Application of Connected Truck Data to Evaluate Spatiotemporal Impact of Rest Area Closures on Ramp Parking

Ensuring adequate access to truck parking is critical to the safe and efficient movement of freight traffic. There are strict federal guidelines for commercial truck driver rest periods. Rest areas and private truck stops are the only places for the trucks to stop legally and safely. In locations without sufficient parking areas, trucks often park on interstate ramps, which create safety risks for other interstate motorists. Historically, agencies have employed costly and time intensive manual counting methods, camera surveillance, and driver surveys to assess truck parking. Connected truck data, available in near real-time, offers an efficient alternative to practitioners to assess truck parking patterns and identify areas where there may be insufficient safe parking spaces. This paper presents a case study of interstate I-70 in east central Indiana and documents the observed spatiotemporal impacts of a rest area closure on truck parking on nearby interstate ramps. Results showed that there was a 28% increase in parking on ramps during the rest area closure. Analysis also found that ramps closest to the rest area were most impacted by the closure, seeing a rise in truck parking sessions as high as 2.7 times. Parking duration on the ramps during rest area closure also increased drastically. Although it was expected that this would result in increased parking by trucks on adjacent ramps, this before, during, after scenario provided an ideal scenario to evaluate the robustness of these techniques to assess changing parking characteristics of long-haul commercial trucks. The data analytics and visualization tools presented in this study are scalable nationwide and will aid stakeholders in informed data-driven decision making when allocating resources towards improving the nations commercial vehicle parking infrastructure.

Research on Traffic Safety at Tunnel Entrance and Exit

Highway tunnel entrances have a high rate of expressway traffic accidents.In this paper,the reasons for the high incidence of traffic accidents at highway tunnel entrances are analyzed in detail,and corresponding solutions are proposed,hoping to provide some reference to relevant parties.

Entrance and Exit Defects During Coarse Pitch Orbital Drilling of Carbon Fiber Reinforced Plastic Plates

Formation of entrance and exit defects in coarse pitch orbital drilling(CPOD)of carbon fiber reinforced plastic(CFRP)plates was investigated.Deep observation on entrance and exit morphology shows tear and burr are typical defects.Meanwhile,tear is more obvious than burr,and more entrance tears emerge than exit tears.As one of the major causes of entrance and exit defects in CPOD,cutting forces were substaintially studied by contrast experiments.Then,the effect of cutting parameters on entrance and exit tear was qualitatively analyzed through a single factor test.Experiment results indicate that the variation of rotation speed has little influence on entrance and exit tear.Increasing tangential feed per tooth can enlarge entrance tear,but bring little effect on exit tear.By increasing axial feed pitch,the hole entrance and exit show severe tear.When revolution radius grows bigger and bigger,entrance and exit tear firstly decreases,and then increases.Finally,the models of tear and delamination during CPOD of CFRP were established,the formation mechanisms of entrance and exit defects were revealed,and the control strategies were accordingly put forward.

Analysis and Simulation of Acceptance Gap Control System for Complicated Entrance Ramp on HighClass Roadway

The acceptance gap micro control system applies to the entrance ramp in which the prior consideration is given to the merging safety. Based on the actual condition of interchanges and the vehicle composition in our country, the traffic characteristics for high class roadways are analyzed and the system simulation model is developed. A simulation example is also given in the paper. Through the simulation, the optimal ramp control plan can be obtained.

Detection of keyhole entrance and exit in plasma arc welding

Sensing of keyhole shape and size is important for controlling of plasma arc welding process. In this study, a synchronous vision system is developed by using two CCD cameras to observe the keyhole entrance and exit simultaneously. Experiments are conducted on stainless steel workpiece, Whole keyhole exit image and part of keyhole entrance image are captured synchronously under different welding conditions. Image processing and calibration algorithms are proposed. The boundary and front point of the keyhole entrance and exit are extracted respectively. The effects of welding current and welding speed on ,front point of keyhole entrance and exit are analyzed. Compared to the front point of the keyhole entrance, the position of the front point of the keyhole exit is better to reflect the variation of the welding parameters.

A Study on Location of Facilities of Acceptable Gap Control System of the Entrance Ramp on Expressway

The concept of control system of acceptable gap in the entrance ramp, the construction of the minimum acceptable gap and the method of determining it are introduced. On the above-mentioned basis and by taking the Chinas reality into consideration, the issues on the design of control system of acceptable gap are approached in this paper.

Investigation Motorcycle Safety at Exit Ramp Sections by Analyzing Historical Crash Data and Rider’s Perception

The purpose of this study is to evaluate the safety performance of four exit ramp types and the major contributing factors on motorcycle crashes and injury severity of motorcycle riders. A six-year crash data were collected in Florida, and a web-based survey (234 samples) was conducted. 573 crashes were found at 419 exits, including 178 diamond exits, 71 directional exits, 85 loop exits and 85 outer connection exits. For a diamond exit, both the survey and crash data showed that this type was safer and more preferable by motorcycle riders;while a loop exit was the most dangerous exit due to the sharp curve and a certain length of curve with limited visibility. For a directional exit, longer ramp lengths and the reverse curvature are the major factors causing motorcycle crashes. For an outer connection exit, the riders rated it as a safe type;however, the data showed higher average crash frequency and rate than those at diamond exits or directional exits. The possible reason could be the unexpected curvature in the middle of the ramp, which could be dangerous if the rider is not familiar with the exit ramp location or doesn’t pay attention to the ramp curvatures. The crash predictive model was developed, and the result indicated that if all remained the same, a directional exit, a loop exit, or an outer connection exit will have 16%, 27%, and 42% more crashes than a diamond exit, respectively. The findings from this study can help policy-makers and engineers to develop and apply effective countermeasures to reduce motorcycle crashes and injury severity levels for different exit ramp types.

Factors Affecting Arab Goat Flock Dynamics in Western Lowlands of Ethiopia

The study was conducted to estimate flock dynamics of western lowland Arab goat and to assess their contribution to income of smallholder farmers in Kurmuk and Assosa districts, western Ethiopia. Flocks of 30 households were monitored for a period of 12 months in 2016. Data were analyzed using the general linear model procedure of SAS and two-way interaction effects were fitted in the model and retained when found significant in the preliminary analysis. The study result indicates that total entrances for all flock were significantly (p < 0.05) higher in dry and hot-cool seasons than wet season. Most of the entrance was kids born in hot-cool season (January) (4.0 ± 0.42) and hot-dry season (May) (5.4 ± 1.09) for Assosa and Kumruk study sites, respectively. Kid mortality constituted the greater part of outflow. High kid mortality was occurred during July, February, January, and September. Most of the sell of castrated goats were occurred in September and April for both small and large flocks targeting holidays celebrated during this months. Male goat owners had significantly lower goat production potential (GPP) value than female (0.47 ± 0.02 vs. 0.52 ± 0.02). The GPP was lower in small flock than in large flock (0.48 ± 0.02 vs. 0.51 ± 0.02). Higher GPP was recorded in the months of January, February, and March for both large and small flocks. The off-take was higher (P < 0.05) in Assosa (0.06 ± 0.01) than Kumruk (0.02 ± 0.02) district. The average goat production efficiency (GPE) was higher (P < 0.05) in Assosa large (193.23 ± 20.0) and small flocks (93.44 ± 17.3) than Kumruk large (84.71 ± 15.6) and small flocks (33.33 ± 26.3).The production efficiency recorded was not comparable to the potential that the farmers had to sell goats or consume goats’ meat and milk. The lower goat production potential observed for small flocks implies that high mortality rates severely restrict receiving higher benefits from goat. Therefore, in order to optimize the productivity of goats flock dynamics, developing health intervention strategies that target reduction of kids’ mortality is imperative.

盾构隧道进出洞施工渗漏诱发结构倒塌试验研究

为明确隧道进出洞施工时因渗漏而诱发的结构倒塌发展过程,设计并开展缩尺模型试验。根据相似关系设计模型试验,制作模型土体与模型盾构隧道。参考实际进出洞施工渗漏事故案例,触发模型盾构隧道渗漏,在模型箱内重现隧道结构倒塌的全过程,并观测事故发展过程中的地层响应、隧道外部土压力变化、隧道倒塌发展过程。通过分析隧道进出洞施工中不同位置发生渗漏后结构的倒塌响应,对比不同位置渗漏对隧道进出洞施工致灾发展过程的影响。试验研究发现:1)隧道进出洞施工发生渗漏后,外部土体由于渗流侵蚀产生不稳定土洞,土洞经历了形成—失稳—再现的循环过程;2)隧道结构倒塌是由不稳定土洞失稳坠落冲击隧道结构导致的;3)隧道顶部和腰部2种不同位置渗漏后外部土体侵蚀发展的本质相同,但是不同渗漏位置产生的土洞形状有明显差异,导致最终隧道倒塌位置有所差异。

基于主线密度预测的快速路入口匝道控制方法

针对快速路入口匝道区域拥堵问题,本文提出一种基于交通密度预测的入口匝道控制方法。通过分析快速路匝道区域的交通特性,定义交通流缓行状态,利用经典宏观交通流模型对快速路主线的历史密度进行统计,基于速度、密度参数进行聚类分析量化缓行状态交通参数特征。基于城市交通流的日变化特性,利用时间序列模型对交通密度进行短期预测,基于预测结果识别缓行状态。针对交通缓行状态,提出一种快速路主线交通密度与入口匝道排队长度的协同控制模型,通过控制入口匝道进而控制主线下游密度不超过临界密度,利用PSO-PID(Particle Swarm Optimization-Proportional Integral Derivative Control)算法对控制模型进行求解。以南昌市洪都大道快速路为例,对晚高峰缓行时段进行仿真分析,并与经典的匝道控制方案进行对比分析。结果表明:本文模型相较ALINEA模型,将匝道调节率提高11.0%,匝道平均排队长度和平均延误分别降低了14.8%和13.5%。

基于POI的TOD项目设计策略研究

POI是“Point of Interest”的缩写。每个POI包含四方面信息,名称、类别、坐标、分类,文章拟通过对地面空间和地下空间两个维度的用地构成、建筑类型与使用功能的研究分析,尝试探索基于POI的旧城核心区地铁站出入口设置的量化设计方法。文章通过文献研读、类比分析等研究手段,对国内外地铁站出入口设置进行了梳理与分析,弥补了旧城核心区地铁站出入口量化设置研究的理论空白,为国内类似项目提供了一定的设计研究素材。

上海地铁运营车站出入口底板改造防水技术探讨

上海地铁运营线网中,有为数不少的车站出入口缺少下行自动扶梯,根据相关部门要求,上海地铁已开展了一部分出入口的加装扶梯改造,并计划未来几年覆盖全网;加装扶梯过程中,有部分出入口需要局部开挖结构底板增设扶梯基坑,施工风险较大。以此类涉及出入口改造项目为例,介绍运营车站出入口底板改造中的防水关键技术,以期为今后同类型改造项目的防水设计提供借鉴。

大断面矩形顶管下穿管线MJS加固效果研究

郑州地铁3号线某车站8号出入口采用大断面矩形顶管施工,近距离垂直下穿DN2000污水管线,采用MJS工法对污水管线底部土体进行加固,对顶管过程的地表和管线位移进行实时监测,通过对比数值模拟和实测结果,验证数值模型的准确性和MJS管底土体加固措施的可行性。通过三维数值计算得出:采用MJS加固后的地表沉降、管线竖向位移、横向水平位移、弯矩和剪力比未加固土体分别减小53.59%、38.13%、73.3%、57.3%和48.02%,MJS能够明显提高管底土体承载力、密实度、强度和弹性模量,起到固定和保护管线的作用;进一步分析MJS的注浆置换率、加固宽度、加固深度对管线变形的影响,并给出置换率、加固宽度和加固深度建议值,为类似工程提供参考和借鉴。

400km/h高铁隧道出入口缓冲结构开口率对微压波影响研究

随着高速列车运行时速的提升,车-隧气动效应加剧、微压波超限问题愈发严重。以往研究表明,隧道洞口设置缓冲结构是解决微压波问题的有效手段之一,但是随着隧道长度增加、列车时速提升,仅以入口缓冲结构作为标准的设计方法存在一定局限性。并且国内外的研究重点更多集中在入口缓冲结构,对出口缓冲结构及隧道出入口均设置缓冲结构的设计方法研究相对较少。针对这一问题,利用控制容积法分析出口开口式缓冲结构的关键影响参数。基于LES湍流模型和动网格技术建立三维数值仿真模型,对关键参数的正确性做出验证。分析隧道出入口对称、非对称设置缓冲结构对微压波特性的影响,提出适用于单线和双线隧道的洞口开口式缓冲结构的设计方法。研究结果表明:1)隧道出口缓冲结构开口率是影响出口缓冲结构对微压波压力缓解效率的关键参数,开口率越大,微压波压力最大值越低;2)隧道入口以压力梯度为控制标准设置最优缓冲结构、隧道出口提高缓冲结构开口率的形式,在单线隧道缓冲结构设计中对微压波有更高的缓解率,出口缓冲结构开口率越大,对微压波压力缓解效率越高;3)双线隧道洞口开口式缓冲结构设计时,应当增加其总开口率,同时选择小面积、多个数的开口形式并在隧道出入口对称设置。

V2X环境下基于圆风险域的交通冲突识别模型

为提高快速路匝道区域合流冲突的识别精度,并缓解合流冲突提供决策依据,提出一种V2X(vehicle to everything)环境下基于圆风险域的交通冲突识别模型.通过V2X技术实时获取车辆位置和速度,以冲突风险时间为关键参数,分析主线车辆和匝道车辆的不同运动状态特性;引入风险域概念,结合车辆运动学,构建基于圆风险域冲突识别模型,进而通过两圆的位置关系表征两车之间的运动关系,实现交通冲突的识别;为细化冲突风险程度,采用累计频率曲线法判定冲突风险程度等级.仿真结果表明,采用冲突识别模型的识别率相比未采用时提高25.81%,说明该模型能有效识别匝道合流冲突,提高通行效率,并可为V2X环境下匝道合流车辆提供安全预警.

基于混合策略改进ASO-LSSVM的风险驾驶行为分类识别

为解决现有智能算法在优化支持向量机识别风险驾驶行为过程中收敛速率缓慢和误差较大的问题。首先,采用Tent映射取代原子搜索优化算法(ASO)种群初始化随机设置的方式,增加原子种群多样性和质量;其次,使用逐维小孔成像反向学习与柯西变异混合机制,提高原子个体择优位置的多样性,克服ASO算法易陷入局部最优和过早收敛的问题;最后,通过引入自适应变螺旋搜寻策略改进原子个体位置更新过程,以提升ASO算法的全局搜索能力,实现全局搜索和局部开发间关系的有效平衡,缓解ASO算法易陷入局部最优和收敛精度不足的问题。以上海北横通道出口匝道车辆轨迹数据为输入,使用混合策略改进ASO算法寻优求解最小二乘支持向量机(LSSVM)参数,构建基于混合策略改进原子搜索优化最小二乘支持向量机IASO-LSSVM的快速路出口匝道风险驾驶行为分类识别模型。数值仿真实验结果表明:IASO算法在12个基准测试函数数值仿真结果的平均值、标准差、最佳适应度和最差适应度等方面均更接近最佳优化值。IASO-LSSVM模型相较于ASO-LSSVM和LSSVM等模型的风险驾驶行为分类识别结果误差指标正确率、精确率、召回率和F1值分别增加11.5~24.5、14.1~29.0、15.1~28.6和14.7~31.2个百分点,且在不同类型风险驾驶行为识别结果中误差变化范围最小。IASO算法参数寻优求解精度和收敛速率优于ASO算法,且IASO-LSSVM模型可用于不同类型风险驾驶行为精准识别,可为车辆行驶轨迹状态合理判别,制定风险驾驶行为预警防控措施提供数据支撑与理论依据。

城市轨道交通车站出入口分布式光伏发电应用研究

[目的]基于我国“碳达峰、碳中和”目标,以及城市轨道交通绿色、低碳、可持续发展的需求,研究分布式光伏发电系统在车站出入口应用的可行性。[方法]以深圳地铁为例,结合车站出入口的造型,研究了车站出入口光伏建筑一体化方案和光伏系统并网方案,分析了车站出入口光伏发电系统的经济效益和社会效益。[结果及结论]车站出入口是应用分布式光伏发电系统的理想场地,各类车站出入口结构形式均具备应用光伏发电技术的条件。城市轨道交通线路众多,每条线路车站出入口数量超过百余个,随着光伏发电成本进一步降低及国家“双碳”目标的推动,“光伏+轨道交通”将会产生更大的经济效益和显著的社会效益。

基于心率变异性的高密度立交出入口驾驶人精神负荷特性

互通式立交承担着不同方向交通流的流向转换功能,是道路交通网络的重要节点。目前高密度立交在城市道路网络中已愈发常见,高密度立交之间的间距比普通立交更小,车辆交织更为密集,驾驶人需要在更短的时间内进行分合流驾驶操作。为探究立交间距对驾驶人精神负荷的影响与高密度立交出入口区段的驾驶人精神负荷统计特性,在重庆市内环快速路上选择了1段包含4座连续立交的路段作为实验对象,其中3座立交为高密度立交。通过车载仪器采集47名驾驶人在实车实验过程中的心电数据,对在高密度立交出入口区段与普通间距立交出入口区段的驾驶人心率变异性时域和频域指标进行差异性分析,得到了驾驶人在高密度立交与普通间距立交出入口区段的精神负荷分布特征。研究结果表明:驾驶人在经过普通间距立交出入口区段和高密度立交出入口区段时的心率变异性时域指标不存在显著性差异,频域指标心率变异性的低、高频功率的比值(ratio of low-frequency to high-frequency,LF/HF)存在显著性差异,频域指标LF/HF可作为评价驾驶人精神负荷在立交出入口区段的主要指标;驾驶人在经过高密度立交入口区段时,频域指标LF/HF比经过普通间距立交入口区段时显著增加,立交间距不足会增加驾驶人在立交入口区段的精神负荷;驾驶人在经过普通间距立交出口区段时的心率变异性频域指标LF/HF比经过高密度立交出口区段时显著增加,即驾驶人通过普通间距立交出口区段的精神负荷更大;对于高密度立交群,驾驶人在入口区段的精神负荷水平要略高于出口区段。

高密度立交出入口车辆纵向运行特性

为明确车辆在高密度互通立交主线入口、出口以及连接段的纵向运行速度特征,在重庆市选取了5座立交为研究对象,开展了47名驾驶员的小客车实车驾驶试验。通过speedbox和mobileye等实验仪器采集的数据,包括车辆运行速度、纵向加速度等,对数据进行处理并按入口、出口及连接段分类提取数据,绘制出对应的速度曲线图,以明确车辆在高密度互通立交出入口以及连接段的纵向运行特性。分析结果表明:入口处速度趋势有两类,平行式入口是上升-平稳,直接式入口是持续上升,平行式入口速度均值高于直接式,平行式入口速度标准差小于直接式;不同类型入口对驾驶人的加速操作选择具有一定影响;平行式入口在纵向加速度均值上较直接式入口低;出口处速度分布整体呈平稳下降趋势,平行式的运行速度均值低于直接式,但速度标准差却更高;出口速度变化特征点受驾驶人在主线出口减速偏好性影响;平行式出口减速度最大值与均值均大于直接式;相邻立交净距较短时,连接段的速度变化较为平缓,并且不同驾驶人的速度幅值比较接近;而常规净距的相邻立交,连接段的速度波动性大且离散。研究成果为高密度互通立交出入口及连接段的安全性评价以及安全改善提供了理论支撑以及基础数据支撑。

基于HRI的高密度立交群出入口驾驶人精神负荷

为明确驾驶人在高密度互通立交出入口时精神负荷变化与驾驶环境的相关性,选取重庆市主城区内环快速路上4座立交(3座小净距立交及1座普通立交)作为研究对象,开展了47位驾驶人的实车驾驶试验。使用生理仪连续采集了驾驶人的心电数据,计算了驾驶人经过立交分流点、合流点前后的心率增长率(heart rate increase,HRI),以HRI作为驾驶人精神负荷评价指标,明确了驾驶人在立交出口和入口的精神负荷变化规律,对出口和入口的精神负荷进行了对比,并分析了环境熟悉程度及分流方向对驾驶人精神负荷的影响。结果表明:小净距立交出入口驾驶人HRI存在6种变化模式,较普通立交出入口存在的5种变化模式更多样化;小净距立交出口和入口的HRI均值变化呈相反的趋势,且HRI均值及特征分位值均表现为入口HRI略大于出口HRI;合流和分流行为都会使驾驶人的精神负荷产生明显波动;立交间距离过短,会导致驾驶人经过立交出口和入口时的HRI增大,精神负荷增加;环境熟悉程度对驾驶人经过立交出口和入口分合流点时的HRI存在显著影响,驾驶人第2、3次经过相同立交出口和入口时的HRI波动明显减小;驾驶人经过立交左侧分流点时的HRI较右侧分流点更高,精神负荷更大。