Identifying factors affecting the safety of mid-block bicycle lanes considering mixed 2-wheeled traffic flow

Objective: Electric bikes (e-bikes) have been one of the fastest growing trip modes in Southeast Asia over the past 2 decades. The increasing popularity of e-bikes raised some safety concerns regarding urban transport systems. The primary objective of this study was to identify whether and how the generalized linear regression model (GLM) could be used to relate cyclists' safety with various contributing factors when riding in a mid-block bike lane. The types of 2-wheeled vehicles in the study included bicycle-style electric bicycles (BSEBs), scooter-style electric bicycles (SSEBs), and regular bicycles (RBs).

Methods: Traffic conflict technology was applied as a surrogate measure to evaluate the safety of 2-wheeled vehicles. The safety performance model was developed by adopting a generalized linear regression model for relating the frequency of rear-end conflicts between e-bikes and regular bikes to the operating speeds of BSEBs, SSEBs, and RBs in mid-block bike lanes.

Results: The frequency of rear-end conflicts between e-bikes and bikes increased with an increase in the operating speeds of e-bikes and the volume of e-bikes and bikes and decreased with an increase in the width of bike lanes. The large speed difference between e-bikes and bikes increased the frequency of rear-end conflicts between e-bikes and bikes in mid-block bike lanes. A 1% increase in the average operating speed of e-bikes would increase the expected number of rear-end conflicts between e-bikes and bikes by 1.48%. A 1% increase in the speed difference between e-bikes and bikes would increase the expected number of rear-end conflicts between e-bikes/bikes by 0.16%.

Conclusions: The conflict frequency in mid-block bike lanes can be modeled using generalized linear regression models. The factors that significantly affected the frequency of rear-end conflicts included the operating speeds of e-bikes, the speed difference between e-bikes and regular bikes, the volume of e-bikes, the volume of bikes, and the width of bike lanes. The safety performance model can help better understand the causes of crash occurrences in mid-block bike lanes.     

Public perception of locally unwanted facilities in Hong Kong: implications for conflict resolution

This paper aims to investigate factors affecting public attitude towards the siting of locally unwanted land uses (LULUs) and to explore the possible strategies to resolve such conflicts. Three questionnaire surveys were undertaken in communities with different siting experiences and socio-economic profiles. Over 750 individuals were successfully interviewed in each study district. The three communities were found to share similar risk beliefs but show variations in the level of awareness of and response to LULUs. In communities with a disproportionate share of LULUs, many residents did not trust the government in handling LULU issues and thought that the siting process was unfair. The results of the binary logistic regression analysis show that people are likely to oppose the siting of a LULU in their community if they have a negative siting experience, do not perceive the need, accord a high risk to the facility and have a low level of trust in government. The resolution strategies preferred by the public are greater public participation and effective mitigation of risks and impacts, rather than provision of compensation and incentives. All these call for policy-makers to be sensitive to local concerns, engage the public in the process, communicate risks effectively and foster trust building.     

围湖造田不同土地利用方式土壤有机碳和易氧化碳

围湖造田是我国20世纪50年代后期开始大量出现的与水争地的人类干扰活动。以太湖流域肖甸湖区为试验地,测定分析了该围湖造田区香樟（Cinnamomum camphora）林、水杉（Metasequoia glyptostroboides）林、毛竹（Phyllostachys heterocycla）林和农田4种不同典型土地利用方式35年后0～10 cm、10～20 cm、20～40 cm土壤有机碳和易氧化碳含量的差异,以及土壤易氧化碳的季节动态。结果表明：表层（0～10 cm）土壤有机碳含量林地显著高于农田,阔叶林高于针叶林。土壤易氧化碳含量随季节与土层深度的变化而变化,香樟林与毛竹林春夏季节大于冬季,水杉林与农田季节波动较平缓。4种土地利用方式下土壤有机碳和易氧化碳均随土层增加含量递减。与围湖地区内的溪流底泥相比,林地与农田表层土壤有机碳含量均有明显增加;与旱地发育的植被土壤相比,围湖后的土壤有机碳含量较低,易氧化碳含量较高,土壤有机碳稳定性较差。围湖造田作为人类对自然生态系统的一种干扰方式,显著改变了原有生态系统的碳循环特征,因此在研究全球碳循环中,围湖造田对生态系统碳循环的影响应该给予充分考虑。     

Competing land uses and fossil fuel,and optimal energy conversion rates during the transition toward a green economy under a pollution stock constraint

We study the transition to a carbon-free economy in a model with a polluting non-renewable resource and a clean renewable resource. Transforming primary energy into ready-to-use energy services is costly and more efficient energy transformation rates are more costly to achieve. Renewable energy competes with food production for land and the food productivity of land can be improved at some cost. To avoid catastrophic climate damages, the pollution stock is mandated to stay below a given cap. When the economy is not constrained by the cap, the efficiency of energy transformation increases steadily until the transition toward the ultimate green economy; when renewable energy is exploited, its land use rises at the expense of food production; food productivity increases together with the land rent but food production drops; the food and energy prices increase and renewables substitute for non-renewable energy. During the constrained phase, the economy follows a constant path of prices, quantities, efficiency rates, food productivity and land rent, a phenomenon we call the ‘ceiling efficiency paradox’.     

加速车道几何参数对合流区交通状况的影响分析*

为分析加速车道几何参数对合流区交通状况的影响,基于实验方案和效率-冲突率评价指标,构建实验平台并标定对应参数,结合实际交通场景数据及速度偏差和交通冲突相关系数指标,验证实验平台有效性。结果表明:w,l随主线流量增大而增大,合流区交通状况逐步变好;随主线流量增大,在l=60 m时,w对合流区交通状况的影响较大且整体交通状况较差,而l相应增大后,w对交通状况影响较小。     

Observed activation status of lane departure warning and forward collision warning of Honda vehicles at dealership service centers

Objective: There are little objective data on whether drivers with lane departure warning and forward collision warning systems actually use them, but self-report data indicate that lane departure warning may be used less and viewed less favorably than forward collision warning. The current study assessed whether the systems were turned on when drivers brought their vehicles to dealership service stations and whether the observational protocol is a feasible method for collecting similar data on various manufacturers' systems.

Methods: Observations of 2013–2015 Honda Accords, 2014–2015 Odysseys, and 2015 CR-Vs occurred at 2 U.S. Honda dealerships for approximately 4 weeks during Summer 2015.

Results: Of the 265 vehicles observed to have the 2 systems, 87 (32.8%) had lane departure warning turned on. Accords were associated with a 66% increase in the likelihood that lane departure warning was turned on compared with Odysseys, but the rate was still only about 40% in Accords. In contrast, forward collision warning was turned on in all but one of the observed vehicles.

Conclusions: Observations found that the activation rate was much higher for forward collision warning than lane departure warning. The observation method worked well and appears feasible for extending to other manufacturers.     

Injury-severity analysis of lane change crashes involving commercial motor vehicles on interstate highways

Introduction: One of the challenging tasks for drivers is the ability to change lanes around large commercial motor vehicles. Lane changing is often characterized by speed, and crashes that occur due to unsafe lane changes can have serious consequences. Considering the economic importance of commercial trucks, ensuring the safety, security, and resilience of freight transportation is of paramount concern to the United States Department of Transportation and other stakeholders. Method: In this study, a mixed (random parameters) logit model was developed to better understand the relationship between crash factors and associated injury severities of commercial vehicle crashes involving lane change on interstate highways. The study was based on 2009–2016 crash data from Alabama. Results: Preliminary data analysis showed that about 4% of the observed crashes were major injury crashes and drivers of commercial motor vehicles were at-fault in more than half of the crashes. Acknowledging potential crash data limitations, the model estimation results reveal that there is increased probability of major injury when lane change crashes occurred on dark unlit portions of interstates and involve older drivers, at-fault commercial vehicle drivers, and female drivers. The results further show that lane change crashes that occurred on interstates with higher number of travel lanes were less likely to have major injury outcomes. Practical Applications: These findings can help policy makers and state transportation agencies increase awareness on the hazards of changing lanes in the immediate vicinity and driving in the blind spots of large commercial motor vehicles. Additionally, law enforcement efforts may be intensified during times and locations of increased unsafe lane changing activities. These findings may also be useful in commercial vehicle driver training and driver licensing programs.     

基于ISO 26262的车道偏离预警系统概念设计与仿真

以道路车辆功能安全规范标准ISO 26262为准则,对汽车的车道偏离预警系统（LDWS）进行了概念设计。首先分析了ISO 26262功能安全规范概念阶段的活动内容,并在此基础上,完成车道偏离预警系统的项目定义、危险分析和评估,设计了功能安全概念的相关工作,确定了功能安全等级和安全目标。最后搭建了UML仿真模型对LDWS概念设计阶段进行仿真测试,测试结果表明此设计能够满足ISO 26262规范标准,实现了车道偏离预警系统的功能安全概念设计,对车道偏离预警系统的安全开发具有指导意义。     

中国核损害责任制度的缺陷及立法设想

随着核能和平利用的发展。核能的安全性日益引起人们的关注，核损害及其赔偿已经成为无法回避的问题。我国现行核损害责任制度存在重大缺陷．应该尽快建立和完善我国大陆的核损害责任制度。建议：①在民事基本法的层次上，对核损害责任做出全面而具体的规定。②制定核领域的基本法《原子能法》或《核设施法》。③制定《核损害赔偿法》或《核损害责任法》或《核损害赔偿条例》。最后提出我国大陆核损害责任立法的主要内容。     

基于Multi-class SVM的车辆换道行为识别模型研究

自动安全换道是车辆实现无人驾驶的关键,为精确识别行驶车辆换道状态,保证行车安全,设计了一种基于多分类支持向量机(Multi-class Support Vector Machine,Multiclass SVM)的车辆换道识别模型。从NGSIM数据集中选取美国101公路车辆轨迹数据进行分类处理,并将车辆换道过程划分为车辆跟驰阶段、车辆换道准备阶段和车辆换道执行阶段。采用网格搜索结合粒子群优化算法(Grid Search-PSO)对SVM模型中惩罚参数C和核参数g进行寻优标定,利用多分类支持向量机换道识别模型对样本数据进行训练和测试,模型测试精度达97.68%。研究表明,模型能够很好地识别车辆在换道过程中的行为状态,为车辆换道阶段的研究提供支持。