Commuters’ behavior towards upgraded bus services in Greater Beirut: Implications for greenhouse gas emissions,social welfare and transport policy

Climate change is one of the most critical environmental challenges faced in the world today. The transportation sector alone contributes to 22% of carbon emissions, of which 80% are contributed by road transportation. In this paper we investigate the potential private car greenhouse gas (GHG) emissions reduction and social welfare gains resulting from upgrading the bus service in the Greater Beirut Area. To this end, a stated preference (SP) survey on mode switching from private car to bus was conducted in this area and analyzed by means of a mixed logit model. We then used the model outputs to simulate aggregate switching behavior in the study area and the attendant welfare and environmental gains and private car GHG emissions reductions under various alternative scenarios of bus service upgrade. We recommend a bundle of realistic bus service improvements in the short term that will result in a reasonable shift to buses and measurable reduction in private car emissions. We argue that such improvements will need to be comprehensive in scope and include both improvements in bus level of service attributes (access/egress time, headway, in-vehicle travel time, and number of transfers) and the provision of amenities, including air-conditioning and Wi-Fi. Moreover, such a service needs to be cheaply priced to achieve reasonably high levels of switching behavior. With a comprehensively overhauled bus service, one would expect that bus ridership would increase for commuting purposes at first, and once the habit for it is formed, for travel purposes other than commuting, hence dramatically broadening the scope of private car GHG emissions reduction. This said, this study demonstrates the limits of focused sectorial policies in targeting and reducing private car GHG emissions, and highlights the need for combining behavioral interventions with other measures, most notably technological innovations, in order for the contribution of this sector to GHG emissions mitigation to be sizable.     

Why do some motorbike riders wear a helmet and others don’t? Evidence from Delhi,India

Road traffic accident fatalities lead to important private and social costs in the metropolitan areas of most low and middle income countries. An important share of these fatalities is due to injuries to the head and the neck. Helmets can provide efficient protection, but many drivers do not use them. We focus on helmet use behavior among motorbike users in Delhi. We use a detailed data set collected for the purpose of the study. To guide our empirical analysis, we rely on a model in which drivers decide on self-protection and self-insurance. The empirical findings suggest that risk-averse drivers are more likely to wear a helmet and that this has no systematic effect on speed. Helmet use also increases with education. Drivers who show a higher awareness of road risks seem to be both more likely to wear a helmet and to speed less. Controlling for risk awareness, we observe that drivers tend to compensate between speed and helmet use. The results can provide a basis for awareness-raising policies. They also show that improvements to the road infrastructure risk leading to risk-compensating behavior.     

Mining missing train logs from Smart Card data

This paper shows how to recover the arrival times of trains from the gate times of metro passengers from Smart Card data. Such technique is essential when a log, the set of records indicating the actual arrival and departure time of each bus or train at each station and also a critical component in reliability analysis of a transportation system, is missing partially or entirely. The procedure reconstructs each train as a sequence of the earliest exit times, called S-epochs, among its alighting passengers at each stations. The procedure first constructs a set of passengers, also known as reference passengers, whose routing choices are easily identifiable. The procedure then computes, from the exit times of the reference passengers, a set of tentative S-epochs based on a detection measure whose validity relies on an extreme-value characteristic of the platform-to-gate movement of alighting passengers. The tentative S-epochs are then finalized to be a true one, or rejected, based on their consistencies with bounds and/or interpolation from prescribed S-epochs of adjacent trains and stations. Tested on 12 daily sets of trains, with varying degrees of missing logs, from three entire metro lines, the method restored the arrival times of 95% of trains within the error of 24 s even when 100% of logs was missing. The mining procedure can also be applied to trains operating under special strategies such as short-turning and skip-stop. The recovered log seems precise enough for the current reliability analysis performed by the city of Seoul.     

基于单调关联系统的驾驶行为可靠度计算方法

为合理评估驾驶员驾驶行为的可靠性,提出了驾驶行为可靠度计算方法,将人机系统可靠性理论与驾驶行为链相结合,构建了基于感知、判断、操作元件及模块组的驾驶行为可靠性框图,确定了单项器官元件可靠度测试与计算方法,运用单调关联系统理论给出了功能模块可靠度及驾驶行为系统可靠度的量化模型,计算了模型中各生理、心理元件概率重要度,分析了其对驾驶行为的影响度。计算结果表明:事故组与非事故组间行为可靠性存在明显差异,非事故组的可靠性整体大于事故组,但整体可靠性呈下降趋势,事故组驾驶员整体操作稳定性较差;生理因素对驾驶行为可靠度影响度前期较大后期较小,而心理因素则相反。     

路基拓宽工程中桩承式加筋路堤处理的数值分析

为掌握拓宽路堤荷载作用下桩承式加筋路堤的工作特性及其处理效果,建立了三维有限元分析模型,采用土水耦合单元模拟地基土,三维薄膜单元模拟土工格栅,并基于接触单元考虑桩土界面的状态非线性,从土拱效应、土工格栅的拉膜效应以及桩土作用等方面验证了桩承式加筋路堤的工作机理。计算结果表明:土工格栅最大拉力发生在原坡脚位置的桩帽边缘处,外侧桩帽边缘的格栅应力逐渐减小;桩承式加筋路堤可使地表不均匀沉降由50.0 cm减小为8.3 cm,超孔隙水压力由63.7 kPa下降为11.0 kPa,并避免了老路基顶面出现的反坡现象,但在老路基处仍出现了较大的地基沉降和超孔隙水压力,故应充分重视老路边坡位置的地基处理。     

如何运用LEC进行航道工程施工危险源辨识

随着国家对内河航道建设力度的加大,航道工程施工的安全生产管理问题也愈显突出。根据航道工程施工的特点,依据国家和行业有关规定,提出了航道工程施工危险源辨识的依据和方法,为进一步加强航道工程施工单位自身安全管理的针对性、有效性,制定了适合政府监管的行业管理办法和适合施工企业管理的行业标准提供依据。     

交叉口行人过街心理及交通行为分析

行人与机动车的冲突是影响交叉口运行效率的重要因素。研究交叉口行人过街心理及行为的意义,分析行人过街过程及心理特征,总结行人过街等待时间、穿行速度特征、可接受间隙、违章行为及道路交通环境对行人心理和行为的影响,对行人的违章心理进行论述,并提出减少行人违章的措施。     

土木工程结构健康监测研究进展

阐述了实施土木工程结构健康监测的必要性,介绍了结构健康监测系统的内涵、组成、监控内容、监控系统功能及其工程应用,讨论了结构损伤检测中的两类方法,重点对损伤识别中的动力指纹法、模型修正法、神经网络法、遗传算法进行了分析和比较,阐述了健康监测领域今后的主要研究问题和发展方向.     

基于模态参数的结构损伤定位研究

基于振动学及有限元理论,推导出结构的频率平方的变化比为结构损伤位置的函数。以一光轴为例,先建立光轴裂纹数据库。然后再把测得的数据与数据库对比,相似性最高的为裂纹的位置所在,从而对损伤的位置进行了识别。最后,提出一些建议和有待解决的问题。     

Travel Behavior Analysis of the Females in Beijing

In urban life, compared with the same age group of male contrast, the statistical indicators of female travel behavior show significant differences. According to the sample data of Beijing 2005 travel survey, the paper analyzes the female travel behavior in the travel rate, travel consumption, trip purpose, and travel mode. Furthermore, the paper introduces the concept of the trip chain, to construct a female morning commuter trip chain choice behavior model with noncollection theories and methods, to analyze 10 factors that influence a female individual's choice of a trip chain from the source. Subsequently, model parameters are estimated, to calculate the incidents that can help to quantitatively understand the impact of each factor on a female's choice of the trip chain. The results show that the travel rate of elderly women is far lower than that of elderly men. Female travel proportion in shopping and social activities is obviously higher than that of male travelers, and factors related to the structure of families create important constraints in their average travel time consumption. The main travel mode of the female is walking, which is far more than that of a male. Age, whether they hold licenses, monthly income, and transport ownership are dominant factors for the female's choice of the trip chain.