自动驾驶公交运行评价研究及应用现状

自动驾驶是智能汽车和智能交通发展的重要技术方向之一,而公交领域是自动驾驶技术能够落地的重要应用场景。目前,自动驾驶技术在城市客运场景下逐渐由产品测试、封闭测试逐步走向试运营、运营阶段。为了支撑公共汽电车自动驾驶研究,本文综述了自动驾驶技术及自动驾驶公交评价与测试现状,回顾了常规公交运行及服务质量评价维度和方法,归纳了自动驾驶车辆在车辆产品测试、封闭测试及开放道路测试的相关研究及评价方法。进一步指出,认识自动驾驶公交车辆应对开放的道路交通状况下的运营特征,并确定面向运营的技术适用条件,是投入社会市场应用与推广的前提。     

自动驾驶标准体系及测试发展路线分析

自动驾驶测试通常分为自主式和车路协同式两种技术路线;其中,自主式自动驾驶主要依靠自身传感器完成周围目标识别进而进行决策知行的实现方式;车路协同式自主驾驶则主要依靠车载单元和路侧单元直接的通信完成周边的信息收集,实现对周边环境感知并完成决策判断。目前的自动驾驶测试多集中在单一功能测试为主;同时,由于两种技术路线各有侧重;因此,测试标准各不相同,无法形成完成标准体系。本文拟对目前国内外的自动驾驶相关标准进行分析归纳,从场景要素识别、功能测试、协同式自动驾驶功能要求、车路信息交互安全要求、测试和管理要求进行分析;进而为L_3级以上自动驾驶全面测试提供依据,同时也能为自动驾驶测试场地的规划及测试主体等的管理要求提供了建设参考。     

基于培训教学的汽车驾驶培训模拟器训练场景内容研究

针对汽车驾驶培训模拟器训练场景缺乏统一规范和要求的问题,基于雨天、冰雪天、雾(霾)天等恶劣条件下驾驶,以及山区道路和高速公路驾驶的安全风险,结合教学大纲规定的模拟培训教学内容及教学目标,提出了相应训练场景涵盖的情景内容及要求,并梳理了构建训练场景的技术要点,确保训练场景的合规性、互动性和驾驶真实感。     

卡车驾驶室内污染您还要忍受下去吗?

<正>多数的卡车司机都处在污染重灾区。每天既要承受驾驶室内空气污染、噪音污染,更要承受恶劣的工地粉尘环境、尾气排放污染等等,开卡车就该无条件承受这些污染吗?驾驶室内的"无形杀手"其实车内空气环境的要求也是近几年狂热的话题,尤其在乘用车领域,驾驶室内强烈的刺鼻性气味无不"彰显"污染的存在,国家也在2012年制定实施《乘用车内空气质量评价指南》,引导用户在购车时了解车辆驾驶室内污染物含量。但对于卡车来说好像自动屏蔽了车内空气环境这项问题,卡车,由于其生产     

美国政府《联邦自动驾驶汽车政策》解读与探讨

自动驾驶汽车是当前最热门的技术领域,制定相应的发展政策必然受到政府、企业、消费者等相关各方的关注。本文介绍了美国政府发布的全球首个无人驾驶汽车政策文件——《联邦自动驾驶汽车政策》,其内容包括政策目的、自动驾驶等级定义,政策组成包括了自动驾驶汽车性能指南、统一的州政策、现行国家公路交通安全管理局监管法规工具、将来可采用的新监管工具,以及下一步工作。总结了政策成果,包括将安全监管作为核心,鼓励创新、建立规范的决策程序,以及政策困难。认为美国的自动驾驶汽车政策相关内容值得中国跟踪分析。     

无人驾驶客车来了!

正从没想过,无人驾驶与我们这么接近!2017年6月7日,在上海嘉定国际汽车城—中国首个国家级智能网联汽车试点示范区一周年庆典上,主管单位首次向外界公开展示截至目前国内最为先进的汽车智能网联成果。在特斯拉、VOLVO等一众乘用车中,一辆从外观上看来与普通巴士无差异的微循环巴士自动驾驶,引起60多位大众媒体的极大热情。"模拟城市道路寻迹行驶、自动避过障碍、自动实现环岛绕行、到站自动停靠、自主变道",在无人驾驶的情况下,     

轨道交通列车制动系统离散性造成ATO停车精度问题的分析及解决

轨道交通信号系统采用基于通信的列车自动控制系统,列车根据实时的移动授权距离进行ATO驾驶。介绍了从列车制动系统时间和离散性的角度,对具有不同离散性的列车制动系统由于同一ATO控制命令响应偏差造成的ATO停车精度不准的问题,分析了ATO模式停车精度的优化设计,并在实际运营线路上进行了测试验证。测试结果表明,当遵守设计约束和改变ATO相关参数时,列车的停车精度得到了较大的提高。     

威伯科亮相IAA 2016 彰显商用车智能化技术新水平

正亮相IAA 2016,展示先进商用车智能化技术2016年9月21至9月29日,全球领先的致力于提高商用车安全、效率和智能互联技术的供应商威伯科在德国汉诺威举办的2016年IAA商用车展亮相,展示了业界领先的最新商用车技术方案。几十年来,威伯科已经通过其业界领先的安全和效率技术,为商用车实现自动驾驶奠定了基础,如电子制动系统、电子稳定控制系统、气制     

自动驾驶应同步重视技术发展与立法监管

正随着汽车产业的发展,汽车智能化与自动驾驶越来越受到关注。自动驾驶技术在提升驾驶安全性、减少事故发生率、减轻司机负担方面有着相关优势。目前,自动驾驶汽车技术逐渐进入早期实用化阶段,国内汽车行业对于自动驾驶技术的关注和重视也在逐步提升,部分企业已经在汽车智能化和自动驾驶上开始进行尝试,相关法律法规与监管措施如何跟上产业发展需求也已开始提上日程。     

中航爱维客:冲击中高端商务车市场尽显心机

<正>2015年4月20日,第16届上海国际车展上开幕后,某热门汽车网站评出了车展八款"最豪华最有逼格的神一样的客车",中航爱维客与奔驰自动驾驶概念车等七款轿车共同位列其中。作为全新的客车品牌,中航爱维客商务客车是身居制造业高端领域的中航工业以20余年汽车制造经验和技术沉淀自主研发的新产品,这款车既融入了航空特色又具有乘用车品     

The effect of the competition between cars and trucks on the evolution of the motorway transport system

Motorways, which were devised at the beginning of their history as dedicated roads intended to be traveled by cars only, are at present also traveled by considerable flows of trucks. This fact has deeply changed the motorway transport system with respect to its original conception, owing to the interactions between two categories of vehicles whose characteristics are very different. These interactions greatly increase the transport cost perceived by car drivers with respect to truck drivers. This paper studies the consequences of this cost asymmetry on the evolution of the transport system when the geometric characteristics of a motorway remain unchanged in time, while transport demand increases. By using a theoretical model of competition between cars and trucks, it is shown that, if both the geometric characteristics of a motorway and the increase rate of the activities that feed the transport demand remain unchanged over time, the competition between cars and trucks, as well as the fact that in general passengers have better transport alternatives than freight, make the increase rate of truck traffic greater than that of cars, causing a progressive increase in the proportion of trucks in the time periods in which a motorway is traveled by both the vehicle categories. Since truck traffic on motorways, at least in Europe, is very scarce on weekends and in holiday periods, in which motorways are traveled almost only by cars, these results seem to indicate a tendency to the specialization of motorways, which are likely to be used in the future mostly by only one category of vehicles in different periods of time.     

Delay-based passenger car equivalents for trucks at signalized intersections

This paper presents a new methodology for computing passenger car equivalents at signalized intersections that is based on the delay concept. Unlike the commonly used headway-based methods that consider only the excess headway consumed by trucks, the delay-based approach fully considers the additional delay heavy vehicles cause on traffic stream. Delay-based passenger car equivalents are not constant, but depend on traffic volume, truck type and truck percentage. The field data indicated that the passenger car equivalents increase as the traffic volume and the percentage of heavy vehicles increase. The field data were used to calibrate TRAF-NETSIM simulation model that was used to cover a broad range of traffic conditions. Mathematical models to estimate the equivalencies were developed. The passenger car equivalent for single unit trucks vary from 1.00 to 1.37, and for combination trucks 1.00–2.18 depending on traffic volume and truck percentage. The passenger car equivalents are highly correlated with traffic volume and, to some degree, with percentage of heavy vehicles. Although the PCE of 1.5 recommended in the 1985 HCM seems to be more reasonable than the 2.0 recommended in the 1994 and 1997 HCM, both overestimate the impact of single unit trucks. For combination trucks, the 1997 HCM overestimates the capacity reduction effects of the trucks in most cases.     

Preferences for autonomous and alternative fuel-powered heavy-duty trucks in Germany

Germany is by far the largest contributor of greenhouse gas emissions in the European Union but adopted its own climate action plan to achieve greenhouse gas neutrality by 2050. The country’s third-largest emitter of greenhouse gas emissions is the transportation sector. As of January 2019, 99.7% of heavy-duty trucks registered in Germany run on diesel while the share of alternative fuel-powered passenger cars increases steadily. Apart from rising emissions, the industry faces a growing shortage of qualified truck drivers. A solution to increasing emissions and the shortage of drivers are autonomous and alternative fuel-powered heavy-duty trucks. We employed a choice-based conjoint analysis with employees from freight companies in Germany to find out how they assess the main attributes of innovative trucks. Our results reveal that the maximum driving range is the most important attribute followed by the refueling/recharging time. Tank-to-wheel emissions, on the other hand, was ranked as the least relevant attribute. Moreover, we present customers’ preference shares for future heavy-duty trucks until 2035. According to our results, freight companies are generally open to switching from conventional to low emission and (conditionally-) automated heavy-duty trucks, however, a close collaboration between truck manufacturers, customers, infrastructure companies, and policymakers is essential to spur the penetration of autonomous and alternative fuel-powered heavy-duty trucks.     

Optimal tolls for multi-class traffic: Analytical formulations and policy implications

This paper puts together an analytical formulation to compute optimal tolls for multi-class traffic. The formulation is comprised of two major modules. The first one is an optimization component aimed at computing optimal tolls assuming a Stackelberg game in which the toll agency sets the tolls, and the equilibrating traffic plays the role of the followers. The optimization component is supported by a set of cost models that estimate the externalities as a function of a multivariate vector of traffic flows. These models were estimated using Taylor series expansions of the output obtained from traffic simulations of a hypothetical test case. Of importance to the paper is the total travel time function estimated using this approach that expresses total travel time as a multivariate function of the traffic volumes. The formulation presented in the paper is then applied to a variety of scenarios to gain insight into the optimality of current toll policies. The optimal tolls are computed for two different cases: independent tolls, and tolls proportional to passenger car equivalencies (PCE).The numerical results clearly show that setting tolls proportional to PCEs leads to lower values of welfare that are on average 15% lower than when using independent tolls, though, in some cases the total welfare could be up to 33% lower. This is a consequence of two factors. First, the case of independent tolls has more degrees of freedom than the case of tolls proportional to PCEs. Second, tolls proportional to PCEs do not account for externalities other than congestion, which is likely to lead to lower welfare values.The analytical formulations and numerical results indicate that, because the total travel time is a non-linear function of the traffic volumes, the marginal social costs and thus the optimal congestion tolls also depend on the traffic volumes for each vehicle class. As a result of this, for the relatively low volumes of truck traffic observed in real life, the optimal congestion tolls for trucks could indeed be either lower or about the same as for passenger cars. This stand in sharp contrast with what is implied in the use of PCEs, i.e., that the contribution to congestion are constant. This latter assumption leads to optimal truck congestion tolls that are always proportional to the PCE values.The comparison of the toll ratios (truck tolls divided by passenger car tolls) for both observed and optimal conditions suggests that the tolls for small trucks are about the right level, maybe a slightly lower than optimal. However, the analysis of the toll ratio for large trucks seems to indicate a significant overcharge. The estimates show that the average observed toll ratio for large trucks is even higher than the maximum optimal toll ratio found in the numerical experiments. This suggests that the tolls for large trucks are set on the basis of revenue generation principles while the passenger car tolls are being set based on a mild form of welfare maximization. This leads to a suboptimal cross-subsidization of passenger car traffic in detriment of an important sector of the economy.     

Heavy commercial vehicles‐following behavior and interactions with different vehicle classes

This work investigates the effect of heavy commercial vehicles on the capacity and overall performance of congested freeway sections. Furthermore, the following behaviors of heavy commercial vehicles and its comparison with passenger cars are presented. Freeways are designed to facilitate the flow of traffic including passenger cars and trucks. The impact of these different vehicle types is not uniform, creating problems in freeway operations and safety particularly under heavy demand with a high proportion of heavy vehicles. There have been very few studies concerned with the traffic behavior and characteristics of heavy vehicles in these situations. This study draws on extensive data collected over a long stretch of freeway using videotaping and surveys at several sites. The collected data were firstly used to study the interaction between heavy vehicles and passenger cars. Through a detailed trajectory analysis, the following behaviors of 120 heavy vehicles were then analyzed to provide a thorough understanding of heavy vehicles‐following behavior mechanism. The results showed a significant difference in the following behavior of heavy vehicles compared with other vehicles. Copyright © 2011 John Wiley & Sons, Ltd.     

Characteristics of truck traffic in Singapore

This paper presents the results of a project conducted to study the characteristics of truck traffic in Singapore. Detailed traffic surveys recording counts of vehicles by axle-configuration were performed at 219 sites over a period of nearly two years. The surveys covered 5 different road classes, namely expressways, arterials, collectors, industrial roads and local roads. It was found that the time distribution of truck travel were not the same among the five road classes. The peaking characteristics of truck traffic were less pronounced compared to passenger car traffic. The peak hour truck volume varied from 67.0% to 9.7% of the daily truck traffic as compared to 13.8% for passenger car traffic. The lane distribution pattern of truck traffic was studied in detail by road class, and was found to be a function of total directional traffic volume, total directional truck volume and the number of traffic lanes. Composition analysis was also carried out to study the lane use characteristics of single- and multiple-unit trucks.     

Dynamic charging infrastructure deployment for plug-in hybrid electric trucks

Inspired by the rapid development of charging-while-driving (CWD) technology, plans are ongoing in government agencies worldwide for the development of electrified road freight transportation systems through the deployment of dynamic charging lanes. This en route method for the charging of plug-in hybrid electric trucks is expected to supplement the more conventional charging technique, thus enabling significant reduction in fossil fuel consumption and pollutant emission from road freight transportation. In this study, we investigated the optimal deployment of dynamic charging lanes for plug-in hybrid electric trucks. First, we developed a multi-class multi-criteria user equilibrium model of the route choice behaviors of truck and passenger car drivers and the resultant equilibrium flow distributions. Considering that the developed user equilibrium model may have non-unique flow distributions, a robust deployment of dynamic charging lanes that optimizes the system performance under the worst-case flow distributions was targeted. The problem was formulated as a generalized semi-infinite min-max program, and a heuristic algorithm for solving it was proposed. This paper includes numerical examples that were used to demonstrate the application of the developed models and solution algorithms.     

Evaluation of fuel cell auxiliary power units for heavy-duty diesel trucks

A large number of heavy-duty trucks idle a significant amount. Heavy-duty line-haul truck engines idle about 20–40% of the time the engine is running, depending on season and operation. Drivers idle engines to power climate control devices (e.g., heaters and air conditioners) and sleeper compartment accessories (e.g., refrigerators, microwave ovens, and televisions) and to avoid start-up problems in cold weather. Idling increases air pollution and energy use, as well as wear and tear on engines. Efforts to reduce truck idling in the US have been sporadic, in part because it is widely viewed in the trucking industry that further idling restrictions would unduly compromise driver comfort and truck operations. The auxiliary power units (APUs) available to replace the idling of the diesel traction engine all have had limited trucking industry acceptance. Fuel cells are a promising APU technology. Fuel cell APUs have the potential to greatly reduce emissions and energy use and save money. In this paper, we estimate costs and benefits of fuel cell APUs. We calculate the payback period for fuel cell APUs to be about 2.6–4.5 years. This estimate is uncertain since future fuel cell costs are unknown and cost savings from idling vary greatly across the truck fleet. The payback period is particularly sensitive to diesel fuel consumption at idle. Given the large potential environmental and economic benefits of fuel cell APUs, the first major commercial application of fuel cells may be as truck APUs.     

Profit maximization by a private toll road with cars and trucks

This paper examines the profit maximizing behavior of a private firm which operates a toll road competing against a free alternative in presence of cars and trucks. Trucks differ from cars in value of time (VOT), congestion externality, pavement damage, and link travel time function. We find that the firm takes either a car-strategy or a truck-strategy for profit maximization. For a traffic mix with relatively large car volume and small truck volume, the car-strategy results in no trucks using the toll road, while the truck-strategy results in all trucks using the toll road. We derive the equilibrium flow pattern under any combination of car-toll and truck-toll, based on which we identify a profit-maximizing frontier and a strategy-switching frontier in the car-toll and truck-toll two-dimensional space. By geometrically comparing the two frontiers, we establish general conditions under which each strategy will be taken, which suggest that the truck-to-car VOT ratio, the total traffic demand, and the difference in travel distance between the two roads are critical in shaping the firm's strategy.     

Truck platooning on uphill grades under cooperative adaptive cruise control (CACC)

This paper examines CACC truck platooning on uphill grades. It was found that the design of CT policy should consider the effects of low crawl speeds on significant upgrades. Three simple solutions, which have different impacts on traffic flow efficiency, are proposed. Furthermore, truck platoons, controlled by a state-of-the-art CACC model, become asymptotically unstable beyond some critical grade. The errors are permanent, suggesting that trucks fail to re-engage after the upgrade. This occurs by complex interactions between the CACC control and the bounded acceleration capabilities of trucks. New control concepts are developed to complement the existing control model and achieve asymptotic (and string) stability. The instability mechanisms and new control concepts are not specific to the control model used.