A GIS‐based method to identify cost‐effective routes for rural deviated fixed route transit

Deviated fixed route transit (DFRT) service connecting rural and urban areas is a growing transportation mode in the USA. Little research has been done to develop frameworks for route design. A methodology to explore the most cost‐effective DFRT route is presented in this paper. The inputs include potential DFRT demand distribution and a road network. A heuristic is used to build possible routes by starting at urban cores and extending in all network directions in certain length increments. All the DFRT routes falling in the length range desired by the users are selected. The cost effectiveness of those routes, defined by operating cost per passenger trip, is compared. The most cost‐effective route is selected and presented in a GIS map. A case study illustrates the methodology in several Tennessee metropolitan regions. The most cost‐effective route length is case specific; some routes (e.g. those out of our Nashville case) are most cost effective when short, while others (e.g. those out of Memphis) are most cost effective when long. Government agencies could use the method to identify routes with the lowest operating cost per passenger given a route length or an operating cost budget. Copyright © 2016 John Wiley & Sons, Ltd.     

Public–private partnerships: a review of economic considerations with particular reference to transportation projects

The paper sets in context some of the more recent work that has been conducted on public–private partnerships (PPPs) in the provision and operation of infrastructure. PPPs essentially involve a government or its agent signing an agreement with a private company or consortium to supply it with services with the private sector actor involved in major elements of designing, building, temporarily ‘owning’, and running the physical assets; basically they are long-term development and service contracts between government and a private partner. The paper outlines the development of economic thinking regarding the rationale behind PPPs, the extent to which unbundling is optimal and the forms that it may take, the nature of the contracts that are enacted and their renegotiation, the awarding of contracts, and matters of possible corruption. By way of focus, it also provides some indication of what empirical studies in the transportation have thrown up regarding the outcomes of PPPs.     

低压气液混输采气管道串接集气模式研究

针对杭锦旗气田高液气比气井井间串接集气距离长、管道压损大的问题,文中用权重法估算了影响管道气液混输距离的因素,表明管道直径是影响集气距离的最重要因素,权重比约56.1%。根据杭锦旗气田气井生产参数,对不同采气管道规格串接模式进行了研究,确定了适用于不同集气量和串接井数的采气管道规格系列,提出了直线式与辐射式相结合的井间串接模式,为杭锦旗气田地面集输站场和管网设计提供技术依据。     

Short‐term traffic flow prediction with linear conditional Gaussian Bayesian network

Traffic flow prediction is an essential part of intelligent transportation systems (ITS). Most of the previous traffic flow prediction work treated traffic flow as a time series process only, ignoring the spatial relationship from the upstream flows or the correlation with other traffic attributes like speed and density. In this paper, we utilize a linear conditional Gaussian (LCG) Bayesian network (BN) model to consider both spatial and temporal dimensions of traffic as well as speed information for short‐term traffic flow prediction. The LCG BN allows both continuous and discrete variables, which enables the consideration of categorical variables in traffic flow prediction. A microscopic traffic simulation dataset is used to test the performance of the proposed model compared to other popular approaches under different predicting time intervals. In addition, the authors investigate the importance of spatial data and speed data in flow prediction by comparing models with different levels of information. The results indicate that the prediction accuracy will increase significantly when both spatial data and speed data are included. Copyright © 2016 John Wiley & Sons, Ltd.     

The influence of bus service satisfaction on university students' mode choice

The purpose of this study was to determine the relationship between bus service satisfaction and the transport mode of choice among university students in Qatar. The degree of bus service satisfaction was collected directly from questionnaire surveys, in which university students were asked questions in relation to their satisfaction with the bus service they used and their transport mode of choice. These questions were categorized into three factors according to confirmatory factor analysis: service at bus stops, service of busses, and service of drivers. Furthermore, the students were asked which mode of transport they used given the choice between public and private transport. This study presents a structural equation model to determine how much bus service satisfaction affects people's decisions about their transport mode. The results from the analysis showed that three key factors—namely, service at bus stops, service of busses, and service of bus drivers—were strongly correlated to the mode of choice. In particular, the bus stop was strongly associated with ease of use, shade, cleanliness, safety, and crowdedness level, while the bus itself influenced reliability, travel time, and frequency. Complying with traffic laws and the driver's attitude were also important contributors to the level of bus service satisfaction. Ultimately, this study will be beneficial for policy/decision‐makers. It will allow them to determine what needs to be accomplished to encourage people to use public transportation. Copyright © 2016 John Wiley & Sons, Ltd.     

Understanding connectivity to international markets: a systematic review

Improving freight connectivity is increasingly a topic at the centre of the international trade and transport policy agendas. An examination of available documents and studies in both the policy-making and the academic fields shows that the concept of freight connectivity has often been defined in different ways, and thus has taken a variety of meanings. This poses the question on what connectivity is and what are its determinants in the context of international trade. We are not aware of any studies that have analysed, in a systematic way, the different perspectives and determinants of freight connectivity so as to increase access to international markets. This paper seeks to fill this gap by performing a systematic literature review that spans disciplines such as Transport Engineering, Transport and International Economics, and Supply Chain Management. The outcome of this examination is a multidisciplinary framework that hopefully will help stakeholders to understand freight connectivity to international markets better, as well as guide future research and analysis in policy-making.     

Short/medium-term prediction for the aviation emissions in the en route airspace considering the fluctuation in air traffic demand

This paper proposes a novel short/medium-term prediction method for aviation emissions distribution in en route airspace. An en route traffic demand model characterizing both the dynamics and the fluctuation of the actual traffic demand is developed, based on which the variation and the uncertainty of the short/medium-term traffic growth are predicted. Building on the demand forecast the Boeing Fuel Flow Method 2 is applied to estimate the fuel consumption and the resulting aviation emissions in the en route airspace. Based on the traffic demand prediction and the en route emissions estimation, an aviation emissions prediction model is built, which can be used to forecast the generation of en route emissions with uncertainty limits. The developed method is applied to a real data set from Hefei Area Control Center for the en route emission prediction in the next 5 years, with time granularities of both months and years. To validate the uncertainty limits associated with the emission prediction, this paper also presents the prediction results based on future traffic demand derived from the regression model widely adopted by FAA and Eurocontrol. The analysis of the case study shows that the proposed method can characterize well the dynamics and the fluctuation of the en route emissions, thereby providing satisfactory prediction results with appropriate uncertainty limits. The prediction results show a gradual growth at an average annual rate of 7.74%, and the monthly prediction results reveal distinct fluctuation patterns in the growth.     

基于能量法的气缸盖低周热机疲劳寿命预测方法研究

通过测试气缸盖本体解剖试样,获得气缸盖材料的循环应力应变特性,并利用仿真方法验证其合理性。在此基础上,依据发动机低周疲劳台架考核方法,运用子模型分析技术,得到考核循环内气缸盖火力面的应力分布和塑性变形特性。基于塑性应变能理论,结合试验测试,对火力面低周热机疲劳寿命进行预测和评估,分析表明排气鼻梁区的寿命较低,约为1100次。     

设计时速 160 km 以下铁路隧道（普货、有砟轨道）内轮廓标准研究

当前运营的时速160 km以下有砟轨道（普货）隧道内轮廓尽寸难以满足大型养护机械（特别是大型清筛机）作业空间需求,通过对新建时速160 km以下电气化铁路、单双线隧道内轮廓主要影响因素（建筑限界、接触网悬挂方式及布置、大型养护机械空间需求、轨道结构型式、侧沟及电缆槽设置等）进行综合分析,确定单双线有砟轨道隧道内轮廓控制性尺寸,并初步拟定满足大型养护机械作业要求的内轮廓方案,在此基础上通过对内轮廓方案的结构安全性、经济性及施工便利性进行综合比较,确定推荐方案,该成果对铁路行业隧道通用图编制有一定的参考价值。     

基于水动力—结构模型的VLGC强度和疲劳分析

超大型全冷式液化气船（VLGC）是国际上公认的设计及建造技术难度最大的船型之一,VLGC波浪载荷是船舶设计计算分析的重要载荷,准确的评估波浪载荷对船舶强度的设计非常重要。论文从DNV先进的水动力计算软件HydroD对VLGC船满载和压载工况下的波浪载荷进行了计算,得到了VLGC船相应工况下的运动响应和短期预报、长期预报值,并把计算出的波浪载荷传递到全船结构有限元结构模型中,加载分析得到了VLGC船的应力分布,对相应地方做了适当改进和加强,并对典型节点进行疲劳强度分析,得到了典型节点的疲劳寿命。对VLGC船整个波浪载荷传递到有限元模型的这一套流程做了分析和研究,也为进一步应用水动力方法计算其它船型的结构强度和疲劳寿命打下了良好的基础。