TOD模式效益分析及评价指标体系

本文以TOD模式结构及功能分析为基础,通过确立模式开发涉及的效益主体及其期望目标,遵循效益最大化原则,将TOD模式系统效益划分为交通系统效益、经济效益、社会效益、环境效益4类进行评价分析.同时,在特性分析基础上,进一步确立了效益指标设置思路,并采用层次分析法建立了完整的TOD模式效益评价指标体系,为评价TOD模式效益并促进模式的进一步发展提供了理论支持.     

Fueling for contingencies: The hidden cost of unpredictability in the air transportation system

The aviation community is increasing its attention on the concept of predictability when conducting aviation service quality assessments. Reduced fuel consumption and the related cost is one of the various benefits that could be achieved through improved flight predictability. A lack of predictability may cause airline dispatchers to load more fuel onto aircraft before they depart; the flights would then in turn consume extra fuel just to carry excess fuel loaded. In this study, we employ a large dataset with flight-level fuel loading and consumption information from a major US airline. With these data, we estimate the relationship between the amount of loaded fuel and flight predictability performance using a statistical model. The impact of loaded fuel is translated into fuel consumption and, ultimately, fuel cost and environmental impact for US domestic operations. We find that a one-minute increase in the standard deviation of airborne time leads to a 0.88 min increase in loaded contingency fuel and 1.66 min in loaded contingency and alternate fuel. If there were no unpredictability in the aviation system, captured in our model by eliminating standard deviation in flight time, the reduction in the loaded fuel would between 6.12 and 11.28 min per flight. Given a range of fuel prices, this ultimately would translate into cost savings for US domestic airlines on the order of $120–$452 million per year.     

五路交叉口交通改善方法及其应用

五路交叉口通常用环岛来组织交通,随着交通量的迅猛增长,现在成了道路上的主要拥堵点,是交通界公认的比较棘手的问题,探讨五路交叉口的改善方案显得尤为必要。结合城市多路交叉口的常见问题,探讨了五路交叉口设计中的五路环形交叉、五路信号控制、五路环岛加信号控制、五路改四路等方法,分析了各方法的优缺点并提出其适用条件。以实际五路交叉口改造为例,对各个方案进行仿真,并对仿真结果进行对比分析,提出了五路环行交叉口的最优解决方案。     

The suitability of hedonic models for cost-benefit analysis: Evidence from commuting flows

We compare two estimates of benefits arising from the construction of new bridges in south-west Norway. One estimate comes from a hedonic property value model. Rather than follow an approach which is strictly theoretically correct, we adopt Rosen’s simple first-stage approach. To investigate and validate whether this simplified approach gives a reasonable estimate, we compare it to an estimate derived from a travel demand model. We find that a variant of an ex post hedonic house price model gives very similar estimates to the estimates from the travel demand model. This supports a hypothesis that the simplistic hedonic approach is reasonable.     

经济潜力模型法量化高速公路对沿线经济的带动效益

从空间经济学中的经济潜力模型出发,探讨了高速公路对沿线及周边地区经济的带动效益问题。通过提出区域可接近性概念,并利用区域经济潜力模型量化分析了高速公路对沿线区域经济的影响,并结合实际案例(京沪高速公路河北境内青县至吴桥段高速公路)测算出了高速公路对沿线区域经济增长的贡献。研究结果表明:至2020年,青吴高速公路对沿线经济的带动效益达13亿左右。     

Assessing the impact of tactical airport surface operations on airline schedule block time setting

With the growth of air traffic, airport surfaces are congested and air traffic operations are disrupted by the formation of bottlenecks on the surface. Hence, improving the efficiency and predictability of airport surface operations is not only a key goal of NASA’s initiatives in Integrated Arrival/Departure/Surface (IADS) operations, but also has been recognized as a critical aspect of the FAA NextGEN implementation plan. While a number of tactical initiatives have been shown to be effective in improving airport surface operations from a service provider’s perspective, their impacts on airlines’ scheduled block time (SBT) setting, which has been found to have direct impact on airlines’ on-time performance and operating cost, have received little attention. In this paper, we assess this impact using an econometric model of airline SBT combined with a before/after analysis of the implementation of surface congestion management (SCM) at John F. Kennedy International Airport (JFK) in 2010. Since airlines do not consider gate delay in setting SBT, we find that reduction in taxi-out time variability resulting from SCM leads to more predictable taxi-out times and thus decreases in SBT. The JFK SCM implementation is used as a case study to validate model prediction performance. The observed SBT decrease between 2009 and 2011 at JFK is 4.8 min and our model predicts a 4.2 min decrease. In addition, Charlotte Douglas International Airport (CLT) is used as an example to demonstrate how different surface operations improvements scenarios can be evaluated in terms of SBT reduction.     

公路科技成果直接经济效益分析方法探讨

本文以工厂热再生技术、半柔性基层两项科技成果直接经济效益计算为例,认真分析总结了公路科技成果直接经济效益计算原则及分析方法,将直接经济效益分类进行计算,为今后公路科技成果直接经济效益分析计算,提供有价值的参考。     

中国VTS的发展历程

本文回顾了中国ＶＴＳ的发展历程;对中国ＶＴＳ系统的类型、规模、功能、水平、机构和人员情况进行了全面评价;介绍了中国ＶＴＳ的作用和效益;阐述了今后的发展政策     

郑州至万州铁路河南段速度目标值选择

郑州至万州铁路是《铁路"十二五"发展规划》中快速铁路网中重要组成部分,也是河南省"米"字形快速铁路通道的重要组成部分,是我国西南地区通往中原、华北、东北地区便捷快速客运主通道和欧亚大陆桥中快速客运通道的重要组成部分,同时兼顾沿线城际及旅游客流运输。速度目标值是项目最重要的一项参数,而各方意见分歧很大,直接影响到项目的推进,为此结合本线功能定位,从路网布局、运量水平及特征、列车开行方案、运行时间、出行时间价值、工程投资、效益和能耗因素等8个方面,对速度250 km/h和350 km/h两个方案进行系统比较,建议采用350 km/h速度目标值方案,目前这一方案已经通过审查部门组织的各阶段审查,并已经进入实施建设当中。     

兰新二线强风地区防沙措施效益评价

基于现场观测试验,掌握试验段全年大风特征,并对不同类型的阻沙措施与固沙措施的防沙效果进行对比分析。结果表明:百里风区试验段的主导风向为NNW,烟墩风区试验段的主导风向主要为NE、ENE,分别占全年风向的21%和26%;百里风区阻沙措施性价比依次为:金属涂塑网措施斜插板式挡沙墙箱式挡沙墙插板式挡沙墙;烟墩风区阻沙措施性价比依次为:金属涂塑网措施高立式PE网措施斜插板式挡沙墙插板式挡沙墙;固沙措施性价比依次为:芦苇方格石方格沙方格;在现场试验研究的基础上,综合考虑工程造价和现场实际情况,建议试验段阻沙措施采用金属涂塑网沙障,固沙措施采用石方格沙障。