟车时距和运行速度的约束又将相邻阶段联接起来,得到了每一辆车包括各个阶段以及相邻阶段衔接点在内的完整的速度—时间曲线,实现了对致密性行驶队列形成与消散过程的完整刻画。案例分析表明,这种模型在描述绿灯初期直行车辆的运行行为上具有一定的精确度和可靠性,由该模型预测的体现直行车辆运行特征的特定指标值(如直行车辆通过交叉口所使用的时间、通过停车线所使用的时间)与这些指标实际观测值之间的相对误差一般小于1%。(3)交叉口混行程度的定量分析以及交叉口混行级别划分。这部分研究分两步进行：首先,以行人与非机动车流量分布数据为基础对交叉口的混行程度进行初步分析,并在此基础上对交叉口混行级别进行初步划分；其次,针对初步划分中的最低混行级别交叉口确定直行车辆在绿灯初期运行模型的具体形式,并对直行车辆通过交叉口所使用时间进行预测,并将预测值与该指标的实际观测值进行比较,二者之间的差异反映了行人与非机动车干扰对机动车通过交叉口时间的影响。本文通过这种差异对实际交叉口的混行程度进行识别,并实现对交叉口混行级别的详细定义与划分。研究表明,利用与直行车辆通过交叉口所使用时间有关的相对差异指标以及行人与非机动车流量分布指标可将目前实际运行中的混合交通交叉口划分为三个级别：混行程度最低(A)级别、混行程度中等(B)级别以及混行程度最高(C)级别。(4)可考虑行人与非机动车干扰影响及不同混行级别交叉口的直行车道通行能力计算模型。首先,在交叉口混行级别定义与划分的基础上构建了适用于各种混行级别交叉口的通用型直行车辆运行模型；其次,利用所建立模型的特定输出指标对传统停车线法进行改造,构造了一种新的潜在考虑行人与非机动车干扰影响的直行车道通行能力计算方法；最后,运用该方法计算了分属于不同混行级别的实际交叉口的通行能力,并与传统方法进行了比较分析。研究表明,与传统停车线法、《城市道路设计规范》方法相比,由本文方法计算得到的通行能力值最接近实际观测结果(与实测结果之间的相对误差一般在20%以下),也更适合于不同类型交叉口。(5)基于仿真的实证分析。利用仿真软件,将本文构建的通行能力计算方法和传统通行能力计算方法应用于实际混合交通交叉口的通行能力计算,通过仿真软件的运行结果对各种方法的应用效果进行比较分析,并在此基础上实现对本文方法的进一步评价。这种仿真分析与评价的实现途径是：首先根据各种通行能力计算方法得出的通行能力估算值设定可行且变化的流量需求作为仿真输入数据,然后根据仿真输出流量和仿真输出延误随仿真输入变化而变化的规律分析通行能力估算值的合理性,并据此对相应的通行能力计算方法进行评价。仿真评价得出了与理论计算基本一致的结论,进一步验证了本文方法的有效性。更多还原

【Abstract】 Most developing cities are characterized by mixed traffic. Mixed traffic itself always leads to inefficient utilization of network facilities and makes existing methods and models involved in researches on traffic and transportation not so suitable, as they were presented under conditions of pure motorized traffic. The intersection is one of the most significant facilities among the road network in a city, and it is also one of the most prevalent places that pools mixed traffic flows as well as problems induced by mixed traffic flows. Capacity analysis of signalized intersections under conditions of mixed traffic is a difficult but important research subject for developing cities. But existing capacity formulas either ignore effects of disturbances caused by pedestrians and non-motorized vehicles or merely introduce a fixed discount coefficient to meet the effects. Inevitably these formulas will result in big errors when mixed traffic occurs and varies among different intersections. This thesis develops a novel method for capacity analysis and estimation that based on the recognition and discrimination of mixed traffic conditions. It is relied on the analysis of impact of pedestrians and non-motorized vehicles on the advancement of motorized vehicles. Prior to the capacity method, a mathematic model is developed to describe moving features of motorized vehicles under conditions of mixed traffic, and based on the model disturbance effects of pedestrians and non-motorized vehicles are investigated and analyzed. Recognition of disturbance effects makes it possible to distinguish different mixed traffic conditions and this work helps to develop a novel sorting art for signalized intersections which is also presented before the capacity analysis. All works of this thesis are summarized as below:(1) Discussion on the spatio-temporal feature of disturbances caused by pedestrians and non-motorized vehicles at signalized intersections. As the production of the discussion, disturbance time and disturbance zone are defined. The spatio-temporal analysis on disturbances is groundwork in the thesis.(2) Development of a mathematic model (called MASPA model in this thesis) to describe through vehicles advancing during the start part of green time. As green indication starting, through vehicles in the involved approach often experience a particular course observed as that a closely-spaced platoon comes into being and then turns to disperse. The model is based on this course and the movement of each through vehicle is divided into four stages:initially accelerating from rest, shortly after which reducing acceleration rate to join a moving platoon, then increasing acceleration rate to disperse from the platoon and eventually stepping into a free flow. Constraints of time headway and speed are introduced to link adjacent stages. This model produces the velocity-time curve for each through vehicle at each stage and at each junction of adjacent stages. And from the velocity-time curve, two important variables of stop-line passing time and intersection passing time are defined for each vehicle, which are used in the following analysis. Case studies show a good fit for this model to describe moving behavior of through vehicles during the early time of green phase. Especially, for performance measures of stop-line passing time and intersection passing time, the relative error between the empirical value and the estimated value by the model is usually less than 1%.(3) Quantitative analysis on the effect of disturbances derived from pedestrians and non-motorized vehicles. This work leads to discrimination of mixed traffic conditions at signalized intersections and consequently a novel sorting art for signalized intersections. The concept of relative increment (RI) of the through vehicle’s intersection passing time is introduced and calculated by the MASPA model. Here it is confirmed by the technique of traffic survey that the RI of intersection passing time is mainly caused by disturbances of pedestrians and non-motorized vehicles, so the RI is adopted to stand for the effect of disturbances and used to recognize and distinguish different mixed traffic status at different intersections. This part of study makes it clear that according to mixed traffic status (in fact disturbances effect from pedestrians and non-motorized vehicles) signalized intersections in developing cities can be classified into three interweaving grades:the lowest grade (also named grade A), the moderate grade (grade B) and the highest grade (grade C).(4) Development of a novel method for capacity analysis and estimation. This method uses the data of stop-line passing time produced by the MASPA model to found a capacity formula, meanwhile by revising the one of stop-line method which was presented by Beijing Municipal Design Institute, Beijing city, China. In the case study of theoretic calculations at practical intersections, the new method is proved more fit for all kinds of mixed traffic conditions compared to other existed methods.(5) Simulating analysis on the capacity methods. A VISSIM-based simulator is designed to evaluate the capacity method developed in this thesis, comparing with other existed methods. In the simulator varied but feasible motorized flows are preset as the input and the fluctuant outputs of flow and delay are recorded. The analysis and thus the evaluation are derived from the relationship between the output and the input. The result of simulating analysis is quite close to that of theoretic calculations, which confirms the validity of the new method.更多还原