考虑非机动车影响的直线式单泊位公交停靠站设置优化

为了降低非机动车对沿人行道设置的公交停靠站周边交通的影响，对直线式单泊位公交停靠站设置进行优化。选取重庆市6个沿人行道设置的单泊位公交停靠站进行调研，分析非机动车车道宽度、公交车停靠站长度、当量交通量、非机动车速度等参数与3类冲突率(非机动车与公交车3种形态的追尾与横向冲突率)的相关关系，拟合得到回归方程。根据回归方程和相关性系数建立交通冲突预测模型，并对模型进行验证，预测模型误差均小于10%。研究表明:当非机动车道设置宽度在3.5~4.0 m、直线式单泊位公交停靠站设置长度在16~18 m时，3类冲突率最低。当量交通量达到700 pcu/h之后，冲突率趋于平稳；此时非机动车速度仍不宜大于6 m/s。选取2个公交车停靠站进行冲突率预测，并对其进行安全等级评价。以冲突率最低值作为约束条件，对沿人行道设置的直线式单泊位公交停靠站进行优化。研究成果可为公交停靠站周边区域的交通管理和规划设计提供理论依据。      

港湾式公交停靠站对路段通行能力的影响

在对南昌市城区主干道港湾式公交停靠站调查的基础上,通过 Vissim 仿真模拟得到大量交通流数据,从港湾式站台设置的长度、站台乘客等待数量、路段车道数、路段车辆的平均速度、站台停止车辆数、以及进出口平均延误时间6个方面建立神经网络分析模型,以路段平均延误车辆/路段实际通行能力作为通行能力的影响折减,运用 Matlab 软件编程求得变量因素与输出影响的连接强度权值 W 与偏置值 B ,为港湾式公交站对路段通行能力影响提供了定量化影响系数。      

Development of probabilistic pedestrian fatality model for characterizing pedestrian-vehicle collisions

Pedestrian-related accidents are considered to be the most serious of traffic accidents due to the associated high fatality rates. In Korea, pedestrian fatalities accounted for approximately 40% of all traffic-related fatalities in 2004. Significant efforts have been made to develop effective countermeasures for pedestrian-vehicle collisions. A basis for devising such countermeasures is to understand the characteristics of pedestrian-vehicle collisions. This study develops a pedestrian fatality model capable of predicting the probability of fatality in pedestrian-vehicle collisions. Binary logistic regression and a probabilistic neural network (PNN) are employed to estimate the probability of pedestrian fatality. Pedestrian age, vehicle type and collision speed are used as independent variables of the fatality model. The models developed herein are valuable tools that can be used to direct safety policies and technologies associated with pedestrian safety.     

非港湾式公交停车对道路交通流的影响分析

公交车进出站点不仅影响本身,也给其他车辆运行带来很大干扰。文章首先比较全面地分析非港湾式公交停车影响下道路交通流特征,然后借助于EXCEL软件,构建关于公交停车频率、公交停车时间、最大公交停车长度及其存在时间、道路流量的车速和车头时距多元线性模型,并进行了严格的数学检验。该研究为合理分析路段交通流状况、正确计算区间行驶车速与车头时距提供了依据。     

港湾式公交停靠站设置条件研究

针对城市道路中公交进出直线式与港湾式停靠站对外侧车道通行能力产生影响的问题,运用排队论与间隙接受理论相关成果,分别建立了直线式、港湾式排队无溢出及港湾式排队有溢出3种情况下公交进出停靠站对外侧车道的影响时间模型;在此基础上以公交出站延误及站点服务强度作为约束条件,推导出外侧车道通行能力计算模型,并给出设置条件;对仿真模拟试验结果与模型计算结果进行对比,并对模型适用性进行了检验,给出了不同公交到达率下3种模式设置港湾式公交停靠站的通行能力范围值。结果表明:该模型具有较高的精度和可靠性,能够为城市道路设计提供必要的参考依据。     

Injury analysis of pedestrians in collisions using the pedestrian deformable model

Vehicle safety has become the most important issue in automobile design. However, all efforts to improve safety devices focus on enhancing safety features for occupants. Notably, pedestrians are the second largest category of motor vehicle deaths, after occupants, and account for about 13 percent of motor vehicle deaths. It is essential to design pedestrian-friendly vehicles and pedestrian protection systems to reduce pedestrian fatalities and injuries. To effectively assess pedestrian injuries resulting from vehicle impact, a deformable pedestrian model must be developed for vehicle-pedestrian collision analysis. This study constructs a pedestrian-collision numerical model based on LS-DYNA finite element code. To verify the accuracy of the proposed deformable pedestrian model, experimental data are used in the pedestrian model test. This study applies the proposed model to analyze the dynamic responses and injuries of pedestrians involved in collisions. The modeled results can help assess vehicle pedestrian friendliness and assist in the future development of pedestrian-friendly vehicle technologies.     

What affects pedestrian crossing difficulty at urban intersections in a developing country?

In developing countries, road traffic crashes involving pedestrians have become a foremost concern. At present, road safety assessment plans and selection of interventions are primarily restricted to traditional approaches that depend on the investigations of historical crash data. However, in developing countries such as India, the availability, consistency, and accuracy of crash data are major concerns. In contrast, proactive approaches such as studying road users' risk perception have emerged as a substitute method of examining potential risk factors. An individual's risk perception offers vital information on probable crash risk, which may be beneficial in detecting high-risk locations and major causes of crashes. Since the pedestrian fatality risk is not uniform across the urban road network level, it may be expected that pedestrians' perceived risk measured in terms of “crossing difficulty” would also vary across the sites. In this perspective, the present paper establishes a mathematical association between the pedestrians' perceived “crossing difficulty” and actual crashes. The model outcome confirms that pedestrians' perceived crossing difficulty is a good surrogate of fatal pedestrian crashes at the intersection level in Kolkata City, India. Subsequently, to examine the impact of traffic exposures, road infrastructure, land use, spatial factors, and pedestrian-level attributes on pedestrians' “crossing difficulty”; a set of Ordered Logit models are developed. The model outcomes show that high vehicle and pedestrian volume, vehicular speed, absence of designated bus stop, the presence of inaccessible pedestrian crosswalk, on-street parking, lack of signalized control (for both vehicle and pedestrian), inadequate sight distance, land use pattern, slum population, pedestrian-vehicular post encroachment time, waiting time before crossing, road width, and absence of police enforcement at an intersection significantly and positively increase pedestrian's crossing difficulty at urban intersections. To end, the model findings are advantageously utilized to develop a set of countermeasures across 3E's of road safety.     

多线路公交停靠站停靠组织研究

针对多线路公交停靠站公交车辆进出站排队现象严重,站点延误大,运行效率低等问题,分析了不同停靠组织形式和不同主辅站设置类型对公交运营效率的影响。运用Vissim对3泊位直线式和港湾式公交停靠站点的顺序停靠组织和不同组合的划线停靠组织分别进行仿真研究,从公交延误、车辆总延误、行程时间以及通过车辆数4个方面对不同停靠组织形式在不同条件下的交通运行效果进行评价,得到不同形式公交停靠站的最佳停靠组织形式;在此基础上,对不同组合型式的6泊位主辅站停靠组织进行仿真评价,得到了最优的主辅站设置类型。仿真结果表明:对3泊位公交停靠站采用直线式停靠站,总延误平均降低38.4%,采用港湾式公交停靠站,总延误平均降低40.6%;对6泊位主辅站采用双港串联设置,总延误降低22.8%。      

单车道港湾式公交停靠站设置条件研究

公交进出停靠站对道路通行能力产生折减,运用排队论与间隙接受理论相关知识,对单车道公交停靠站上下限设置条件进行研究,分别建立了直线式、港湾式公交进出停靠站对机动车道的影响时间模型;进而以公交出站延误及站点服务强度作为约束,推导出机动车道通行能力及设置条件模型;最后对仿真试验结果与模型计算结果进行对比分析、模型的适用性进行检验,给出不同公交到达率下设置港湾式公交停靠站通行能力范围值。结果表明:当公交到达率为20 veh/h和30 veh/h时,对应的单车道港湾式公交停靠站设置的上下限条件分别为:518～1 262 veh/h、518～1 243 veh/h。可见,该模型具有较高的精度和可靠性,所得结果能够为城市道路设计提供必要的参考依据。     

基于优化模型的城市公交停靠站址的选择

通过分析影响公交停靠站站址选择的主要因素,综合考虑行人过街延误,和公交站点离交叉口距离限制,将公交站址依据路况进行分类研究,针对各类型建立了基于乘客平均出行时间最小的多条公交线路的停靠站位置的优化选择模型,并提出了该模型的求解算法。     

一种降低人-地撞击损伤的车辆制动控制方法

为降低车人碰撞事故中人与地面撞击所致损伤,提出一种车辆制动控制策略.该策略在检测到人体头部与车辆首次接触后松开车辆制动,之后依据若干准则再次完全制动车辆直到车辆停止.选择10种车型、两种制动方法(完全制动和控制制动)和一个虚拟仿真系统(包含3种车速×4种行人尺寸×2种行人步态)设计了共480次MADYMO仿真试验.结果...     

Safety benefits of integrated pedestrian protection systems

This study developed a methodology for evaluating the effectiveness of an integrated pedestrian protection system (IPPS) based on simulations. The proposed IPPS consists of active and passive vehicular systems for protecting pedestrians, including a pedestrian warning information system (PWIS), an active hood lift system (AHLS), and pedestrian airbag system (PAS). Two simulation methods were applied in the proposed methodology: a driving simulation and a finite element simulation. A driving simulator was used to obtain the change in collision speed, which is a key parameter for evaluating driving behavior when a PWIS is applied. In addition, a well-known simulator for finite element analysis, LSDYNA was used to simulate the impact of a pedestrian on a vehicle hood in a pedestrian-vehicle collision. The head injury criterion (HIC), which is an outcome of LS-DYNA simulations, is a major parameter for evaluating passive safety systems. The probability of pedestrian fatalities by collision speeds and HICs were estimated to quantify the safety benefits of an IPPS based on the statistical analyses. The results showed that an IPPS is capable of reducing pedestrian fatalities by approximately 90 % associated with jaywalking in the midblock and walking on the roadside. The findings of this study can be used to boost the development of various vehicular technologies for pedestrians. The results can be effectively used for policy making and deriving legislative requirements associated with advanced vehicular technologies for enhancing pedestrian safety.     

浅论新建城区公交停靠站设置形式及设置时机

随着各等级城市规模的扩大,公交停靠站的设置形式、设置时机需要相关决策部门仔细研究,才能体现停靠站应有的价值.通过对不同形式的停靠站的特点进行分析,提出了停靠站的设置时机.     

Design of emergency braking algorithm for pedestrian protection based on multi-sensor fusion

Globally, safety has become an increasingly important issue in the automotive industry. In an attempt to reduce traffic fatalities, UNECE launched a new EU Road Safety Program which aims to decrease the number of road deaths by half by 2020. AEB (Autonomous Emergency Braking) is a very effective active safety system intended to reduce fatalities. This study involves the design of a multi-sensor data fusion strategy and decision-making algorithm for AEB pedestrian. Possible collision avoidance scenarios according to the EuroNCAP protocol are analyzed and a robust pedestrian tracking strategy is proposed. The performance of the AEB system is enhanced by using a braking model to predict the collision avoidance time and by designing the system activation zone according to the relative speed and possible distance required to stop for pedestrians. The AEB activation threshold requires careful consideration. The test results confirm the advantages of the proposed algorithm, the performance of which is described in this paper.     

考虑信号优先的相邻公交停靠站最佳布置方法

首先建立了在离线信号配时方案下,单个车辆通过信号控制交叉口群的信号延误计算模型;进而以车均延误最小为目标,建立了停靠站最佳布置的选择模型。通过对优化模型解的分析表明,不同的信号协调配时方案对应不同的停靠站最佳布置方案,单点最优解的叠加并非是全局最优解。以两个交叉口和两个停靠站的实际案例进行计算分析,得出在信号优先协调控制方案下的停靠站最佳布置方案,最佳布置方案的下车辆延误明显低于其他方案。最后通过微观仿真软件VISSIM验证了模型的计算结果。     

考虑出行时间窗的定制公交线路车辆调度方法

为提高定制公交系统的运行效率,研究了带乘客出行时间窗约束的多条定制公交线路车辆调度方法。给出了乘客出行站点合并方法,将公交车早到、晚到站点所造成的乘客损失转变为当量运营里程,以多辆公交车总运营里程最小为目标,考虑乘客的站点约束、公交车容量约束以及乘客的出行时间窗,建立了定制公交车辆调度优化模型。其次分析了乘客出行起点、终点对模型求解的影响,通过提出虚拟源站点,将多辆定制公交车的调度问题转换为多旅行商问题;基于后向推导原则设计贪心算法求得模型的可行解;之后基于遗传算法,采用自然数编码机制,将每个站点作为基因位,按照访问次序排列成染色体对应问题的解;最后给出了贪心算法和遗传算法的流程。在理论研究的基础上以定制公交线路为例对建模过程和模型的求解过程进行了阐述。研究结果表明：所建立的优化模型能够输出合理的多条定制公交线路车辆调度方案,不仅可以给出每辆定制公交的途经站点、运营里程,还可以给出每个站点的准点程度以及由于公交早到、晚到折算得到的当量运营里程;在求解算法质量方面,与可行解相比,相对最优解输出的方案能够使综合运营里程降低10.4%;模型求解时间为30.3 s,可以满足定制公交企业的实时性需求。     

Modeling two-way stop-controlled intersection crashes with zero-inflated models on Louisiana rural two-lane highways

Intersection safety continues to be a crucial issue throughout the United States. In 2016, 27% of the 37,461 traffic fatalities on U.S. roadways occurred at or near intersections. Nearly 70% of intersection-related fatalities occurred at unsignalized intersections. At such intersections, vehicles stopping or slowing to turn create speed differentials between vehicles traveling in the same direction. This is particularly problematic on two-lane highways. Research was performed to analyze safety performance for intersections on rural, two-lane roadways, with stop control on the minor roadway. Roadway, traffic, and crash data were collected from 4148 stop-controlled intersections of all 64 Parishes (counties) statewide in Louisiana, for the period of 2013 to 2017. Four count approaches, Poisson, Negative Binomial (NB), Zero-inflated Poisson (ZIP) and Zero-inflated Negative Binomial (ZINB) were used to model the number of intersection crashes for different severity levels. The results indicate that ZIP models provide a better fit than all other models. In addition to traffic volume, larger curve radii of major and minor roads and wider lane widths of major roads led to significantly smaller crash occurrences. However, higher speed limits of major roads led to significantly greater crash occurrences. Four-leg stop-controlled intersections have 35% greater total crashes, 49% greater fatal and injury crashes, and 25% greater property damage only (PDO) crashes, relative to three-leg intersections.     

交通宁静化理念下公交站点处两轮车专用道一体化设计

两轮自行车、电动自行车和摩托车专用道一体化的改造方案是为解决城市中心摩托车和非机动车争夺路权带来的交通问题的一种探索和尝试。专用道的设置不可避免也要对公交车站进行改造，交通比较复杂。为有序引导站点处的交通流，保障乘客安全，首先介绍了路段两轮自行车、电动自行车和摩托车专用道一体化方案的改造原因和思路，然后结合城市交通宁静化理念，对直线式停靠站和港湾式停靠站处的专用道提出了几种设计方案，并分析其优缺点和用地条件。经过对比，推荐公交站点处采用曲线式两轮车专用道设计方案，最后还配套了一些交通宁静化措施。     

行人保护技术发展现状分析

汽车与行人碰撞过程中的行人保护问题一直是汽车安全技术发展的一个重要课题。基于国内外行人保护法规及行人保护技术的研究现状,以汽车被动安全性为研究对象,介绍了保险杠行人保护技术、发动机罩行人保护技术、行人保护气囊及其他行人保护技术。随着技术的不断进步,我国将越来越重视行人安全保护技术。该研究为我国后续行人保护研究提供了参考。     

社会车辆速度及靠站时间对城市客车排放能耗的影响

为定量探究不同运行区域下社会车辆速度和靠站时间对城市客车排放耗电水平的影响,以燃气和纯电动公交车为研究对象,收集了5条公交线路共75万多条GPS数据和大量的浮动车辆数据,建立不同运行区域下城市公交车运行工况预测模型及排放能耗预测模型,并进行定量影响分析.结果显示:在道路区域下,社会车辆速度相较靠站时间对公交车排放能耗的...