Capacity of Dual-Right-Turn Lanes at Signalized Intersections under Mixed Traffic Conditions

To explore the potential capacity of dual-fight-turn lanes at signalized intersections under mixed traffic conditions, we defined two conflict zones between right turn vehicles and through bicycle corresponding to different right turn flows from dual-right-turn lanes. Relationships between the arrival rate of bicycle group at each conflict zone and the saturation flow rate of right turn movement were investigated. A model based on gap acceptance theory was adopted to estimate the capacity of dual-right-turn lanes under mixed traffic conditions. An analysis was carried out using the collected data from three four-leg signalized intersections in Beijing, China, where the dual-right-turn lanes were used. In addition, we also discussed the patterns of bicycle lane in the urban area of Beijing, and classified it based on its characteristics in use. It is concluded that the two lanes of dual-fight-turn lanes produce different capacities under mixed traffic conditions, and the analysis on scenarios of dual-right-turn movement traversing bicycle traffic plays a key role in explaining the different capacity performance of the two right turn lanes. Error analysis of the model indicated that the model was rational.

Effect of Transit Capacity onto Morning Commute Problem with Competitive Modes and Distributed Demand

A lane exclusively for transit is one measure to reduce urban congestion and intelligent transportation systems (ITSs) are expected to make this policy more effective. However, the advantage may be limited if a transit agency does not provide sufficient vehicles. This study evaluates the effect of transit capacity on a dedicated transit lane policy by examining the morning commute problem, by defining user equilibrium and system optimisation considering transit capacity. It was confirmed that reduced transit capacity under user equilibrium smoothly increases the transit cost per person, which decreases the duration period of the dedicated transit lane and increases the number of early and delayed car commuters. However, the effect of reducing transit capacity under a system optimum depends on the initial solution of the system optimum.

Enhancing Urban Mobility: Exploring the Potential of Exclusive Motorcycle Lane Using VISSIM

The proliferation of Mobility on Demand (MOD) services has ushered in a surge of ridesharing platforms, catalyzing the emergence of micro mobility solutions like motorcycle sharing. Consequently, motorcycles have witnessed unprecedented growth over recent decades. This proliferation, while offering convenience, has introduced challenges such as diminished road capacity, and compromised safety. This study advocates for the implementation of exclusive motorcycle lanes to mitigate the ensuing disorderliness using VISSIM microsimulation platform. Empirical data from a key corridor in Dhaka is harnessed to calibrate and simulate network performance scenarios—pre- and post-implementation of dedicated motorcycle lanes. The outcomes of our simulation experiments exhibit the implementation of dedicated motorcycle lanes leads to a reduction in vehicular throughput but improvement the flow of motorcycles. In addition, Surrogate Safety Measures (SSMs) demonstrate the safety improvements through implementation of the treatment.

Designing Right-Turn Vehicle Box as a Supplemental Treatment to Eliminate Conflicts with Pedestrians and Bicycles

Field observations illustrated that, right-turn vehicles stopped at various positions when proceeding within the right-turn lanes, while some of them trespassed on the crosswalks with multiple stops. In this case, pedestrians and bikes (ped/bike) are encountered unsmooth and hazardous crossings when right-turn vehicles encroaching their lanes. Meanwhile, this also causes conflicts between right-turn and through vehicles at the crossing street. To better protect ped/bike at crossings with right-turn vehicles, this paper proposes a concept of “right-turn vehicle box” (RTVB) as a supplemental treatment within right-turn lanes. Sight distance, geometric conditions, and behaviors of vehicles and ped/bike are key factors to consider so as to set up the criteria and to design the suitable treatment. A case study was conducted at an intersection pair in Houston, USA to shape the idea of RTVB, together with driving simulator tests under relevant scenarios. The preliminary crosscheck examination shows that the right-turn vehicle box could possibly provide ped/ bike with smoother and safer crossings. In the interim, the safety and efficiency of right-turn operations were also improved. To further validate the effects, implementation studies should be conducted before the RTVB can make its debut in practice. Future works will focus on the complete warrants and design details of this treatment. Moreover, the concept of “vehicle box” could also be transplanted to other places where turning movement(s) needs assistance or improvements.

网联混合流高速公路车道管理及通行能力分析

为提高网联混合交通流环境下高速公路基本路段通行能力,需针对车流量、网联自动驾驶车辆(CAV)比例制定与之匹配的车道管理策略。针对低CAV比例环境下CAV专用车道闲置浪费的问题,提出了一种CAV优先车道管理策略。利用跟驰模型推导了混合交通流基本图模型,构建了人工驾驶车辆(HV)专用车道、CAV专用车道、混行车道及CAV优先车道通行能力模型,分析了高速公路不同车道组合方案适用的交通需求范围。然后,以双向4车道高速公路为例,基于SUMO仿真平台分析了CAV优先车道性能,对不同车道组合方案的通行能力和适用范围进行了仿真验证,并从效率、安全及能耗角度对车道组合方案进行了比较。结果表明:在适用性方面,CAV比例p≤0.5时,两条混行车道适用的交通需求范围最大,CAV优先车道次之,CAV专用车道最小;在效率方面,p≤0.5时,设置CAV专用车道方案的效率最差,CAV优先车道表现较好,且p越小优先车道效率提升越显著;在安全、能耗方面,设置CAV专用车道方案的能耗和安全性能较佳,CAV优先车道次之;在p>0.5时,设置CAV专用车道方案的综合表现更优;在多种车道管理方案均可行时,相比于两条混行车道方案,采取其他车道管理措施在安全、能耗上的表现均有提升;在需求D≤2500 veh/h,p≤0.5时,相比于其他车道方案,采用CAV优先车道方案既能满足通行需求、降低能耗,也能更充分地利用道路资源,综合表现均衡。

左转专用短车道信号交叉口通行能力分析

针对信号交叉口左转专用短车道排队阻塞导致的时空资源浪费、通行能力降低等问题,本文分析排队阻塞车流形成与消散过程,从车流到达分布理论和概率论2个角度建立了排队阻塞概率模型。考虑到不同流向的放行顺序,结合交通流波动理论,建立了3种不同相位方案下排队阻塞时进口道通行能力模型。通过VISSIM对模型进行检验,并对模型影响因素进行敏感性分析,观察不同影响因素下通行能力变化趋势。结果表明,模型能更加准确地计算不同信号控制条件下左转专用短车道通行能力;左转专用短车道下,短车道容量、信号周期、绿信比、车流比例、车流平均到达率对通行能力起主要影响。

非机动车道混合流通行能力计算及特性分析

针对非机动车交错行驶、蛇形运动特点,为更合理计算非机动车道混合流通行能力,提出了一种基于时空消耗的非机动车道混合流通行能力计算方法。通过武汉市7条非机动车道的饱和时段交通流观测数据,采用本文方法计算该7条非机动车道的混合流通行能力;利用数据拟合与方差分析得到不同隔离方式及宽度下非机动车车速及电动自行车比例对单一非机动车平均时空消耗的影响,进而分析非机动车道的混合流通行能力特性。实例研究结果表明:纯电动自行车比纯人力自行车的单一非机动车平均时空消耗约降低2.15 (m2·s)/辆,电动自行车的运行效率高于人力自行车,对通行能力具有提升作用。基于时空消耗的混合非机动车道通行能力计算分析,能克服忽略非机动车行驶特性及多因素简化降低非机动车道混合流通行能力计算精度的弊端,计算原理清晰,便于路上试验开展。

Coordinated optimization of signal timing for intersections with dynamic shared through-and right-turn lanes

Through and right-turn shared lanes are widely designed to increase the capacity of through traffic,but they can also cause delays for right-turn vehicles.This study presents a dynamic control method for a shared lane that prioritizes right-turn vehicles at the beginning of the cycle and subsequently allows through traffic to queue in the shared lane for saturated discharge.The traffic wave model is employed to reveal the dynamics of the traffic flow under this control and to derive the relationships among major traffic parameters.Constrained by the major relationship,a linear programming approach to minimize the total queue length is developed to determine the proper values of control parameters,including the shared area length,subordinate signal time lag,and shared or exclusive duration.A sensitivity analysis of the control parameters for different arrival rates and flow ratios is performed.Comparisons are conducted among the dynamic shared lane,the fixed exclusive lane,and the fixed shared lane.The results show that the dynamic control method results in a lower delay for both through and total traffic.

城市快速路社会车借用公交专用道行为影响分析

应用微观仿真实验,以社会车车道疏导交通能力变化为观测目标,以社会车流量大小及借道通行车辆比例为观测变量,实现社会车借用公交专用道行为的量化影响分析.借鉴已有成果标定微观仿真模型参数而后开展仿真实验,分析得出借道车辆在当前稽查管理模式下能提升车辆自身通行效益,但对群体效益带来负面影响,且随着借道车辆数的增加车辆自身通行效益也在降低,对群体带来更为不利的通行影响.研究结果可为强化公交专用道资源管理提供理论基础.

中运量公交专用道功能复合提升规划研究

为构建高品质、高效益的中运量干线公交,解决上海市中运量公共交通在实施运营中存在的客流效益较低、对社会车辆影响大等痛点问题,依托北横中运量公交工程的规划研究,首先,基于中运量公交专用道的研究概况及运行现状,分析规划建设同时具有公交客流效益高、可衔接轨道交通促进两网融合并对区域常规公交体系有整合优化作用的多功能复合中运量公交专用道的必要性;其次,基于规划工程的实践,提出相应的规划实施策略,如合理统筹公交及私人机动车路权,融合沿线道路、公交、慢行设施空间设置集约横断面方案,整合沿线常规公交、衔接轨道交通的两网融合运营模式等策略方法,以提升片区及通道的整体交通功能;最后,对其提升效果进行评估。本文旨在为中运量公交专用道的相关研究提供参考。

A case study on multi-lane roundabouts under congestion:Comparing software capacity and delay estimates with field data

Existing studies on modern roundabouts performance are mostly based on data fron： singe lane roundabouts that are not heavily congested. For planners and designers interested in building multilane roundabouts for intersections with potential growth i~ future traffic, there has been a lack of existing studies with field data that provide reference values in terms of capacity and delay measurements. With the intent of providing such reference values, a case study was conducted by using the East DowlinC Road Roundabouts in Anchorage, Alaska, which are currently operating with extensive queues during the evening peak hours. This research used multiple video camcorders t（ capture vehicle turning movements at the roundabouts as well as the progressior~ of vehicle queues at the roundabout entrance approaches. With these video records, the number of vehicles in the queues can be accurately counted in any single minute during the peak hours. This study shows that unbalanced entrance flow patterns （i.e., ~ne entrance has significant higher flow than others） can intensify the queue and delay fo., the overall roundabouts. Then various software packages including RODEL, SIDRA and VISSIM were used to estimate several performance measurements, such as capacity. queue length, and delay, compared with the collected field data. With the comparison, it is found that all the three software packages overestimate multi-lane roundabout ca pacity before calibration. With default parameters, SIDRA and VISSIM tend to underes timate delays and queue lengths for the multi-lane roundabouts under congestion, while RODEL results in higher delay and queue length estimations at most of the entrance approaches.

高速公路加速车道上车辆的汇入模型

为了揭示高速公路合流区加速车道上车辆的运行规律 ,利用摄像机等观测仪器对中国许多省市高速公路合流区匝道车辆的汇入特征数据进行了大量调查。在对大量调查数据进行分析处理的基础上运用微分法建立了匝道车辆的汇入模型和行驶距离模型。该模型不但解释了调查结果 ,而且对高速公路规划设计。

短车道对信号交叉口通行能力影响研究

针对交叉口进口道拓宽后形成的短车道,由于其长度的限制,存在因车辆排队溢出而造成阻塞的问题,结合交通流理论和概率论的相关成果,从定性分析和定量计算两方面研究了短车道排队阻塞对信号交叉口通行能力的影响。针对3种不同的信号相位方案,建立了考虑短车道潜在排队阻塞情况下的车道组通行能力计算模型,并通过仿真对模型进行了检验。在此基础上,进行了短车道条件下相关因素对信号交叉口通行能力影响的敏感性分析。研究发现在交叉口进口道存有短车道条件下,短车道长度、信号相位方案对通行能力起主要影响;同时对通行能力而言,存在最佳信号周期。

高速公路加速车道上车辆的汇入特征分析

为了研究高速公路入口匝道上车辆的汇入规律 ,利用摄像机和Autoscope 2 0 0 4图像处理系统在江苏、山西、河北、北京、天津、广东等地对高速公路合流区加速车道上车辆的汇入特征数据进行了大量调查 .在对调查数据进行处理分析的基础上 ,运用概率分析和微分法建立了匝道车辆的汇入概率模型和行驶距离分布概率模型 ,利用实际数据对模型进行检验 ,并举例说明模型在高速公路加速车道长度的设计、评价和分析方面的应用 .该模型揭示了匝道车辆汇入概率与合流区几何特征、交通特征的数学关系 ,不但解释了调查结果 ,而且对高速公路规划设计、控制管理等工程实践有重要的指导意义 .

关于高架快速路车道宽度设置的探讨

由于高架快速路在设计速度、车辆组成和服务功能等方面都与高速公路和一般的城市道路有很大的不同,因此其车道宽度的设置也应有别于其他的道路。通过分析在上海高架路上采集的大量实测数据,应用数理统计的方法建立了速度和流量之间的关系模型,进而得到了不同车道宽度对应的通行能力值。在保证车辆安全行驶和不降低通行能力的前提下,推荐出高架快速路的最小车道宽度值,以节约土地资源,降低工程造价。

五叉环形交叉口信号协调控制模型

对五叉环形交叉口的信号控制方法进行了研究,给出了基于环道容量约束的信号控制参数优化的模型,模型着重考虑了两个因素:环道容量约束,进口道灯、环道灯相互之间的绿信号协调、红信号协调。利用本文提出的控制模型设计了一个实例的信号控制方案,并通过V ISS IM仿真评价了该信号控制方案,验证了本文提出的控制方法的有效性。

基于行为分析的道路通行能力中车道数因素研究(英文)

运用实证调研和行为分析方法,通过对北京和上海的典型路段进行观测,研究道路的车道数与平均每车道通行能力的关系,结果表明在不受干扰的快速路基本路段上,道路的平均每车道通行能力随车道数的增加而边际递减。进一步基于驾驶员的驾驶行为分析得出,车辆换道行为的增加及其导致的车辆间相互干扰的增大是造成通行能力递减的主要原因。这一研究表明以后的道路规划设计中不能忽略车道数对平均每车道通行能力的影响,对完善道路通行能力手册的编制,道路网络的规划设计有着重要的理论意义和实践指导作用。

短车道信号控制交叉口通行能力概率模型

针对短车道信号控制交叉口,提出考虑不同流向相互阻塞概率的通行能力计算模型,该模型克服了以往交叉口通行能力计算模型中对交叉口短车道影响考虑不足的缺陷.根据短车道条件下不同交通流的相互阻塞特征,将交叉口短车道分为三类.基于车流到达随机性,考虑相邻周期排队状态的相互作用,将阻塞过程划分为不阻塞、可能阻塞、阻塞后三个阶段,建立了通行能力计算模型.基于实测数据标定后的微观仿真分析表明,相对于HCM(Highway CapacityManual)模型,该模型计算结果能够相对更真实地反映短车道信号控制交叉口通行能力.针对短车道长度、短车道数目,绿信比和周期长度的参数敏感性分析,进一步揭示了在不同流量水平下短车道对交叉口通行能力的影响.

城市道路两相位交叉口左转车道通行能力研究

以无信号控制交叉口可插车间隙理论为基础,分析了常见城市道路两相位信号控制交叉口左转车的交通流特性,建立了左转车道通行能力计算模型,通过实例对模型中的参数进行了标定。运用Vissim 3.6仿真软件对实际交叉口交通环境进行模拟,得到单位时间允许左转车通过交叉口进口道的最大车辆数,与模型计算所得通行能力值相比较,两者相对误差小于10%,从而证明所建立模型具有较强的适用性。

基于元胞自动机交通流模型的车辆换道规则

将元胞自动机模型应用于周期性边界条件下的高速公路交通的换道规则模拟,并对不同条件下交通流的平均速度和流量进行仿真。基于驾驶员的性格差异,提出了更灵活的弹性换道规则,并探讨了不同换道规则对交通流流量等参数的影响。在计算机仿真过程中,通过变换交通流密度,得出了与不同换道规则对应的交通流基本图。结果表明:相对于以前的模型,遵循2种新规则的模型均可不同程度地改善道路的通行能力,提高道路资源的利用效能;从安全性角度进行对比分析,可得出较优的换道规则。