叉车“安全保护与防护装置”定检项目的探讨

本文通过综合比较现行安全技术规范、标准对叉车“安全保护与防护装置”的要求,分析叉车“安全保护与防护装置”的检验范围及内容,对其中争议较大项目的检验要求和方法提出建议.     

对电梯应急演练可能出现的三个误区的讨论

文章总结电梯应急演练中存在的问题,对照有关法规,分析存在的误区,提出正确做法,指导和促进科学的电梯安全管理,培养良好的安全文化,为科研生产提供安全保障.     

加强铁路集中空调通风系统管理的探讨

为避免集中空调通风系统传播、扩散空气传播性疾病的安全隐患,在概述集中空调通风系统在某铁路局集团公司客运站应用的基础上,从首选自然通风、确保供风安全、加强通风系统清洗消毒等方面说明加强铁路客运站通风系统管理的措施,提出明确责任分工、健全卫生管理制度、开展卫生学评价、做好监督检查和应急处理等保障措施,从而有效阻断传播途径,保障广大旅客和铁路工作人员身体健康。     

建筑施工现场存在的安全和环保问题及其对策

随着我国社会经济发展进程的不断推进,建筑行业发展趋势也有了空前的提高。基于这样的发展态势,建筑行业市场中竞争越来越激烈。建筑工程在施工现场的安全和环境保护问题与企业的经济效益、人们的健康、生命安全有着很大的关系。建筑工程施工现场安全和环境管理措施的有效程度,决定着企业的管理水平,也能在很大程度上影响企业的发展。     

Are parents ready to use autonomous vehicles to transport children? Concerns and safety features

Introduction: This study addressed a gap in the literature – the potential of using autonomous vehicles (AV) to enhance children’s mobility. Prior studies documented the perceived benefits and concerns about this prospect, but did not examine the features in AV and support mechanisms that are desired by potential users. Method: An on-line survey was used to collect public opinions within the United States. In the survey, willingness to use AVs for this use case was asked twice to assess if participants changed their mind after being asked about concerns related to this prospect and importance of car features. A combination of statistical and machine-learning methods were used to profile individuals with high versus low post-willingness and to identify variables that differentiated the two groups. Results: Results indicated that respondents who were lower on their post-willingness to use AVs to transport children were more concerned about how AVs would protect children, how someone could harm the children inside, and whether there would be someone at the destination. In addition, they were less in favor of technology, older in age, and rated car features such as having a designated adult waiting at destination, a camera, and a microphone as relatively required (as opposed to optional). These results highlight potential users’ needs and requirements as they think about AVs in the context of parent–children mobility practices. Practical Applications: Relevant stakeholders should develop deployment and implementation plans while taking into account ridership contexts and vulnerable road users who can benefit from enhanced mobility.     

Stability and safety evaluation of mixed traffic flow with connected automated vehicles on expressways

Introduction: Connected automated vehicles (CAVs) technology has deeply integrated advanced technologies in various fields, providing an effective way to improve traffic safety. However, it would take time for vehicles on the road to vehicles from human-driven vehicles (HDVs) progress to CAVs. Moreover, the Cooperative Adaptive Cruise Control (CACC) vehicle would degrade into the Adaptive Cruise Control (ACC) vehicle due to communication failure. Method: First, the different car-following models are used to capture characteristics of different types of vehicles (e.g., HDVs, CACC, and ACC). Second, the stability of mixed traffic flow is analyzed under different penetration rates of CAVs. Then, multiple safety measures, such as standard deviation of vehicle speed (SD), time exposed rear-end crash risk (TER), time exposed time-to-collision (TET), and time-integrated time-to-collision (TIT) are used to evaluate the safety of mixed traffic flow on expressways. Finally, the sensitivity of traffic demand, the threshold of time-to-collision (TTC), and the parameters of car-following models are analyzed based on a numerical simulation. Results: The results show that the ACC vehicle has no significant impact on the SD of mixed traffic flows, but it leads to the deterioration of TET and TIT, making the reduction proportion of TER slower. When the penetration rate exceeds 50%, the increase of CACC vehicles reduces traffic safety risks significantly. Furthermore, the increase in traffic demand and car-following parameters worsens traffic safety on expressways. Conclusions: This paper suggests that the CACC vehicles degenerate into ACC vehicles due to communication failure, and the safety risk of mixed traffic flow increases significantly. Practical Applications: The application of CAVs can improve the stability and safety of traffic flow.     

Urban road space allocation incorporating the safety and construction cost impacts of lane and footpath widths

Introduction: Walkability continues to attract great attention from urban planners, designers, and engineers as they recognize not only the merits of pedestrian facilities in terms of the health benefits but also their demerits in terms of accident risk to pedestrians. Wide footpaths improve the pedestrian environment and experience, and thereby motivate travelers to walk as much as possible. However, if footpaths are too wide, they may leave a smaller space for the roadway. On the other hand, wide road lanes may lead to higher road vehicle safety but are costly to construct and maintain and also may leave little space for the footpath. Evidently, for a fixed urban space, what is needed is an optimal balance between the vehicle lane and pedestrian path. This problem is encountered routinely in dense cities including Hong Kong where land availability is severely limited. Method: To address the issue, this paper first establishes safety performance functions (SPFs) for the pedestrian space and the road space, using the random-parameter negative binomial regression. The results indicate the extent to which road lane and footpath width changes are associated with changes in in-vehicle occupant and pedestrian casualties. Then the paper uses the SPFs to develop a methodology for optimizing the width allocations to the road lanes and footpaths, duly considering the user (safety) costs and agency (construction) costs associated with each candidate allocation of the widths. Finally, the paper analyzes the sensitivity of the optimal solution to the relative weights of user cost and agency cost. Results: When user and agency costs are considered equally important, the optimal lane width is 5.4 m. Conclusion: It is observed that the road space allocation ratio used by the Hong Kong road agency suggests that the agency places a higher weight to user cost compared to agency cost. Practical Application: The findings can help incorporate design-safety relationships, and the stakeholders (agency and users) perspectives in urban road and footpath design.     

A conceptual framework to understand the role of built environment on traffic safety

IntroductionMany U.S. cities have adopted the Vision Zero strategy with the specific goal of eliminating traffic-related deaths and injuries. To achieve this ambitious goal, safety professionals have increasingly called for the development of a safe systems approach to traffic safety. This approach calls for examining the macrolevel risk factors that may lead road users to engage in errors that result in crashes. This study explores the relationship between built environment variables and crash frequency, paying specific attention to the environmental mediating factors, such as traffic exposure, traffic conflicts, and network-level speed characteristics. Methods: Three years (2011–2013) of crash data from Mecklenburg County, North Carolina, were used to model crash frequency on surface streets as a function of built environment variables at the census block group level. Separate models were developed for total and KAB crashes (i.e., crashes resulting in fatalities (K), incapacitating injuries (A), or non-incapacitating injuries (B)) using the conditional autoregressive modeling approach to account for unobserved heterogeneity and spatial autocorrelation present in data. Results: Built environment variables that are found to have positive associations with both total and KAB crash frequencies include population, vehicle miles traveled, big box stores, intersections, and bus stops. On the other hand, the number of total and KAB crashes tend to be lower in census block groups with a higher proportion of two-lane roads and a higher proportion of roads with posted speed limits of 35 mph or less. Conclusions: This study demonstrates the plausible mechanism of how the built environment influences traffic safety. The variables found to be significant are all policy-relevant variables that can be manipulated to improve traffic safety. Practical Applications: The study findings will shape transportation planning and policy level decisions in designing the built environment for safer travels.     

Secondary collisions and injury severity: A joint analysis using structural equation models

Objective: This study aims to investigate the contributing factors to secondary collisions and the effects of secondary collisions on injury severity levels. Manhattan, which is the most densely populated urban area of New York City, is used as a case study. In Manhattan, about 7.5% of crash events become involved with secondary collisions and as high as 9.3% of those secondary collisions lead to incapacitating and fatal injuries.

Methods: Structural equation models (SEMs) are proposed to jointly model the presence of secondary collisions and injury severity levels and adjust for the endogeneity effects. The structural relationship among secondary collisions, injury severity, and contributing factors such as speeding, alcohol, fatigue, brake defects, limited view, and rain are fully explored using SEMs. In addition, to assess the temporal effects, we use time as a moderator in the proposed SEM framework.

Results: Due to its better performance compared with other models, the SEM with no constraint is used to investigate the contributing factors to secondary collisions. Thirteen explanatory variables are found to contribute to the presence of secondary collisions, including alcohol, drugs, inattention, inexperience, sleep, control disregarded, speeding, fatigue, defective brakes, pedestrian involved, defective pavement, limited view, and rain. Regarding the temporal effects, results indicate that it is more likely to sustain secondary collisions and severe injuries at night.

Conclusions: This study fully investigates the contributing factors to secondary collisions and estimates the safety effects of secondary collisions after adjusting for the endogeneity effects and shows the advantage of using SEMs in exploring the structural relationship between risk factors and safety indicators. Understanding the causes and impacts of secondary collisions can help transportation agencies and automobile manufacturers develop effective injury prevention countermeasures.     

Managing stormwater for urban sustainability: an evaluation of local comprehensive plans in the Chesapeake Bay watershed region

This study uses a developed plan coding protocol in evaluating the quality of 76 comprehensive plans to examine whether local comprehensive plans have adequately integrated the concepts of sustainable stormwater management. The Chesapeake Bay watershed was chosen for the investigation because degraded stormwater runoff from nearby urban and suburban jurisdictions have critically polluted the watershed. The findings indicate that the majority of local governments have not sufficiently incorporated the sustainable stormwater management principles into their comprehensive plans. Five plan components (factual basis, goals and objectives, inter-organizational cooperation, policies, tools and strategies, and implementation) appear weak in realizing the concepts. The current study concludes by providing policy implications and recommendations to increase awareness and understanding of sustainable stormwater management concepts and to produce better implementation plans that integrate stormwater, ecosystem, and environmental planning comprehensively.