Traffic Organization Optimization of Urban Road Combined Intersections

With the development of the economy and the acceleration of urbanization, the number of vehicles in cities is increasing rapidly, which greatly increases the pressure on urban traffic. Solving traffic accidents and problems to keep smooth travel and safe travel has become a top priority in road construction. In this paper, how to optimize the traffic at the intersection of the urban road was discussed with the aim of reducing traffic accidents and problems to keep peoples’ smooth travel and safe travel.

Transit Bus and Pedestrian Safety Analysis in the Context of Operator Improvements and Traffic Volume Assessment

Pedestrian safety related to public bus transit is an integral part of promoting sustainability especially in the urban setting. This concept has received significant attention within the last decade as transit agencies strive to make their systems more sustainable and safer at the same time. This study examined pedestrian collisions related to public transit buses in Philadelphia over a three-year study period from 2008 to 2011. The objective is to perform a detailed analysis on crash records, which provides the foundation on statistics for bus-pedestrian collision to allow for future studies in modeling work in this field. Results of this research provided insights on bus-pedestrian collisions in terms of bus maneuver, cause of crash, impact point of bus, and relation to hourly traffic volume. A strong correlation was found between traffic volume and bus-pedestrian collision rate in terms of hours of the day. For any given hour, an increase in collision frequency was found if the traffic volume exceeds a threshold of 5% of its average annual daily traffic. This serves as an indicator of locations that pedestrians are vulnerable at. Analyses were conducted to the fullest extent allowable by the limited dataset. This study presents findings that can be future developed and investigated in future studies. Additionally, countermeasures are recommended in each section that presents a critical area to address.

Green-Wave Traffic Theory Optimization and Analysis

This paper analyzed the applicable conditions of the Green-Wave traffic theory, used two-phase signal control concept to optimize the Green-Wave traffic theory, put forward specific program for cross intersections and T-intersections. The analysis concluded that the optimized Green-Wave traffic theory is favorable to improve road safety and reduce vehicle fuel consumption and reduce vehicle emissions and other aspects.

Traffic Conflict Technique Development for Traffic Safety Evaluation under Mixed Traffic Conditions of Developing Countries

In developing countries, the numbers of traffic accidents, injuries and fatalities are very high and tend to increase atsignalized intersections. For example, in Ho Chi Minh City （HCMC） of Vietnam, the number of accidents at signalized intersectionsaccounted for 45% of the total accidents at all the intersections. This fact leads to strong necessity for analyzing traffic safety atsignalized intersections. Nevertheless, the historical accident data in HCMC is not available for deep analysis, this study uses videocameras to capture and analyze conflicts that potentially lead to accidents using TCT （traffic conflict technique）. Conflict severityidentification is one of the most significant steps to evaluate traffic safety at signalized intersections using TCT. Six zones （seriousconflict, common conflict, non-conflict, highest potential serious conflict, potential serious conflict, and potential common conflict） areexplored in this study to clarify conflict severity. This result is based on being the cut off value between serious conflicts and commonconflicts, according to 85% cumulative frequency of TTC （time to collision） and CS （conflict speed） under 3,050 samples size whichwere observed at 10 signalized intersections during August-November, 2014. Such a deep understanding is a scientific basis to studyhow to apply TCT to evaluate traffic safety at signalized intersections under mixed traffic conditions.

Characteristics and risk of violation behavior of non-motorists at signalized intersections

Aiming at prevalent violations of non-motorists at urban intersections in China, this paper intends to clarify the characteristics and risks of non-motorist violations at signalized intersections through questionnaires and video recordings, which may serve as a basis for non-motorized vehicle management. It can help improve the traffic order and enhance the degree of safety at signalized intersections. To obtain the perception information, a questionaire survey on the Internet was conducted and 972 valid questionnaires were returned. It is found that academic degree contributes little to non-motorist violations, while electrical bicyclists have a relatively higher frequency of violations compared with bicyclists. The video data of 18 228 non-motorist behaviors indicate that the violation rate of all non-motorists is 26.5%; the number of conflicts reaches 1 938, among which violation conflicts account for 66.8%. The study shows that the violation rates and the violation behavior at three types of surveyed intersections are markedly different. It is also concluded that the conflict rates and the violation rates are positively correlated. Furthermore, signal violation, traveling in the wrong direction, and overspeeding to cross the intersection are the most dangerous among traffic violation behaviors.

A Workable Solution for Reducing the Large Number of Vehicle and Pedestrian Accidents Occurring on a Yellow Light

Traffic intersections are incredibly dangerous for drivers and pedestrians. Statistics from both Canada and the U.S. show a high number of fatalities and serious injuries related to crashes at intersections. In Canada, during 2019, the National Collision Database shows that 28% of traffic fatalities and 42% of serious injuries occurred at intersections. Likewise, the U.S. National Highway Traffic Administration (NHTSA) found that about 40% of the estimated 5,811,000 accidents in the U.S. during the year studied were intersection-related crashes. In fact, a major survey by the car insurance industry found that nearly 85% of drivers could not identify the correct action to take when approaching a yellow traffic light at an intersection. One major reason for these accidents is the “yellow light dilemma,” the ambiguous situation where a driver should stop or proceed forward when unexpectedly faced with a yellow light. This situation is even further exacerbated by the tendency of aggressive drivers to inappropriately speed up on the yellow just to get through the traffic light. A survey of Canadian drivers conducted by the Traffic Injury Research Foundation found that 9% of drivers admitted to speeding up to get through a traffic light. Another reason for these accidents is the increased danger of making a left-hand turn on yellow. According to the National Highway Traffic Safety Association (NHTSA), left turns occur in approximately 22.2% of collisions—as opposed to just 1.2% for right turns. Moreover, a study by CNN found left turns are three times as likely to kill pedestrians than right turns. The reason left turns are so much more likely to cause an accident is because they take a driver against traffic and in the path of oncoming cars. Additionally, most of these left turns occur at the driver’s discretion—as opposed to the distressingly brief left-hand arrow at busy intersections. Drive Safe Now proposes a workable solution for reducing the number of accidents occurring during a yellow light at intersections. We believe this fairly simple solution will save lives, prevent injuries, reduce damage to public and private property, and decrease insurance costs.

Safety Analysis for Older Drivers at SignalizedIntersections

The proportions of older drivers continue to increase since baby boom generation is becoming old. The level of mobility of older drivers is also increasing. Older drivers begin to noticeably be over-involved in fatal crashes. Intersections appear to be hazardous to older drivers, particularly left turn due to one or more of. sensory, perceptual, cognitive, physical and general driving knowledge deficiencies. The safety concern of older drivers is also becoming significant. Ten years of crash data has been extracted from Kansas accident report system. It has been analyzed using SAS （statistical analysis system） software. Five different age groups have been considered. Comparison has been made between different age groups of the same gender, and the same age group for different gender. Effects of light condition, weather condition, surface type, surface condition, road character and construction/maintenance zone on older drivers＇ safety have also been considered in this study. It has been found out that proportion of older drivers in through movement involved in accident decreases as age increases whereas the proportion of left turn accidents increases with age, left turn is harder for females in all age groups, and proportion of right turn accidents has no specific trend. Most of the accidents have taken place during daylight when there are no adverse weather conditions on dry surface, straight and level road, and blacktop surface type.

Recognition of occluded pedestrians from the driver's perspective for extending sight distance and ensuring driving safety at signal-free intersections

Urban intersections without traffic signals are prone to accidents involving motor vehicles and pedestrians.Utilizing computer vision technology to detect pedestrians crossing the street can effectively mitigate the occurrence of such accidents.Faced with the complex issue of pedestrian occlusion at signal-free intersections,this paper proposes a target detection model called Head feature And ENMS fusion Residual connection For CNN(HAERC).Specifically,the model includes a head feature module that detects occluded pedestrians by integrating their head features with the overall target.Additionally,to address the misselection caused by overlapping candidate boxes in two-stage target detection models,an Extended Non-Maximum Suppression classifier(ENMS)with expanded IoU thresholds is proposed.Finally,leveraging the CityPersons dataset and categorizing it into four classes based on occlusion levels(heavy,reasonable,partial,bare),the HAERC model is experimented on these classes and compared with baseline models.Experimental results demonstrate that HAERC achieves superior False Positives Per Image(FPPI)values of 46.64%,9.59%,9.43%,and 6.78%respectively for the four classes,outperforming all baseline models.The study concludes that the HAERC model effectively identifies occluded pedestrians in the complex environment of urban intersections without traffic signals,thereby enhancing safety for long-range driving at such intersections.

Analysis of opposing left-turn conflicts based on traffic conflict technology

The relationship between the opposing left-turn conflict and the traffic participants was analyzed in this study. Based on the traffic conflict technology, the image data were collected in a real traffic situation. The relationship was investigated under two different conditions. The number of opposing left-turn conflicts was positively correlated with the number of left-turn vehicles while the ratio of left-turn vehicles to opposing vehicles was less than 1, and showed a positive correlation with the number of opposing-through vehicles when the ratio of left-turn vehicles to opposing vehi- cles was more than 1. In other words, the opposing left-turn risk was positively correlated with the number of the minor traffic participants, which had a negative effect on the whole traffic system op- eration.

Analysis of bicyclist-vehicle crash at intersection area considering behavior prior to crash:A random parameter ordinal probit approach

In order to analyze the risky factors that affect vehicle-cyclist crash injury severity at the intersection area,especially the factors relating to the road users behaviors,an empirical study was conducted by collecting accident records from 2011 to 2015 from the General Estimates System.After preliminary screening,the variables were classified into 5 main categories including cyclists characteristic and behavior,drivers characteristic and behavior,vehicle characteristic,intersection condition,and time.The random parameter ordinal probit(RPOP)was used to study the significant influencing factors and corresponding heterogeneity.The results show that failing to obey traffic signals,failing to yield to right-of-way,dash and drinking before cycling can increase the injury severity for cyclists,and the corresponding fatal injury likelihoods increase by 53.2%,40.0%,86.3%,and 211.5%,respectively.Moreover,drivers inattention,speeding,going straight and left turning increase the risk of crashing for cyclists.The corresponding fatal injury likelihoods increase by 134.5%,186.5%,69.3%,and 22.7%,respectively.Other indicators such as age,gender,vehicle type,traffic signal and intersection type can also affect injury severity.

Investigation of the Skid Resistance at Accident Occurred at Urban Intersections

Skid resistance of road surface plays an important role on urban traffic accidents. It is thought that reduction of surface microtexture leads to reduced skid resistance. Hence, it affects driving safety negatively and may cause traffic accidents, This paper is about the effect of skid resistance and intersection safety. Urban four leg signalized intersections were selected from Isparta city. The surface frictional properties were measured and it was tried to find critical skid resistance value with the help of British Pendulum Tester. Macro texture values of the intersections were determined with Sand Patch test and concluded that surface macro texture contributes to skid resistance. An analysis technique based on probabili theory has been used. This method is used for expounding the interaction between skid resistance-intersection and accident rates. After the study results are evaluated, it is understood that pavement roughness is very important for urban intersection safety measures.

信号交叉口电动自行车多类别违规行为分析与建模

电动自行车违规行为对信号交叉口通行效率和安全具有显著的影响,是重要的安全管控对象。文中基于视频录像调查法获得的信号交叉口9726辆非机动车数据,对比分析了3类非机动车在骑行者个人属性和时空场景影响下的违规行为特征。以骑行者个人属性、信号交叉口特征和交通流特性3方面共14个因素作为协变量,构建基于多元Logistic回归的电动自行车多类别违规行为模型,以揭示信号交叉口电动自行车闯红灯骑行、占用机动车道骑行、越线等待和逆向骑行行为机理。研究结果表明:电动自行车在信号交叉口总体违规率为44.01%,是传统自行车的1.21倍;中老年电动自行车骑行者发生4种违规行为的可能性高于青年;女性骑行者更易发生越线等待和逆向骑行违规行为,男性骑行者更易发生占用机动车道骑行;增设协管员可有效降低电动自行车在信号交叉口的闯红灯、越线等待和逆向骑行行为,但同时会增加电动自行车占用机动车道骑行的可能性;设置左转专用相位能有效降低电动自行车占用机动车道骑行、越线等待和逆向骑行行为。

基于双层规划模型的“才”字形交叉口禁流向交通组织方法研究

为解决城市多路交叉口车流复杂导致的交通拥堵和交通安全问题,针对多路交叉口中的“才”字形交叉口,明确其特点,对交叉口部分交通流向禁行的必要性进行分析。基于双层规划构建交叉口禁流向交通组织模型,以局部路网中车均行驶时间最小为目标,判别交叉口各流向车流是否禁行,并确定禁流向后交通组织方案,减少交叉口内车流及冲突点数量。以哈尔滨市学府路—西大直街交叉口为例,比较禁流向交通组织方案和单向交通组织方案,发现此交叉口禁流向交通组织更优,冲突点个数减少52%,路网车均行驶时间下降0.98%。考虑交通量变化分析禁流向交通组织模型的适用性,发现OD量变化超过26%时模型适用性较差,潮汐现象明显的交叉口,应设置单向交通组织。

Assessment of traffic performance measures and safety based on driver age and experience:A microsimulation based analysis for an unsignalized T-intersection

Traffic safety and performance measures such as crash risk and queue lengths or travel times are influenced by several important factors including those related to environment,human,and roadway design,especially at intersections.Previous research has studied different aspects related to these factors,yet these characteristics are not fully investigated with a focus on age and experience of drivers.In this paper,we investigate this issue by using a two-phase approach via a case study application on a critical T-intersection in the City of Tallahassee,Florida.The first phase includes a scenario-based microsimulation analysis through the use of a microscopic simulation software,namely VISSIM,to illustrate the variations in traffic performance measures with respect to driver compositions of different age groups in the traffic stream.A variety of scenarios is created where the driving characteristics are provided as inputs to these scenarios in terms of decision making and risk taking.This is also supported by a sensitivity analysis conducted based on the driver composition in the traffic.The second phase includes the analysis of microsimulation outputs via a tool developed by Federal Highway Administration tool,namely the Surrogate Safety Assessment Model(SSAM),in order to determine the traffic conflicts that occur in each scenario.These conflicts are also compared with real-life crash data for validation purposes.Results show that(a) the differences in risk perception that affect driving behavior might be significant in influencing traffic safety and performance measures,and(b) the proposed approach is considerably successful in simulating the actual crash conflict points.

考虑均值及方差异质性的外卖骑手闯红灯行为影响因素分析

针对外卖骑手闯红灯事件频发、事故风险隐患较高的问题,调查了西安市多个信号交叉口处外卖骑手的闯红灯行为。将闯红灯行为作为因变量,将骑手个人特征、穿越行为特征、交通及环境特征等作为自变量,构建了考虑均值及方差异质性的随机参数Logit模型。采用Halton序列抽样进行参数估计,并结合参数估计结果和平均边际效应值量化分析各自变量对因变量的影响。结果表明:“饿了么”和“UU跑腿”的骑手闯红灯概率较低,到达时段为红灯第2段或第3段、停车线之后等待通行、冲突方向机动车流量较大等变量也会显著降低闯红灯概率,而同向违章人数增加、午高峰、晚高峰等变量会显著增加闯红灯概率。其中,使闯红灯概率提升最大的变量为晚高峰,其平均边际效应为0.278;使闯红灯概率降低最大的变量为停车线后等待,其平均边际效应为-0.222。此外,停车线后等待和晚高峰为随机参数变量,参数均服从正态分布,其均值和标准差分别为-1.379,1.359和2.502,5.360,且都具有显著的均值及方差异质性。对于停车线后等待这个变量,红灯第2段会同时提高其参数均值和方差,即增加闯红灯的概率,并增加该变量对闯红灯行为影响的随机性。对于晚高峰变量,机动车流量较大会同时降低其参数均值和方差,即降低闯红灯的概率,并降低该变量对闯红灯行为影响的随机性。此外,违章人数为1也会降低晚高峰参数的方差。

城市快速路施工交通组织与交通安全分析

快速路建设不可避免地要占用现状道路,占道施工导致道路通行能力降低,周围路网压力增大,交通安全隐患增加。为确保道路的安全与畅通,必须制订施工期间交通组织方案。以烟台市港城西大街互通立交节点快速路为例,分析快速路占道施工交通特性,指出施工期间存在的主要问题,提出施工期间交通组织优化方法和安全保障措施。

城市核心区道路交叉口交通组织优化与评估

城市核心区道路交叉口畅通是城市路网系统高效运营的关键。本文选取新一线城市佛山顺德区核心区域的兴顺路与京珠线交叉口为研究对象。在对区域交通现状实地调查调查的基础上,采用饱和度评价、平均延误评价、最佳信号周期评价等研究方法,对兴顺路与京珠线交叉口的交通组织进行优化设计,从交叉口的渠化、信号配时等方面,提出了交叉口北进口处设置待转区和交叉口北进口处设置借道左转的2种方案,通过对方案进行评估和比较,最终确定交叉口北进口处设置借道左转的方案更优,以此为佛山市核心道路交叉口的交通优化提供参考和借鉴。

交通救援应急中转路径调度数学模型构建仿真

由于交通状况往往是动态变化的,包括交通拥堵、道路封闭等情况,救援应急时导致车辆中转路径调度救援应急难度加大。为进一步提升应急救援时救援车的救援效果,提出交通救援应急中转路径实时调度数学建模方法。根据城市交通中信号交叉口车辆的微观运行特征,确定车辆应急救援时道路交叉路口应急安全状态;设计救援应急中转路径调度模型,将模型分为上下两个层级,结合混合布谷鸟算法求解模型,完成救援应急中转路径实时调度。实验结果表明,利用上述方法开展救援应急中转路径实时调度时,路径中转次数最多仅为10次,耗时为150ms,调度效果好、性能高。

基于车流波动理论的匝道达到控制与仿真效果评价

以匝道达到控制为主体的合流区主动交通管控是高速公路与城市快速路在提升交织区通行能力与交通安全采用的重要方法。采用历史真实交通数据,结合优化的速度波动理论模型,构建车辆在拥挤流交织过程中的运行状态模型,量化分析混合控制决策下最优化的管控方案,并通过优化的仿真平台,获取车辆轨迹、分布及冲突状况等信息,验证结论的实际效果。以秦洪立交为例进行模型试验论证,对比匝道单一控制与匝道主线混合控制的优化效果。结果表明,相对于无管控状态,单一匝道控制下冲突减少52.5%,但车辆延误增长20.5%;混合控制下冲突减少68.1%,且车辆延误降低12.0%。由此可知控制模型对匝道交通安全与效率有明显优化效果。其中,采用匝道主线混合控制时效果最佳,有效提升匝道通行效率和交通安全效益。

城市道路交叉口提升改造技术研究

随着国家城镇化进程的不断推进,现状城市道路交叉口的服务能力已不能满足日益增长的交通需求。以某四线城市两条主干路平面交叉口为例,分析交叉口现状、交通量,同时综合考虑红线范围、城市景观、交通干扰、投资等方面影响因素,提出改造思路,为既有道路交叉口从近期与远期两方面的提升改造提出合理的分析与建议,为既有城市道路交叉口的提升改造提供参考。