基于ISO 26262的车道偏离预警系统概念设计与仿真

以道路车辆功能安全规范标准ISO 26262为准则,对汽车的车道偏离预警系统（LDWS）进行了概念设计。首先分析了ISO 26262功能安全规范概念阶段的活动内容,并在此基础上,完成车道偏离预警系统的项目定义、危险分析和评估,设计了功能安全概念的相关工作,确定了功能安全等级和安全目标。最后搭建了UML仿真模型对LDWS概念设计阶段进行仿真测试,测试结果表明此设计能够满足ISO 26262规范标准,实现了车道偏离预警系统的功能安全概念设计,对车道偏离预警系统的安全开发具有指导意义。     

山区高速公路紧急避险车道安全性评价研究

为评价避险车道安全性,笔者从系统工程角度出发,对渐变段及引道参数、制动床参数、安全设施、附属设施4个方面构建了避险车道安全评价指标体系。采用AHP和改进TOPSIS相结合的方法,建立了避险车道安全性评价模型,提出了避险车道安全性分级标准,并以贵州仁赤高速K63+340、K86+200、K94+150 3处避险车道为例,对其进行了安全性评价,结果表明,K63+340避险车道安全水平为Ⅱ级,安全性好;K86+200避险车道安全水平为Ⅴ级,K94+150避险车道安全水平为Ⅲ级,安全性差。最后,针对避险车道存在的问题,提出了改善建议,旨在为避险车道设计及改造提供参考,从而提高避险车道安全性。     

基于驾驶模拟的高速公路施工围挡位置熵权模糊综合评价

施工围挡是道路施工区常用的交通安全设施,合理设置施工区围挡位置对保障施工区交通安全和节约施工区用地资源具有重要作用.以典型改扩建的高速公路为研究对象,利用驾驶模拟技术,在硬路肩有限的工作面内,设计3种外侧车道与施工围挡间距的模拟场景(0.5 m、0.75 m、1.0 m),组织开展40人的驾驶模拟对比试验,采集驾驶行为、眼动特性和生理信号等数据,采用配对t检验分析试验数据的可靠性,并提出由7项指标组成的评价指标体系,构建了基于熵权法的模糊综合评价模型,提出高速公路施工围挡位置熵权模糊综合评价方法,对3种高速公路施工围挡场景进行了比较分析和安全评价.结果表明:驾驶模拟器和试验场景均不会对试验造成不利影响;外侧车道与施工围挡间距为0.5 m的方案计算分值最高,综合响应表现最好.高速公路路侧施工围挡与外侧车道为0.5 m的距离,有效兼顾了节约用地范围和保障行车安全,可为科学设置高速公路施工围挡提供决策参考.     

以拓宽扩建契机完善高速公路交通安全构建的思考

为适应经济的快速发展,给福建海西建设创造更加安全、顺畅、便捷的道路通行条件,福厦漳高速公路拟将由原有的双向四车道扩建增容为双向八车道。扩建后其车流量、流速将大大增加,对道路交通设施、管理手段都将提出更高的要求。亟待我们分析总结双向四车道的交通管理需求,借鉴外省已有八车道高速公路交通安全设施建设的经验,以科学发展观来科学研判,大胆预测,对扩建中交通安全设施设置的科学性、合理性、前瞻性地提出看法和建议,以期为日后的交通安全管理工作奠定良好的硬件基础。     

一种新型高速公路入口设计及其污染物减排效果分析

针对传统双车道匝道入口设计存在的主要问题,提出一种新型双车道匝道入口设计方案,并运用Paramics Discovery 21.0软件进行交通仿真和AIRE软件进行机动车污染物排放量统计计算。结果表明,该方案通过内、外侧匝道合流点分离式设计,将匝道车辆与主线车辆的合流点分散,减小了匝道车辆对主线车辆的干扰。同时,该设计方案与传统方案相比,对于6车道高速公路,匝道交通量1 000 veh/h情况下,机动车车均NOx、PM10及碳污染物排放量分别降低约12.1%、7.0%、10.9%;匝道交通量1 250 veh/h情况下,3种污染物车均排放量分别平均降低约13.3%、6.2%、11.0%。同时,随主线和匝道交通量增大,新型分离式入口较传统直接式入口车辆的车均排放量降低量更大,即新型分离式入口设计更适用于主线交通量和匝道交通量均较大时的情况。另外,4车道和8车道2种高速公路中,匝道交通量1 000veh/h情况下,4车道和8车道高速公路新型入口车均NOx排放量分别较传统入口平均降低约18.3%、10.5%,PM10排放量分别降低约9.0%、6.3%,碳污染物排放量分别降低约13.5%、10.2%,即新型分离式入口设计对4车道高速公路的减排效果更为明显。     

关注内侧式公交专用车道

在福州,一条将改变市民乘坐公交车习惯的内侧式公交专用道,今年底将投入试营运。公交专用道,是指在特定路段上,通过标志、标线等划出一条或几条车道给公交车专用,同时,公交车仍享有在其他车道行驶的权利。其设计方式分为中央(内侧式)公交专用道、逆向公交专用道、城市高架下的公交专用道。内侧式公交专用道即在道路内侧设置公交专用通道,它位于道路中     

"美媚"开车

一天,放松地行驶在市区干道上,临近红绿灯的时候,突然有一辆行驶在左转车道上的POLO插到我前面,不由地紧急刹车。透过车窗,看到一位美媚两手紧握方向盘,目光坚定地看着前方,好像无视我车的存在。我会心一笑,不禁想起这些年来所看到的美媚行车,总结起来,大体如此:在路上,如发现前面有辆车     

“车困榕城”:把脉与开方

把脉 部分红绿灯设置不科学 现在许多路口采用红色车道灯,使右转弯车辆停车候行,这是道路堵塞的重要原因之一。各种车辆,特别是出租车、公交车任意改换行车道,也是造成堵车的重要原因之一。因此,增加黄灯闪亮时间,改右转弯红色车道灯为红色灯,禁止各种车辆任意改变行车道左右穿梭,对大车占用快车道慢速行驶进行处罚等,也许     

未按规定导向车道行驶行为干预方法研究

为保障信号交叉口的正常交通秩序,充分遏制机动车未按规定导向车道行驶行为,亟需探究该行为的影响因素及干预方法。以北京市内4个信号交叉口处共35 h的1 666条监控视频数据为基础,对未按规定导向车道行驶行为进行定义并将其分为9类,分别对频率较高的5类未按规定导向车道行驶行为构建二元Logit模型,以确定其关键影响因素,并据此提出干预方法。结果表明,排队车辆数、大车比例、时段、车流量、照明条件等因素会不同程度地影响5类未按规定导向车道行驶行为的发生概率,其中排队车辆数及时间因素影响最为显著。在此基础上,从交通工程设施及驾驶人安全意识角度,提出优化交叉口渠化设计及信号配时、采用智能标线、强化监管力度及完善交通管控设施、加强驾驶人安全教育4种未按规定导向车道行驶行为干预方法。     

不确定背景环境下车道检测技术的研究

针对不确定背景的交通环境,提出一种新的车道检测算法。确定道路路面的色彩范围,提取车道标线的色彩信息,消除光照强度变化对车道标线信息提取过程的影响;通过对比车辆与车道标线在大小、形状和运动模式3方面的差异排除车道中车辆对车道线检测的干扰;单帧图像的车道检测结果存储于车道一致性确认模块中,运用车道标志线一致性确认提高车道检测结果的准确性。试验结果表明,该方法能够有效地检测各种天气条件下车道区域以及解决车道遮挡问题。     

Modeling accident occurrence at signalized tee intersections with special emphasis on excess zeros

In implementing effective remedial treatments at hazardous intersections, it often is necessary to identify the geometric and traffic factors that lead to accident occurrence. However, one particular problem frequently encountered in accident studies is how to distinguish virtually safe intersections with little likelihood of accident occurrence from those that have happened to have no accident due to the random process. To deal with this problem, the "excess" records of zero accident, the zero-inflated negative binomial was used to assign the probability to the accident outcome. Accident data at 104 signalized tee intersections in Singapore over a period of 9 years were employed for model development. The model indicates that uncontrolled left-turn slip road, permissive right-turn phase, existence of a horizontal curve, short sight distances, large number of signal phases, total approach volume, and left-turn volume may increase accident occurrence. On the other hand, right-turn channelization, acceleration section on the left-turn lane, median railings, and more than 5% approach gradient may reduce accident occurrence. Moreover, there is a trend of reducing accidents over the years.     

Evaluation of left-turn lane offset using the naturalistic driving study data

IntroductionThe Strategic Highway Research Program 2 (SHRP 2) Naturalistic Driving Study (NDS) data were used to evaluate gap acceptance behavior of drivers at left-turn lanes with negative, zero, or positive offsets ranging from − 29 ft to + 6 ft. The objectives of the study were to develop guidance for the design of offset left-turn lanes used as a safety countermeasure, and to provide insight regarding the use of the NDS data to future users.MethodThe study included 3350 gaps in opposing traffic evaluated by 145 NDS volunteer drivers and 275 non-NDS drivers at 14 two-way stop-controlled intersections and 44 signalized opposing left-turn pairs. Logistic regression was used to model the critical gap length for drivers as a function of offset, under conditions when their view was either blocked or not by an opposing left-turning driver.ResultsThe analysis found that the critical gap was longer at left-turn lanes with negative offsets than at those with zero or positive offsets, and was also longer when sight distance was blocked by an opposing left-turning vehicle. Sight distance was much more likely to be restricted by an opposing left-turning vehicle at negative-offset and drivers at those intersections were less likely to accept a gap when an opposing left-turn driver was present.ConclusionsLonger gap lengths could potentially result in decreased operational efficiency of an intersection. In addition, drivers making left-turns at negative-offset left-turn lanes are, on average, more likely to leave the shortest amount of time between their turn and the arrival of the next opposing through-vehicle, which may present a potential safety concern.Practical applicationsThe findings provide guidance for highway designers considering using offset left-turn lanes as a crash countermeasure. This research also highlights the benefits and limitations of using the SHRP 2 NDS data to answer similar research questions.     

The effects of left-turn traffic-calming treatments on conflicts and speeds in Washington,DC

Introduction: Left-turning vehicles pose considerable safety risks to pedestrians at intersections. Left-turn traffic-calming treatments are designed to slow left-turn traffic. This study examined the effects of one type of left-turn calming, the hardened-centerline treatment, on the numbers of conflicts between left-turning vehicles and pedestrians and left-turn speeds in Washington, DC. Method: Numbers of conflicts between left-turning vehicles and pedestrians, as well as left-turn speeds, were collected at selected intersections in Washington, DC, where the hardened centerline was installed, as well as at control intersections in the city where no treatment was installed, before and after installation. Poisson regression evaluated the change in numbers of conflicts associated with the hardened-centerline treatment. The effect of the treatment on left-turn speeds was estimated by a log-linear regression model, and the effect on the odds of left-turning vehicles exceeding 15 mph was estimated by a logistic regression model. Results: The treatment was associated with a 70.5% reduction in conflicts between left-turning vehicles and pedestrians, a 9.8% reduction in mean left-turn speeds, and a 67.1% reduction in the odds of left-turning vehicles exceeding 15 mph. All the reductions were statistically significant. Conclusions: The study demonstrates that the hardened-centerline treatment can reduce conflicts between left-turning vehicles and pedestrians, and slow down left-turn traffic at intersections. Practical applications: The treatment should be added to the toolbox for communities looking to improve pedestrian safety at intersections.     

Motorcyclist perception response time in stopping sight distance situations

One of the most effective engineering measures is the provision of an exclusive motorcycle lane that separates motorcycles from other mixed traffic to reduce traffic congestion and motorcycle crashes. Even though the existing exclusive motorcycle lanes in Malaysia reduced the incidents of motorcycle crashes with other vehicles, the design of this special motorcycle lane was based on a cross reference between a bicycle track and a highway. Thus, a suitable design guide is yet to be developed for the geometrical design of a proper and safer exclusive motorcycle lane. Safe stopping sight distance (SSD) has been recognized as a criterion for road design and should be taken into account. Motorcyclist perception response time (PRT) is the time from detection object until the rider reduces motorcycle speed in braking action is an essential component of motorcycle SSD. Two road experiments were conducted to obtain empirical values of motorcycle PRT to expected and unexpected objects. In the expected condition, 89 motorcyclists applied brake as quickly as possible following activation of a light beside the road. In the unexpected condition, 16 riders responded by braking in response to an obstacle that appeared suddenly in their lane. The mean PRT to expected and unexpected object is 0.71 s and 1.25 s respectively. The 85th percentile PRT to unexpected object is 2.12 s. This study found that most riders are capable of responding to an unexpected object along the roadway in 2.5 s or less. Therefore, PRT of 2.5 s is an appropriate value for motorcycle lane geometric design.     

Two-way left turn lane or raised median? A truck safety based study

Introduction: Due to their size and weight, trucks require more space and time to make left turns when exiting or entering a roadway. Therefore, appropriate median treatments are critical for roadways with substantial truck traffic. The two-way left-turn lane (TWLTL) and raised median (RM) are the two types of median most commonly used to improve roadway mobility and manage roadway accessibility. However, previous studies on these median treatments have focused primarily on the general traffic conditions and geometric roadway features without considering the truck traffic impact. Method: To fill this gap, this study investigates the truck impacts on TWLTL and RM by considering two major influencing factors – truck percentage and roadway access point density. First, a negative binomial regression is developed to analyze the relationship between crash frequency and various influencing factors. Next, the crash rate difference analysis between the TWLTL and RM is conducted to identify critical points for these two factors. Results: The findings indicate that, compared with RM, TWLTL has significantly higher crash frequency, especially for roadways with a higher percentage of trucks. This suggests that the percentage of trucks should be taken into consideration when selecting an appropriate type of roadway median.     

Effect of novel divergence markings on conflict prevention regarding motorcycle-involved right turn accidents of mixed traffic flow

Introduction: In Taiwan, segregated traffic flow countermeasures have long been in place. Although these facilities have decreased the numbers of motorcycle left-turn collisions, right-angle collisions, and sideswipe collisions, they have also induced serious right-turn accidents. The purpose of this research was to evaluate an intervention intended to decrease conflicts and motorcycle-involved crashes. In this study, the reasons why the motorcycle accident rate is higher at intersections with slow lanes than at those without slow lanes are presented, and the theory of the self-explaining road was applied to create divergence markings for a mixed traffic flow environment. An intervention that guides motorcycles and cars into appropriate locations at intersections was applied to three intersection approaches. Method: The intervention effectiveness was evaluated by comparing the number of accidents at the intersections before and after the implementation of improvement measures. Moreover, video recordings were used to analyze the traffic distributions at the cross-sections of intersections. T-test was adopted to examine whether the traffic flows at the cross-sections of the intersections before and after the intervention were statistically different. In addition, this research applied the post-encroachment time (PET), the time between the first road user leaving the encroachment zone and the second road user arriving in it, to evaluate traffic conflicts. Finally, the PET and severity index between a straight-through motorcycle and a right-turn vehicle were analyzed. Results: PET increased by 3.2%–20.4%, and the rates of right-turn collisions, sideswipe collisions, and rear-end collisions decreased by 64.3%, 77.3%, and 61.5% respectively. Conclusions: Eliminating the slow traffic lane and setting divergence markings may not effectively cause vehicles in different driving directions to drive in the proper locations in the lanes. However, divergence markings both reduce the rate of right-turn collisions and decrease the incidence of sideswipe and rear-end collisions. Practical applications: The proposed design method may be a good design reference for countries having a high motorcycle density.     

Driver Behavior During Overtaking Maneuvers from the 100-Car Naturalistic Driving Study

Objective: Lane changes with the intention to overtake the vehicle in front are especially challenging scenarios for forward collision warning (FCW) designs. These overtaking maneuvers can occur at high relative vehicle speeds and often involve no brake and/or turn signal application. Therefore, overtaking presents the potential of erroneously triggering the FCW. A better understanding of driver behavior during lane change events can improve designs of this human–machine interface and increase driver acceptance of FCW. The objective of this study was to aid FCW design by characterizing driver behavior during lane change events using naturalistic driving study data.

Methods: The analysis was based on data from the 100-Car Naturalistic Driving Study, collected by the Virginia Tech Transportation Institute. The 100-Car study contains approximately 1.2 million vehicle miles of driving and 43,000 h of data collected from 108 primary drivers. In order to identify overtaking maneuvers from a large sample of driving data, an algorithm to automatically identify overtaking events was developed. The lead vehicle and minimum time to collision (TTC) at the start of lane change events was identified using radar processing techniques developed in a previous study. The lane change identification algorithm was validated against video analysis, which manually identified 1,425 lane change events from approximately 126 full trips.

Results: Forty-five drivers with valid time series data were selected from the 100-Car study. From the sample of drivers, our algorithm identified 326,238 lane change events. A total of 90,639 lane change events were found to involve a closing lead vehicle. Lane change events were evenly distributed between left side and right side lane changes. The characterization of lane change frequency and minimum TTC was divided into 10 mph speed bins for vehicle travel speeds between 10 and 90 mph. For all lane change events with a closing lead vehicle, the results showed that drivers change lanes most frequently in the 40–50 mph speed range. Minimum TTC was found to increase with travel speed. The variability in minimum TTC between drivers also increased with travel speed.

Conclusions: This study developed and validated an algorithm to detect lane change events in the 100-Car Naturalistic Driving Study and characterized lane change events in the database. The characterization of driver behavior in lane change events showed that driver lane change frequency and minimum TTC vary with travel speed. The characterization of overtaking maneuvers from this study will aid in improving the overall effectiveness of FCW systems by providing active safety system designers with further understanding of driver action in overtaking maneuvers, thereby increasing system warning accuracy, reducing erroneous warnings, and improving driver acceptance.     

Investigating lane change behaviors and difficulties for senior drivers using naturalistic driving data

Introduction: Lane changes can be a complicated maneuver occurring a dynamic environment requiring the integration of many streams of information. Older drivers may struggle with lane changes which may elevate crash risk. Methods: Real-world lane change behaviors were examined using the Second Strategic Highway Research Program Naturalistic Driving Study database. A total of 393 lane changes were observed for two age groups: middle-aged (30–49), and older (70+) drivers. Results: Older drivers were highly likely to fail to execute an over-the-shoulder glance prior to initiation of a lane change (in 98% of left lane changes and 92% for right lane changes). Older drivers also showed higher rates of OTS glance errors at any point during the lane change in 95% of left lane changes and 86% of right-lane changes. Additionally, older drivers frequently failed to activate the turn signal prior to lane change initiation (60% of lane changes for right changes and 59% for left lane changes). Of the older drivers that made side mirror glances, many occurred after the initiation of the maneuver (46% of left lane changes and 58% of right lane changes) suggesting glances were occurring while changing lanes. Conclusions: Results for older drivers showed that many key glances (particularly side mirror checks) and turn signal actuations observed in the current study occurred after the initiation of the lane change, ostensibly when this action may be too late to gather relevant information and avoid a conflict. Practical Applications: Knowledge of glance patterns during lane changes for older drivers can help older drivers maintain travel mobility as they age. Either through training to reinforce OTS and side mirror glances, or supplemental devices like convex mirrors or oversized rearview mirrors, older drivers can reduce high-risk lane change maneuvers and help older drivers to maintain their mobility and independence longer.     

基于可接受安全间距的单车道交通流模拟模型

交通流微观模拟是采用计算机对交通流进行描述及分析的方法。尤其对于复杂的交通流而言,微观模拟具有明显的优势,然而模拟的准确与否,关键在于模型的建立。笔者即是在研究我国单车道交通流特点的基础上,借鉴车道变换理论,基于驾驶员可接受的交通安全间距,分析安全变换车道的各间距之间的关系,阐述了有超车的单车道交通流模拟模型的建立方法