Analyzing road safety in the United States

This paper reviews road safety performance in the United States. The paper develops a framework for assessing dimensions of road safety, and analyzes the importance of economic factors, travel patterns, demographics, road/traffic/vehicle technology, driver behavior, and public policy. Issues and challenges for future road safety research are discussed.     

Why are maritime ports (still) urban,and why should policy-makers care?

Despite ongoing transformations in the maritime transportation industry and the rise of global supply chain systems, most of the world's important container ports remain urban. Ports continue to occupy urban spaces, are embedded in localized knowledge systems, draw on urban labour markets and infrastructure and are subject to local politics and policy concerns. We identify contemporary geographic theories which help us understand the often increasingly urban attachment of core economic activities despite globalization. We explore how these theories may apply to port studies, highlighting both how they have been used by maritime scholars to this point and also why further development and application are warranted. We argue that a central concern of these geographic theories is the articulation of place- and sector-specific processes operating at a variety of spatial scales. This is in contrast to most maritime studies which continue to be dominated by perspectives which emphasize the global logic of the transportation industry and the analysis of space in generalized and abstract terms. We conclude that a re-appreciation in maritime studies of urban economic processes, informed by geographical theory, will provide policy-makers and others with more understanding of why deep connections between ports and urban places still matter.     

Factors contributing to bicycle–motorised vehicle collisions: a systematic literature review

Bicycle–motorised vehicle (BMV) collisions account for the majority of the recorded bicyclists’ fatalities and serious injuries. This systematic review intends to examine the main factors contributing to BMV collisions. We performed a comprehensive literature review on Scopus, TRID, ProQuest, and Web of Science databases. Fifty-nine English-language peer-reviewed articles met the eligibility criteria and were included in the final analysis. The main factors contributing to BMV collisions identified were classified in accordance with a recently published conceptual framework for road safety. The majority of studies have identified factors related to road users’ behaviour (59.3%) and infrastructure characteristics (57.6%). A minority of studies identified variables related to exposure (40.7%) and vehicles (15.3%) as contributor factors to BMV collisions. A small but significant proportion of studies (20.3%) provided evidence that environmental factors may also play a role, although to a lesser extent, in determining BMV collisions. In addition to the three factors comprised in the applied conceptual framework for road safety, we identified environmental conditions as a category of factors contributing to BMV collisions.     

Independently Rotating Wheel Systems for Railway Vehicles-A State of the Art Review

This paper surveys the state-of-the-art in the field of Independently Rotating Wheel systems (IRW) for railway vehicles. Various methods that have been adopted to provide guidance capability to the system are discussed. Results of the stability and response characteristics of such systems obtained through both experimental and analytical efforts by various researchers are reviewed. Some critical research needs are identified.     

Ship assignment with hub and spoke constraints

As the shipping industry enters the future, an increasing number of technological developments are being introduced into this market. This has led to a significant change in business operations, such as the innovative design of hub and spoke systems, resulting in cargo consolidation and a better use of the ship's capacity. In the light of this new scenario, the authors present a successful application of integer linear programming to support the decision-making process of assigning ships to previously defined voyages - the rosters. The tool used to build the final models was the MS-Excel Solver (Microsoft® Excel 97 SR-2, 1997), a package that enabled the real case studies addressed to be solved. The results of the experiment prompted the authors to favour the assignment of very small fleets, as opposed to the existing high number of ships employed in such real trades,     

The relationship between transportation perceptions and behavior over time

The aim of this paper is to discuss cross-lagged panel analysis in terms of the causal inferences it generates about the relationship of beliefs about modes and mode choice behavior. Frequencies of use of the single-occupant automobile (SOA), bus and carpool, as well as beliefs about each of the modes, were collected from a sample of central business district commuters at two points in time. The belief variables for each mode were summed to form composite measures and were corrected for unreliability due to measurement error.Perceptions of each mode and the frequency of its use were analyzed for influences operating over time. A time interval was assumed to exist during which the variables causally operated on each other. It was assumed that the time necessary for an individual to change modes based on his perception was equivalent to the interval required for a person to alter perceptions based on his experience. The causal structure relating the two variables was also assumed to be stable over time. An additional assumption was required to distinguish between third variable effects, or spuriousness, and dual causation: if a third variable were to be causing the relationship, it would be operating at a relatively constant rate over time.A strong causal relationship was found to be operating between beliefs about SOA and bus and use of those modes over time. The relationship is mutually causative; beliefs determine behavior and behavior reinforces and changes perceptions. Analysis of the carpool data indicated that the causal structure had changed over time and could not be analyzed with this technique. In general, support is evidenced for an adaptation or learning process interpretation of the relationship between beliefs and mode choice behavior.     

Numerical experiments on the prediction of sea surface temperature anomalies in the Gulf of Mexico

The conservation of thermal energy equation applied to the mixed layer of the ocean, has been used to predict the sea surface temperature anomalies (SSTA) and the month-to-month changes in the Gulf of Mexico. The model includes the horizontal transport of heat by mean ocean currents and by turbulent eddies, as well as the heating by short and long wave radiation, evaporation and sensible heat given off to the atmosphere. A comparative study is carried out on the relative importance of the heating and transport terms. An objective verification of the skill of the predictions is presented for each season and for the whole period from March 1986 to February 1987. The predictions using only the heating terms have some skill over the control predictions (persistence and return to normal). The skill is substantially increased when the horizontal transport of heat by turbulent mixing is included in the model. The incorporation in the model of the Ekman wind drift current anomalies computed from the anomalous surface geostrophic wind improves appreciably the skill of the predictions in winter and fall.The mixed layer depth computed using the Kraus and Turner theory with dissipation, shows that the depths in summer and fall are shallower than in spring and winter. The effect of the shallow mixed layer depth in the model becomes apparent in summer and fall, improving the skill of the predictions in these seasons, with respect to the skill obtained using a constant mixed layer depth of 60 m.The incorporation in the model of the cooling in the mixed layer by turbulent entrainment of colder water from the thermocline, does not improve in an appreciable way the average skill of the predictions.     

双向与单向道路网络:哪一个更高效?

为了改善机动车的可达性并避免驾驶人迷失,城市政府和规划师开始将中心城区传统的单向道路网络转换成双向行驶。双向道路网络可提升经济活力水平和中心城区的宜居性,而单向道路网络可提高通行能力。指出使用出行服务能力指标来衡量道路网络效率更适宜,将单向行驶与双向行驶道路网络的出行服务能力进行对比,后者交叉口的处理包括左转专用车道、左转渠化和禁止左转三种方式。结果显示,与传统认知和设计手册相反,双向道路网络通常比单向道路网络更有效率。在出行距离较短的情况下,允许转向的双向道路网络比单向道路网络的出行服务能力更高;禁止左转的双向道路网络比单向道路网络造成的绕行更少。     

2D非稳态方柱绕流的数值模拟与分析

用有限体积法对与来流夹角为45°以及夹角为0°的方柱绕流进行了数值模拟分析.从对方柱的绕流的数值模拟结果可以得出倾角为45°的方柱对尾涡的影响较之倾角为0°的方柱要大得多.由此可知,特征长度越大对柱体尾部涡影响越大.同时还对方柱的受力进行了计算和分析,并与现有实验数据、文献资料进行了比较,两者互相吻合.