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Comparative evaluation of roundabout capacities under heterogeneous traffic conditions

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Journal of Modern Transportation 2015年第4期23卷 310-324页

作者： Ramu Arroju Hari Krishna Gaddam Lakshmi Devi Vanumu K.Ramachandra Rao Department of Civil Engineering IIT Delhi Department of Civil Engineering and Transportation Research and Injury Prevention Programme (TRIPP) IIT Delhi

In heterogeneous traffic conditions, roundabout capacity is described by vehicle and driver characteristics which are different from traffic conditions in homogeneous conditions. In the present study, the capacity of the roundabout is determined using various capacity formulas such as gap acceptance models given by Highway Capacity Manual 2010 （US）, German model （2001）; empirical regression models given by TRRL （UK） and weaving models given by IRC： 65-1976 （India）. In addition, microscopic simulation model like VISSIM （PTV Ger- many） is also used to derive capacity values. Unlike the other capacity estimation models, VISSIM is helpful in estimating capacity values using geometric and driver characteristics and it can also simulate heterogeneous traffic condition accurately. Capacity is estimated after calibrating the simulation model （VISSIM） developed for the roundabout. This is achieved by incorporating different vehicle classes to represent the heterogeneous traffic environment, driver gap acceptance, and lane changeparameters. All the required inputs were extracted from the video using semi-automatic data collection methods. Data are used for the estimation of capacity values from dif- ferent methods mentioned above and for the calibration and validation of simulation model. The capacity values esti- mated form various formulas except German model are distinctly different from the field values and they are either overestimating or underestimating. Analysis of these observations reveals that the capacity values from VISSIM and German models are nearly matching with the field capacity.

关键词： roundabout Capacity VISSIM Simulation Heterogeneous

Calibrating HCM model for roundabout entry capacity under heterogeneous traffic

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Journal of Modern Transportation 2019年第4期27卷 293-305页

作者： Abdullah Ahmad Rajat Rastogi Department of Civil Engineering National Institute of TechnologySrinagarJammu and Kashmir 190006India Department of Civil Engineering Indian Institute of Technology RoorkeeRoorkee 247667India

roundabout is a channelized intersection where traffic moves around a central island,clockwise for leftside driving and anti-clockwise for right-side *** designed roundabouts can handle traffic very smoothly without causing any *** capacity of roundabouts used to be calculated by the weaving theory in ***,calculation of the entry capacity in the recent literature is based on critical gaps and follow-up times,and the Highway Capacity Manual of US(HCM2010)provides an equation to estimate the entry capacity of a roundabout by using the flow in passenger car unit per hour(PCU/h),critical gaps and follow-up times at the entry *** order to examine whether the HCM equation applies to Indian traffic condition or not,we collected data from five roundabouts in India in this *** data were extracted/estimated to calibrate parameters of the HCM *** PCU for a vehicle was estimated on the basis of lagging headway and width of the vehicle,and the critical gap value for a vehicle was estimated by minimizing the sum of absolute difference in a gap with respect to the highest rejected and accepted *** show that the critical gap values obtained under heterogeneous traffic conditions are much lower than those given in the literature for homogeneous traffic *** addition,the modified HCM equation based on the critical gap values was verified using the field data taken during the formation of a continuous and stable queue at the entry of a *** was found that a multiplicative adjustment factor needs to be calculated for different sizes of roundabouts to ensure the adjusted HCM equation represents well the traffic condition prevailing in developing countries like India.A test conducted at another roundabout validated that the entry capacity estimated from the calibrated and adjusted HCM model was consistent with the field entry capacity,and the calibrated and adjusted HCM model could predict the entry cap

关键词： roundabout Entry capacity HCM Heterogeneous traffic Gap acceptance

Guidelines for roundabout circulatory and entry widths based on vehicle dynamics

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Journal of Traffic and Transportation Engineering(English Edition) 2018年第5期5卷 361-371页

作者： Maksym Diachuk Said M.Easa Department of Civil Engineering Ryerson University

Current guidelines for roundabout circulatory roadway width are based on a static method that does not consider circulatory speed. In addition, the roundabout entry width is based on practical experience. This paper presents a method for determining the circulatory and entry widths based on a two-dimensional vehicle dynamics model that involves a system of differential equations of curvilinear motion. The method considers the interactions between a vehicle and road geometric elements, including tire sideslip, vehicle weight, vehicle speed, and vehicle stability. Three design vehicles are considered： intermediate semitrailer （WB-12）, interstate semitrailer （WB-20）, and city transit bus （CITY-BUS）. Design guidelines for the required circulatory width are established for different circulatory speeds （0-60 krrgh） and different inscribed circle diameters （30-80 m）. To simplify the guidelines, for each design vehicle and for each inscribed circle diameter （ICD） the regression model of circulatory roadway width as a power function of circulatory speed was fitted. Guidelines for entry width were also established for typical conditions. The results show the efficiency of the proposed method which provides smaller values of circulatory roadway widths than those of current methods. The difference ranges from 0.4 to 0.6 m for CITY-BUS, 0.7-1.0 m for WB-12, and 1.3-2.0 m for WB-20. The proposed guidelines would be useful in case of spatial restrictions.

关键词： roundabout Circulatory roadway width Vehicle dynamics Inscribed circle diameter

Influence of driver’s yielding behavior on pedestrian-vehicle conflicts at a two-lane roundabout using fuzzy cellular automata

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Journal of Central South University 2022年第1期29卷 346-358页

作者： LI Chuan-yao LIU Shi-kun XU Guang-ming CEN Xue-kai School of Traffic and Transportation Engineering Central South UniversityChangsha 410075China

The roundabouts are widely used in China,some of which have central islands as scenic *** crosswalks connecting to the central islands,normally full of pedestrians,have negative impact on roundabout capability and pedestrian ***,this study proposes a fuzzy cellular automata(FCA)model to explore the safety and efficiency impacts of pedestrian-vehicle conflicts at a two-lane *** reason the decision-making process of individual drivers before crosswalks,membership functions in the fuzzy inference system were calibrated with field data conducted in Changsha,*** specific indicators of efficiency and safety performance,it was shown that circulating vehicles can move smoothly in low traffic flow,but the roundabout system is prone to the traffic congestion if traffic flow reaches to a certain ***,the high yielding rate of drivers has a negative impact on the traffic efficiency but can improve pedestrian ***,a pedestrian restriction measure was deduced for the roundabout crosswalk from the FCA model and national guideline of setting traffic lights.

关键词： roundabout pedestrian-vehicle conflicts fuzzy inference system fuzzy cellular automata model pedestrian restriction measure

roundabout4在肿瘤血管新生及细胞迁移中作用的研究进展

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中华实验眼科杂志 2011年第2期29卷 188-191页

作者：程岩（综述）苏冠方（审校）吉林大学第二医院眼科长春130004

视网膜新生血管性疾病是世界范围内最严重的致盲性眼病之一，包括糖尿病视网膜病变、年龄相关性黄斑变性等。近年来普遍认为血管生长因子是调控视网膜内皮细胞增生和新生血管形成的最主要因素。roundabout 4（Rob04）是近年发现的一种... 详细信息

视网膜新生血管性疾病是世界范围内最严重的致盲性眼病之一，包括糖尿病视网膜病变、年龄相关性黄斑变性等。近年来普遍认为血管生长因子是调控视网膜内皮细胞增生和新生血管形成的最主要因素。roundabout 4（Rob04）是近年发现的一种跨膜蛋白，特异性表达于血管生成活跃的内皮细胞表面。目前的研究认为，Rob04能够调控内皮细胞的迁移及血管新生，参与血管生长因子的信号转导途径，在血管稳定性的调节中发挥重要作用。对Rob04的深入研究将有助于揭示视网膜新生血管性疾病的形成机制。就Rob04的分布、结构、配体及在血管发生、内皮细胞迁移中的作用及与眼部相关的基础研究进行综述。

关键词： roundabout 4 内皮细胞细胞迁移血管生成视网膜神经节细胞

roundabout Performance Analysis Using Connected Vehicle Data

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Journal of Transportation Technologies 2022年第1期12卷 42-58页

作者： Enrique Saldivar-Carranza Jijo K. Mathew Howell Li Darcy M. Bullock Purdue University West Lafayette USA

There are over 8000 roundabouts in the United States. The current techniques for assessing their performance require field counts to provide inputs to analysis or simulation models. These techniques are labor-intensive and do not scale well. This paper presents a methodology to use connected vehicle (CV) trajectory data to estimate delay and level of service for roundabout approaches by adapting the Purdue Probe Diagram used for traffic signal analytics. By linear referencing vehicle trajectories with a particular movement based on the location and time they exit a roundabout, delay can be calculated. The scalability is demonstrated by applying these techniques to assess over 100 roundabouts in Carmel, IN during the weekday afternoon peak period in July 2021. Over 264,000 trajectories and 3,600,000 GPS points were analyzed to rank over 300 roundabout approaches by delay and summarize in Pareto-sorted graphics and maps. The paper concludes by discussing how these techniques can also be used to analyze queue lengths and origin-destination characteristics at roundabouts. The methodology presented in this study can be used by any agency that wants to assess the performance of all roundabouts in their system.

关键词： roundabout Performance Measure Connected Vehicle Big Data

roundabout蛋白家族在膝骨关节炎滑膜中的表达及作用研究

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Roundabout蛋白家族在膝骨关节炎滑膜中的表达及作用研究

作者：王舒厦门大学

学位级别：硕士

研究背景:骨关节炎(Osteoarthritis,OA)又被称为退行性骨关节病,是引起中老年人关节疼痛的常见原因,滑膜炎是其主要的临床病理变化之一。roundabout(Robo)蛋白家族成员包括Robol～4蛋白,是Slit-Robo信号通路中主要的细胞膜表面受体,在... 详细信息

研究背景:骨关节炎(Osteoarthritis,OA)又被称为退行性骨关节病,是引起中老年人关节疼痛的常见原因,滑膜炎是其主要的临床病理变化之一。roundabout(Robo)蛋白家族成员包括Robol～4蛋白,是Slit-Robo信号通路中主要的细胞膜表面受体,在机体细胞增殖、炎症反应及血管增生过程中均发挥重要作用。OA患者滑膜组织表现为滑膜组织增生、炎细胞浸润以及血管增生,涉及多种信号通路的激活,却鲜有Slit-Robo通路在OA滑膜组织中的研究报道。研究目的:探究Robo1～4蛋白在人正常及OA滑膜组织(Synovium,SM)和滑膜成纤维细胞(Synovial fibroblasts,SF)中的表达差异,并通过炎症因子TNF-α、IL-1β及IL-6刺激SF模拟体内炎症环境,探讨Robo1～4蛋白在OA滑膜组织及滑膜成纤维细胞中的表达及作用机制。研究方法:选择膝关节OA需行关节置换术患者的滑膜组织作为实验组(OA组),膝关节韧带、半月板或软骨损伤且滑膜未发生病变、需行关节镜手术治疗者的滑膜组织作为对照组(NC组),运用苏木精-伊红(Hematoxylin-Eosin,HE)染色、蛋白质免疫印迹(Western Blot,WB)实验、免疫组织化学染色(Immunohistochemistry,IHC)、细胞培养及鉴定等实验室技术,对两组滑膜进行组织学和细胞学层面的研究,检测Robo1～4蛋白及相关信号通路的表达情况。研究结果:(1)在术中及关节镜下观察膝关节滑膜组织,OA组较NC组明显增生、肿胀,显微镜下观察滑膜组织的HE染色切片提示OA组较NC组滑膜组织和血管大量增生、炎细胞浸润。(2)用WB、IHC技术对SM中Robo1～4蛋白的表达进行检测,结果表明,与NC组相比,OA组SM中Robo1和Robo4的表达升高,而Robo2和Robo3在SM中的表达很低。用WB和IHC技术对SM中血管内皮生长因子(Vascular endothelial growth factor,VEGF)、非协调性分子5同源蛋白B(Uncoordinated-5-homologB,UNC5B)的表达进行了检测,结果表明OA组SM较NC组VEGF表达升高,UNC5B表达无明显差异。以上结果说明OA组SM中可能存在Robo1/Robo4-VEGF依赖的血管生成。(3)使用细胞培养技术对术中获取的滑膜组织进行原代SF的分离与培养,用短串联重复序列(ShortTandem Repeat,STR)鉴定培养出的原代细胞,结果表明,体外培养出的SF细胞纯度符合下一步实验要求。(4)用WB实验对SF中Robo1～4蛋白的表达进行检测,实验结果显示Robo1～4的表达均很低,OA组与NC组无显著差异,表明OA组SM中升高的Robo1和Robo4可能并非SF所表达。(5)CCK-8细胞增殖实验结果表明,OA组SF细胞增殖活性低于NC组。经TNF-α和IL-1β刺激后OA组SF的增殖活性较NC组明显升高。用Slit2重组蛋白刺激OA组和对照组SF,两组细胞的增殖活性无明显改变。以上结果说明OA滑膜成纤维细胞中可能存在NF-κB信号通路依赖的细胞增殖活性的升高。(6)用WB实验对经TNF-α、IL-1β及IL-6刺激后的OA组SF进行检测,Robo1～4蛋白的表达无明显改变。用TNF-α或IL-1β模拟炎症环境,分别与Slit2共同作用于SF,CCK-8法测细胞增殖实验结果表明,Slit2重组蛋白对SF中TNF-α或IL-1β依赖的细胞增殖无明显影响。以上结果说明在SF中,Slit-Robo信号通路与NF-κB信号通路之间可能无直接调控作用。(7)对OA组和NC组的滑膜组织进行转录组测序分析,共筛选出差异基因3952个,其中2135个基因上调,1817个基因下调,并对差异基因进行了聚类分析。研究结论:OA患者的滑膜组织和血管显著增生,滑膜呈炎症状态,OA滑膜组织中Robo1和Robo4蛋白表达升高,说明OA滑膜组织中可能存在Robo1/4-VEGF介导的血管生成。Robo1～4蛋白在OA滑膜成纤维细胞中的表达无明显升高或降低,说明OA滑膜组织中升高的Robo1和Robo4可能并非滑膜成纤维细胞所表达。OA滑膜成纤维细胞中存在NF-κB信号通路依赖的细胞增殖活性的升高,可能是OA患者滑膜组织增生的原因之一。在滑膜成纤维细胞中,Slit-Robo信号通路与NF-κB信号通路之间可能无直接调控作用。滑膜成纤维细胞中的Slit-Robo信号通路可能不直接参与OA滑膜炎的病理进程。

关键词：骨关节炎滑膜滑膜成纤维细胞 roundabout Robo Slit 滑膜炎

Reconstructing a Six-Leg Intersection into Mohave County’s First roundabout

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Journal of Traffic and Transportation Engineering 2018年第2期6卷 53-60页

作者： Steven P.Latoski Mohave County Public Works P.O.Box 7000KingmanArizona 86402-7000USA

Mohave County,Arizona maintains a six-leg intersection in the Golden Shores area bisected by an uncontrolled regional County highway,County Route 1,where two STOP-controlled section line local roads *** two-lane,rural CR 1 serves commuter and visitor traffic traveling between population centers of Lake Havasu City,AZ and Bullhead City,AZ/Laughlin,NV on the Colorado River and its desert *** intersection features 180 total vehicle-to-vehicle conflict points inclusive of 126 crossing *** paper presents the County’s technical and administrative approach and techniques in planning and developing the CR 1“Six Points”roundabout given the(1)absence of fatal and incapacitating injury crash history and(2)backdrop of this improvement representing the County’s first *** initiation entailed the County securing a Federal share of Highway Safety Improvement Program funding at *** design commenced with a preliminary engineering study to identify,evaluate,and solicit public input on alternative improvement solutions as part of validating the roundabout improvement as superior for traffic operations,community and business function,sitting,and *** input targeted preference for maintaining CR 1 uninterrupted flow versus interrupted flow introduced under roundabout *** simple decision tree enabled the County to understand existing operational and access conditions important to the public,business owners,and public safety providers for purpose of configuring a roundabout improvement satisfying local motorist and community needs,which stoked stakeholder buy-in on the project.

关键词： roundabout thru-about safety skewed intersections predictive modeling benefit-cost

A review of traffic behaviour and intelligent driving at roundabouts based on a microscopic perspective

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Transportation Safety and Environment 2024年第3期6卷 1-16页

作者： Haobin Jiang Qingyuan Shen Aoxue Li Chenhui Yin Automotive Engineering Research Institute Jiangsu UniversityZhenjiang 212013JiangsuChina School of Automotive and Traffic Engineering Jiangsu UniversityZhenjiang 212013JiangsuChina

The contradiction between increasing traffic and the relatively poor roundabout infrastructure is getting *** control and optimization of the macroscopic traffic flow needs to be improved to resolve congestion and safety problems at roundabouts and the connected road *** order to better understand the gaps and trends in this field,we have systematically reviewed the main research and developments in traffic phenomena,driving behaviour,autonomous vehicles(AVs),intelligent connected vehicles and real vehicle trajectory data sets at *** study is based on 388 papers about roundabouts,selected through a comprehensive literature *** review demonstrates that based on a microscopic perspective,sensing,prediction,decision-making,planning and control aspects of AVs and intelligent connected vehicles can be designed and optimized to fundamentally and significantly improve traffic capacity and driving safety at ***,the generation mechanism of traffic conflicts among traffic participants at roundabouts is complex,which is a tremendous challenge for the systematic design of ***,based on naturalistic driving data and machine learning theory,it is an important research direction to build driver models by learning and imitating human driver decision-making and driving behaviours.

关键词： autonomous vehicles driving behaviour naturalistic driving data roundabout traffic capacity