Road junction convex mirrors

Lateral visibility at road junctions can be improved by a convex mirror. Mainly in built-up areas, where visibility on one or both sides of an intersection may be hampered by space limitations, such a device is attractive because of its low cost and its actuated operating mode. However, little information is yet available concerning its efficiency and optimisation. The usefulness of a convex mirror from a safety viewpoint is experimentally assessed in a road junction where drivers who have to give way can observe lateral traffic through a convex mirror. Comparison is made between mirror users and non-users, in relation to their give way behaviour. The main finding is that the mirror appears as a device that enhances safety behaviour and can be recommended as a traffic aid.     

Preventing plant-pedestrian collisions: Camera & screen systems and visibility from the driving position

The issue of collisions between plant or site vehicles and pedestrians concerns numerous sectors of activity. Lack of visibility for drivers over their direct environments is one of the main causes of such accidents, which are often serious. Visibility can be improved indirectly by using camera-and-screen systems. This article gives the findings of a study on the detectability of a pedestrian by a driver using such a system in various configurations. It is thus recommended that, under the most unfavourable conditions, any pedestrian entering the danger zone be shown on the screen with at least a minimum height of 10 mm. Since the risk of non-detection is higher at the edges of the screen than at the centre, it is also recommended that the detection zone of the system cover an area extending beyond the danger zone under surveillance. Finally, since the size of the screen does not have a significant influence on detection, the choice of the screen size should be governed more by criteria regarding the fitting out of and the ergonomics of the cab or of the driving position.Relevance to industryPreventing mobile plant-pedestrian collisions is a problem area that concerns many enterprises, in particular in activity sectors like building and civil engineering, handling, transport/logistics and waste collection. Using camera-and-screen systems allows improving the visibility of the driver. This study gives recommendations about choice of such systems, in order to ensure better detection of pedestrians.     

基于行人安全的交通信号灯智能控制算法研究

提出了一种基于深度确定性策略梯度(DDPG, deep deterministic policy gradient)的行人安全智能交通信号控制算法;通过对交叉口数据的实时观测,综合考虑行人安全与车辆通行效率,智能地调控交通信号周期时长,相位顺序以及相位持续时间,实现交叉路口安全高效的智能控制;同时,采用优先经验回放提高采样效率,加速了算法收敛;由于行人安全与车辆通行效率存在相互矛盾,研究中通过精确地设计强化学习的奖励函数,折中考虑行人违规引起的与车辆的冲突量和车辆通行的速度,引导交通信号灯学习路口行人的行为,学习最佳的配时方案;仿真结果表明在动态环境下,该算法在行人与车辆冲突量,车辆的平均速度、等待时间和队列长度均优于现有的固定配时方案和其他的智能配时方案。     

Intersection fields for interactive global illumination

We present a novel visibility representation, Intersection Field (i-Field), to compute global illumination in interactive rates. The i-Field provides fast visibility and line-scene intersection queries. We factorize the direct illumination into local irradiance and visibility ratio. The latter is efficiently evaluated by querying the i-Field. The indirect illumination is simulated by photon tracing, which is also accelerated by the i-Field. By quickly detecting invalid portions, our approach can handle highly dynamic scenes, allowing light sources and scene geometries to be manipulated at interactive rates through rigid transformations and free deformations.     

Convex rear view mirrors compromise distance and time-to-contact judgements

Convex rear view mirrors increasingly replace planar mirrors in automobiles. While increasing the field of view, convex mirrors are also taken to increase distance estimates and thereby reduce safety margins. However, this study failed to replicate systematic distance estimation errors in a real world setting. Whereas distance estimates were accurate on average, convex mirrors lead to significantly more variance in distance and spacing estimations. A second experiment explored the effect of mirrors on time-to-contact estimations, which had not been previously researched. Potential effects of display size were separated from effects caused by distortion in convex mirrors. Time-to-contact estimations without a mirror were most accurate. However, not distortion, but visual angle seemed to cause estimation biases. Evaluating advantages and disadvantages of convex mirrors is far more complex than expected so far.     

Analysis of traffic hazard intensity: A spatial epidemiology case study of urban pedestrians

Traffic safety studies have underscored the hazardous conditions of pedestrians in the United States. This situation calls for increased public awareness of the pedestrian safety issue and better knowledge of the main factors contributing to traffic hazard for urban pedestrians. The purpose of this spatial epidemiology research is to gain greater insights into the geographic dimension exhibited by the intensity of traffic collisions involving urban pedestrians. Pedestrian crashes are studied in Buffalo, NY for years 2003 and 2004. Factors of hazard intensity are determined and compared for three age cohorts as well as for collisions occurring at intersections versus mid-block locations. Physical road characteristics and density of development, as well as socio-economic and demographic variables and potential trip attractors are examined. Spatial regression models are used to account for spatial dependencies. Econometric analysis underscores that all classes of environmental factors tested are significant drivers of pedestrian traffic hazard intensity. Results of the geographic analysis indicate that young and adult pedestrian traffic hazard intensities follow rather distinct logics. In addition, intersection and mid-block crashes differ by their socio-economic correlates, as well as their spatial distribution in the urban fabric.     

Using the Event Analysis of Systemic Teamwork (EAST) to explore conflicts between different road user groups when making right hand turns at urban intersections

Collisions between different types of road users at intersections form a substantial component of the road toll. This paper presents an analysis of driver, cyclist, motorcyclist and pedestrian behaviour at intersections that involved the application of an integrated suite of ergonomics methods, the Event Analysis of Systemic Teamwork (EAST) framework, to on-road study data. EAST was used to analyse behaviour at three intersections using data derived from an on-road study of driver, cyclist, motorcyclist and pedestrian behaviour. The analysis shows the differences in behaviour and cognition across the different road user groups and pinpoints instances where this may be creating conflicts between different road users. The role of intersection design in creating these differences in behaviour and resulting conflicts is discussed. It is concluded that currently intersections are not designed in a way that supports behaviour across the four forms of road user studied. Interventions designed to improve intersection safety are discussed.

Practitioner Summary: Intersection safety currently represents a key road safety issue worldwide. This paper presents a novel application of a framework of ergonomics methods for studying differences in road user behaviour at intersections. The findings support development of interventions that consider all road users as opposed to one group in isolation.     

Convex rear view mirrors compromise distance and time-to-contact judgements

Convex rear view mirrors increasingly replace planar mirrors in automobiles. While increasing the field of view, convex mirrors are also taken to increase distance estimates and thereby reduce safety margins. However, this study failed to replicate systematic distance estimation errors in a real world setting. Whereas distance estimates were accurate on average, convex mirrors lead to significantly more variance in distance and spacing estimations. A second experiment explored the effect of mirrors on time-to-contact estimations, which had not been previously researched. Potential effects of display size were separated from effects caused by distortion in convex mirrors. Time-to-contact estimations without a mirror were most accurate. However, not distortion, but visual angle seemed to cause estimation biases. Evaluating advantages and disadvantages of convex mirrors is far more complex than expected so far.     

The effects of a convex rear-view mirror on ocular accommodative responses

Convex mirrors are universally used as rear-view mirrors in automobiles. However, the ocular accommodative responses during the use of these mirrors have not yet been examined. This study investigated the effects of a convex mirror on the ocular accommodative systems. Seven young adults with normal visual functions were ordered to binocularly watch an object in a convex or plane mirror. The accommodative responses were measured with an infrared optometer. The average of the accommodation of all subjects while viewing the object in the convex mirror were significantly nearer than in the plane mirror, although all subjects perceived the position of the object in the convex mirror as being farther away. Moreover, the fluctuations of accommodation were significantly larger for the convex mirror. The convex mirror caused the 'false recognition of distance', which induced the large accommodative fluctuations and blurred vision. Manufactures should consider the ocular accommodative responses as a new indicator for increasing automotive safety.     

Facilitating energy savings with programmable thermostats: evaluation and guidelines for the thermostat user interface

Thermostats control heating and cooling in homes – representing a major part of domestic energy use – yet, poor ergonomics of these devices has thwarted efforts to reduce energy consumption. Theoretically, programmable thermostats can reduce energy by 5–15%, but in practice little to no savings compared to manual thermostats are found. Several studies have found that programmable thermostats are not installed properly, are generally misunderstood and have poor usability. After conducting a usability study of programmable thermostats, we reviewed several guidelines from ergonomics, general device usability, computer–human interfaces and building control sources. We analysed the characteristics of thermostats that enabled or hindered successfully completing tasks and in a timely manner. Subjects had higher success rates with thermostat displays with positive examples of guidelines, such as visibility of possible actions, consistency and standards, and feedback. We suggested other guidelines that seemed missing, such as navigation cues, clear hierarchy and simple decision paths.

Practitioner Summary: Our evaluation of a usability test of five residential programmable thermostats led to the development of a comprehensive set of specific guidelines for thermostat design including visibility of possible actions, consistency, standards, simple decision paths and clear hierarchy. Improving the usability of thermostats may facilitate energy savings.     

Expert evaluation of traffic signs: conventional vs. alternative designs

Traffic sign comprehension is significantly affected by their compliance with ergonomics design principles. Despite the UN Convention, designs vary among countries. The goal of this study was to establish theoretical and methodological bases for evaluating the design of conventional and alternative signs. Thirty-one conventional signs and 1–3 alternatives for each conventional sign were evaluated for their compliance with three ergonomics guidelines for sign design: physical and conceptual compatibility, familiarity and standardisation. Twenty-seven human factors and ergonomics experts from 10 countries evaluated the signs relative to their compliance with the guidelines. Analysis of variance across alternatives revealed that for 19 of the 31 signs, an alternative design received a significantly higher rating in its ergonomics design than the conventional sign with the same meaning. We also found a very high correlation between the experts’ ratings and comprehension from previous studies. In conclusion, many countries use signs for which better alternative designs exist, and therefore UN Convention signs should be re-examined, and ergonomics experts evaluation can serve as a good surrogate for road users’ comprehension surveys.

Practitioner summary: This study presents theoretical and methodological bases for evaluating the design of UN Conventional and alternative traffic signs. Human factors and ergonomics experts evaluated 31 conventional and 68 alternative road signs, based on ergonomics principles for sign design. Results indicated the need to re-examine poorly designed UN Convention signs.     

Developing national ergonomics standards for Thai industry

This paper reports activities initiated by the Thai Government and its Technical Committee on Ergonomics Standards (TC 887) to develop national ergonomics standards for Thai industry. The main objective is to promote ergonomics practice by disseminating recommended ergonomics principles and applications to various industries so that employers and/or management become aware of essential design concepts and work methods that help to improve workplace conditions and enhance workers’ safety. Initially, the paper discusses the history of ergonomics in Thailand and its progress during the past 30 years. Ergonomics research activities and industrial projects that have been conducted are also summarized. Government activities to develop national ergonomics standards are then described in detail. Steps already taken to achieve such goals include participating as a P-member of the ISO/TC 159, conducting national surveys on ergonomics education and ergonomics specialists, and drafting ergonomics standards.

Relevance to industry

It has been well recognized in developed countries that ergonomics principles help to increase workers’ productivity and enhance workplace safety. For industrially developing countries such as Thailand in which ergonomics is not well known, it is essential that national ergonomics standards be developed and disseminated to employers and/or management. Furthermore, national standards need to be compatible with international standards to allow Thai manufacturing companies to be competitive in international markets.     

Development of a volumetric projection technique for the digital evaluation of field of view

Current regulations for field of view requirements in road vehicles are defined by 2D areas projected on the ground plane. This paper discusses the development of a new software-based volumetric field of view projection tool and its implementation within an existing digital human modelling system. In addition, the exploitation of this new tool is highlighted through its use in a UK Department for Transport funded research project exploring the current concerns with driver vision. Focusing specifically on rearwards visibility in small and medium passenger vehicles, the volumetric approach is shown to provide a number of distinct advantages. The ability to explore multiple projections of both direct vision (through windows) and indirect vision (through mirrors) provides a greater understanding of the field of view environment afforded to the driver whilst still maintaining compatibility with the 2D projections of the regulatory standards.

Practitioner Summary: Field of view requirements for drivers of road vehicles are defined by simplified 2D areas projected onto the ground plane. However, driver vision is a complex 3D problem. This paper presents the development of a new software-based 3D volumetric projection technique and its implementation in the evaluation of driver vision in small- and medium-sized passenger vehicles.     

Back to the future: Brake reaction times for manual and automated vehicles

Rear-end collisions are often quoted as being a major cause of road traffic accidents. In response to this, a great deal of ergonomics research effort has been directed towards the analysis of brake reaction times. However, the engineering solution has been to develop advanced systems for longitudinal control, which, it is argued, will mitigate the problem of rear-end collisions. So far, though, there have been few empirical studies to determine how brake reaction times will be affected by such vehicle automation. This paper presents a literature review summarizing the current state of knowledge about driver responses in non-automated vehicles. The review covers driver factors, vehicle factors and situational factors. Following the review, some empirical data are presented from a driving simulator experiment assessing brake reaction times of skilled and unskilled drivers under two different levels of automation. When compared to previous data gathered during manual driving, there seems to be a striking increase in reaction times for these automated conditions. Implications for the design and safety of automated vehicle systems are discussed.     

Back to the future: brake reaction times for manual and automated vehicles

Rear-end collisions are often quoted as being a major cause of road traffic accidents. In response to this, a great deal of ergonomics research effort has been directed towards the analysis of brake reaction times. However, the engineering solution has been to develop advanced systems for longitudinal control, which, it is argued, will mitigate the problem of rear-end collisions. So far, though, there have been few empirical studies to determine how brake reaction times will be affected by such vehicle automation. This paper presents a literature review summarizing the current state of knowledge about driver responses in non-automated vehicles. The review covers driver factors, vehicle factors and situational factors. Following the review, some empirical data are presented from a driving simulator experiment assessing brake reaction times of skilled and unskilled drivers under two different levels of automation. When compared to previous data gathered during manual driving, there seems to be a striking increase in reaction times for these automated conditions. Implications for the design and safety of automated vehicle systems are discussed.     

The economic justification for ergonomics

The paper examines the impact of the economic climate on the emergence of industrial ergonomics and on its future development. A need is identified for a greater economic emphasis in the promotion of ergonomics. A case is developed using examples from the manufacturing, steel, coal and power industries to show that poor ergonomics can reduce the day-by-day efficiency of industry and that ergonomic change can result in direct economic benefit. Examples are given covering both the health/safety and performance/productivity aspects of ergonomics.     

基于物联网的高速公路主动发光诱导系统设计

近年来,交通压力与日俱增,高速公路的安全问题也日益凸显。研究表明,低能见度环境会导致交通安全事故发生机率提升。因此,提高高速公路低能见度环境下交通诱导水平从而提升交通运行的安全性愈加重要。为了解决上述问题,提出了一种基于物联网的高速公路路侧主动发光诱导系统。该系统基于智能检测技术和局域网构建技术,通过协同短距离Zigbee通信技术和长距离光纤通信技术,构建高速公路智能化监测控制网络,通过车-路协同控制路侧发光诱导装置对低能见度环境下的高速运行车辆进行有效诱导,提高高速公路的交通安全性。通过模拟实验,该系统能够大大降低设备铺设路段交通安全事故的发生率,且相比于原有LED发光设备,该系统也具有更好的节能效果。     

基于嵌入式计算机的激光雷达能见度仪的设计

针对不良能见度天气下的交通运输安全需求,设计了一台可用于水平及斜程能见度测量的激光雷达能见度仪.该仪器以嵌入式计算机PCM-3370E为控制和数据处理核心,实现对激光器、光子计数卡、门控电路工作时序的控制及能见度反演.在收发光学单元良好工作的基础上,通过易于操作的人机交互界面获得大气能见度的客观、便捷测量.     

LEARNING AND COORDINATION FOR AUTONOMOUS INTERSECTION CONTROL

Future urban road traffic management is an example of a socially relevant problem that can be modeled as a large-scale, open, distributed system, composed of many autonomous interacting agents, which need to be controlled in a decentralized manner. In this context, advanced, reservation-based, intersection control—where autonomous vehicles controlled entirely by agents interact with a coordination facility that controls an intersection, to avoid collisions and minimize delays—will be a possible scenario in the near future. In this article, we seize the opportunities for multiagent learning offered by such a scenario, studying i) how vehicles, when approaching a reservation-based intersection, can coordinate their actions in order to improve their crossing times, and therefore, speed up the traffic flow through the intersection, and ii) how a set of reservation-based intersections can cooperatively act over an entire network of intersections in order to minimize travel times.     

Image-based retro-reflectivity measurement of traffic signs in day time

The visibility of a traffic sign at night depends on its retro-reflectivity, a property that needs to be frequently monitored to ensure transportation safety. In the U.S., Federal Highway Administration (FHWA) maintains regulations to ensure minimum retro-reflectivity levels. Current measurement techniques either (a) use vehicle mounted device during the night, or (b) use manual handheld devices during the day. The former is expensive due to nighttime labor cost. The latter is time-consuming and unsafe. To address these limitations, this paper presents a computer vision-based technique to measure retro-reflectivity during daytime using a vehicle mounted device. The presented algorithms simulate nighttime visibility of traffic signs from images taken during daytime and measure their retro-reflectivity. The technique is faster, cheaper, and safer as it neither requires nighttime operation nor requires manual sign inspection. It also satisfies FHWA measurement guidelines both in terms of granularity and accuracy. The performance of the presented technique is evaluated under various testing conditions. The results are promising and demonstrate a strong potential in lowering inspection cost and improving safety in practical applications on retro-reflectivity measurement.