Reducing the risk of rear-end collisions with infrastructure-to-vehicle (I2V) integration of variable speed limit control and adaptive cruise control system

Objective: Adaptive cruise control (ACC) has been investigated recently to explore ways to increase traffic capacity, stabilize traffic flow, and improve traffic safety. However, researchers seldom have studied the integration of ACC and roadside control methods such as the variable speed limit (VSL) to improve safety. The primary objective of this study was to develop an infrastructure-to-vehicle (I2V) integrated system that incorporated both ACC and VSL to reduce rear-end collision risks on freeways.

Methods: The intelligent driver model was firstly modified to simulate ACC behavior and then the VSL strategy used in this article was introduced. Next, the I2V system was proposed to integrate the 2 advanced techniques, ACC and VSL. Four scenarios of no control, VSL only, ACC only, and the I2V system were tested in simulation experiments. Time exposed time to collision (TET) and time integrated time to collision (TIT), 2 surrogate safety measures derived from time to collision (TTC), were used to evaluate safety issues associated with rear-end collisions. The total travel times of each scenario were also compared.

Results: The simulation results indicated that both the VSL-only and ACC-only methods had a positive impact on reducing the TET and TIT values (reduced by 53.0 and 58.6% and 59.0 and 65.3%, respectively). The I2V system combined the advantages of both ACC and VSL to achieve the most safety benefits (reduced by 71.5 and 77.3%, respectively). Sensitivity analysis of the TTC threshold also showed that the I2V system obtained the largest safety benefits with all of the TTC threshold values. The impact of different market penetration rates of ACC vehicles in I2V system indicated that safety benefits increase with an increase in ACC proportions.

Conclusions: Compared to VSL-only and ACC-only scenarios, this integrated I2V system is more effective in reducing rear-end collision risks. The findings of this study provide useful information for traffic agencies to implement novel techniques to improve safety on freeways.     

Driver-training and emergency brake performance in cars with antilock braking systems

The purpose of this study was to assess the effects of a two-day post-license driver-training program on brake performance in cars with antilock braking systems (ABS). A trainee group (n = 26) and a control group (n = 13) participated in the experiment. The trainee group were enrolled in a two-day training course that included instruction in a braking technique that may be used in cars with and without ABS. All participants performed emergency brake tests from 80 and 100 km h⁻¹ in an instrumented car before and after the training period. Results indicated the post-training group used a smoother braking profile, were less reliant on ABS activation, had enhanced postural stability, but took about one car length longer to stop from 100 km h⁻¹ compared with the control group. Implications of these results for braking in cars with and without ABS, and for driver education programs in general are discussed.     

汽车防抱死制动系统性能的研究

汽车防抱死制动系统的性能直接关系到汽车的运行安全,笔者以获得汽车制动最佳效能并能自动适应路况变化为控制系统的设计目标;通过分析车轮制动的动力学原理;运用自寻最优控制理论;进行了基于路面附着系数的汽车防抱死制动系统设计.仿真实验结果表明:该控制系统能充分利用最大附着力制动、实现自动路面识别并可提高汽车制动时的操作稳定性;进而证实了基于路面附着系数的汽车防抱死制动自寻最优控制方法,相对以往的控制方法更为简单和更适合于实际应用.     

自适应巡航控制系统对驾驶安全性的影响研究

为探究自适应巡航控制(ACC)系统对驾驶安全性的影响,首先通过实际道路驾驶试验获取我国典型道路交通场景,用驾驶模拟器进行场景仿真,并在有/无ACC状态下开展模拟驾驶试验;然后分析ACC系统在中国典型道路中的表现,通过对比分析ACC模式下不同特征驾驶人的碰撞时间(TTC),探讨不同类型驾驶人的应急反应。结果表明,ACC能较好地处理大多数路况;但面对危险路况时,不管是哪种类型的驾驶人,ACC的应急反应都没有手动驾驶迅速;且女性、年老和对ACC认知度低的驾驶人更容易受ACC的不良影响;驾驶人对ACC的认知度决定其ACC驾驶的安全性。     

Effect prediction of time-gaps for adaptive cruise control (ACC) and in-vehicle tasks on bus driver performance

Researchers have devoted a great deal of attention to the effects of driver assist systems on driver performance. This article describes a modeling approach to simulate the effects of time-gaps for adaptive cruise control (ACC) and manual in-vehicle tasks on bus-driver performance. A concept model was built with the knowledge of modularization, parameterization, and parallel processing. By running the model, the predictions for the effects of five levels of time-gaps and two types of in-vehicle tasks were collected in three measures: (1) mean gap, (2) minimum gap, and (3) collision rate. The model performed well in prediction, especially when driving with in-vehicle tasks. Predictions from the model were validated by the experiment with a verified fixed-base bus-driving simulator, used in the authors’ previous studies. Throughout the modeling approach, this research provides a theoretical and accurate way to assess effects of time-gaps and vehicle-equipped interfaces. In follow-up research, the authors will apply this approach to evaluate other driving assist systems (e.g. collision warning systems and navigation systems) to create a customized software kit.     

重大事故的应急救援预案编制技术

重大应急预案编制是安全生产的一项重要基础工作,对于提高应急救援能力,控制事故与灾害的恶化,保障人民安全具有重大意义.笔者从应急预案编制的技术层面上,论述了应急预案的基本框架和应急预案体系;认为该体系可以由6个一级和20个二级的核心要素构成.其中,应急策划是制定应急预案的技术基础,包括风险评价、资源分析和法律法规要求3个二级要素;应急准备包括机构与职责、应急设备设施与物质、应急人员培训、预案演练、公众教育和互助协议6个二级要素;应急响应是应急预案中核心的内容,包括现场指挥与控制等11个二级要素.所提出的应急救援预案文件体系,建议一般按照四级文件形式的设想,应急预案的目标是提高整体应急能力;建议把应急预案的具体编制过程划分为6个基本的步骤,对于预案编制与实施应实现持续改进的机制.     

汽车辅助制动装置发展综述

平均行驶速度和载重量的增加,要求车辆具有更大的制动效能,为了有效分流制动负荷常采用辅助制动系统.介绍国内外制动法规的发展和现状,排气辅助制动装置、发动机缓速器、电涡流缓速器和液力缓速器的结构、工作原理及各辅助制动装置的制动性能;比较各辅助制动装置的优缺点,有利于汽车制动技术的发展,全面提高汽车行驶安全性能;展望未来汽车辅助制动装置的两大发展趋势,一是电子控制技术在汽车制动上的应用,二是多种辅助制动装置的联合制动.     

重大工业隐患的地域监控体系研究

系统地分析了重大工业危险源与事故隐患;研究了地域监控、预警、应急预案的体系建设以及隐患监控的新技术应用基础;提出了职业安全卫生监控体系中的工业危险源和隐患监控。笔者认为：应该分为过程安全监控和安全目标监控两个层次。     

基于行人横穿场景的AEB触发宽度优化研究

为研究自动紧急制动(AEB)系统控制策略中触发宽度对行人横穿场景结果的影响,利用自动驾驶仿真软件PreScan建立道路及车辆模型,在Matlab模型控制平台Simulink中设计AEB纵向控制算法,模拟行人横穿危险场景,不断调整触发宽度,观察碰撞结果。结果表明:当汽车速度处于30～50 km/h时,系统触发宽度为1.75 m,能够起到很好的避撞效果;当汽车速度处于50～80 km/h 时,触发宽度需随行人速度增加而增加;触发宽度越宽,汽车接收信息越多, AEB误作用概率增大,故将最大触发宽度设置为3.5 m;当汽车速度处于60～80 km/h时,需同时优化触发宽度值和全力制动提前时间的长短,才能避免碰撞。     

建立突发公共事件应急机制的探讨

本文根据我国目前公共安全的现状、问题与经验,提出了建立健全应急机制的指导思想和工作原则,并根据突发公共事件的分类、分级,探讨了建立和完善突发公共事件的应急体制、机制和法制的途径和方法.     

Ensuring emergency planning & response meet the minimum Process Safety Management (PSM) standards requirements

When incidents happen and the consequences are not mitigated effectively, one of the indicated failures consists of ineffective emergency planning and response (EPR). EPR is an important aspect of the Process Safety Management (PSM) Standards, and the guidelines are stated in CFR 1910.119 (n) which explains the minimum elements of emergency response and procedures in handling emergency or small releases. Despite its implementation in 1992, CSB finds ineffective EPR system in certain accidents such as the Missouri DPS Enterprise Chlorine Gas Release accident in 2002. DPS EPR failed in planning on location of emergency equipment and accessibility. Many other accidents have occurred throughout the decade and even though organizations have their own EPR system, there are issues in meeting minimum PSM requirements. There also exists the problem of self-regulatory policies practiced by organizations, which might not meet these requirements as well. To help organizations meet these minimum requirements, the purpose of this paper is to present a structured and easy technique to plan and implement EPR as per PSM requirements. A model has been developed based on this technique, and its application has been tested as a case study in a refinery in Malaysia and discussed throughout this report. The results reflected the feasibility of this model as it helped users to track and manage documents efficiently. This technique has the potential to help users to manage EPR better and to reduce adverse impacts to people, environment and assets.     

移动式承压类特种设备应急平台研发

本文在搭建移动式承压类特种设备应急联动系统的背景下,重点开发移动式承压类特种设备应急平台.该平台是应急联动系统的核心控制部分,可实现危化品车辆管理、在线监测、事故分析、应急救援、统计分析、基础数据管理、系统管理等功能.应急联动系统融入“平战结合”理念,危险发生时,首先,平台从现场侦测装置自动采集数据;其次,启动事故分析和应急救援模块,必要时自动开启喷淋装置;第三,基于模型预测结果生成相应的应急救援方案;最后,发送到手持终端.该系统可以提升移动式承压类特种设备突发事件应急的及时性、科学性和有效性.