Time to burn: Flight delay,terminal efficiency,and fuel consumption in the National Airspace System

Improved Air Traffic Management (ATM) leading to reduced en route and gate delay, greater predictability in flight planning, and reduced terminal inefficiencies has a role to play in reducing aviation fuel consumption. Air navigation service providers are working to quantify this role to help prioritize and justify ATM modernization efforts. In the following study we analyze actual flight-level fuel consumption data reported by a major U.S. based airline to study the possible fuel savings from ATM improvements that allow flights to better adhere to their planned trajectories both en route and in the terminal area. To do so we isolate the contribution of airborne delay, departure delay, excess planned flight time, and terminal area inefficiencies on fuel consumption using econometric techniques. The model results indicate that, for two commonly operated aircraft types, the system-wide averages of flight fuel consumption attributed to ATM delay and terminal inefficiencies are 1.0–1.5% and 1.5–4.5%, respectively. We quantify the fuel impact of predicted delay to be 10–20% that of unanticipated delay, reinforcing the role of flight plan predictability in reducing fuel consumption. We rank terminal areas by quantifying a Terminal Inefficiency metric based on the variation in terminal area fuel consumed across flights. Our results help prioritize ATM modernization investments by quantifying the trade-offs in planned and unplanned delays and identifying terminal areas with high potential for improvement.     

运行车速检验在公路线形设计中的应用

文章分析了传统的路线线形设计特点及存在的问题,介绍运行车速协调性的理念在路线几何设计中的应用情况,同时按照运行车速的新理念对路线几何线形进行检验,以便在现有的设计条件下得到一个合理的线形设计方法。     

Solving the Median Shortest Path Problem in the Planning and Design of Urban Transportation Networks Using a Vector Labeling Algorithm

This paper proposes an alternative algorithm to solve the median shortest path problem (MSPP) in the planning and design of urban transportation networks. The proposed vector labeling algorithm is based on the labeling of each node in terms of a multiple and conflicting vector of objectives which deletes cyclic, infeasible and extreme-dominated paths in the criteria space imposing cyclic break (CB), path cost constraint (PCC) and access cost parameter (ACP) respectively. The output of the algorithm is a set of Pareto optimal paths (POP) with an objective vector from predetermined origin to destination nodes. Thus, this paper formulates an algorithm to identify a non-inferior solution set of POP based on a non-dominated set of objective vectors that leaves the ultimate decision to decision-makers. A numerical experiment is conducted using an artificial transportation network in order to validate and compare results. Sensitivity analysis has shown that the proposed algorithm is more efficient and advantageous over existing solutions in terms of computing execution time and memory space used.     

控制爆破在铁路特大桥基础施工中的应用

文章结合南宁至广州铁路北流河特大桥深水基础施工实例,对水下控制爆破施工时爆破参数的选择、钻孔布置形式、水下钻孔超深值的确定、装药及爆破技术等进行了介绍,并阐述了主要施工控制措施及爆破效果。     

重庆山区绕城高速公路立交规划与思考

文章以重庆绕城高速公路立交规划布局为研究基础,对城市外环高速公路立交的布局、等级、技术条件、类型和方案进行了较深入的探讨,并结合工程实践,提出了关于城市外环立交规划布局的几个关键问题的意见和建议。     

The Incorporation of Passenger Connectivity and Intermodal Considerations in Intercity Transport Planning

Congested road and air networks, coupled with the idea that transport systems should be balanced, have spawned the field of intercity intermodal passenger transport which is based on travel across connected networks that is as seamless as possible. There is a very large number of attributes that affect the objective and subjective quality of travel. Intercity public transport planning therefore requires an excellent understanding of connections between different services and how the quality of these connections affects passengers, operators and the society at large. This article reviews the vast literature over the last 20 years from Europe, North America and Asia that is related to intercity travel, the connectivity of transport and cooperation between different modes of transport and presents a simple yet powerful way to perceive connected transport systems. The article then reviews planning practice at a variety of states worldwide, and suggests a set of focus areas of research or gaps that once filled, the authors expect, will allow further development of connected intercity passenger travel.     

市域交通一体化规划研究实践——以沈阳市为例

为适应新型城镇化背景下市域范围内的交通出行需求,沈阳市域综合交通体系规划在分析市域交通出行特征和城镇体系结构的基础上,引入了自下而上的分层规划技术方法,建立了市域分级道路网系统、市域分级公交网系统、市域公交枢纽系统,并提出市域交通一体化的实施策略,将规划成果纳入城市建设项目库中。实践表明,自下而上的分层规划设计方法不仅能实现市域交通的一体化规划设计,更能保证市域交通规划成果的逐层实施。规划研究成果和方法将为沈阳市域其它基础设施规划和其它城市的同类规划提供有益借鉴。     

桩帽在PTC型控沉疏桩复合地基中的作用

文章通过PTC型预应力管桩桩帽疏桩复合地基现场静载试验,对试验测出的数据进行了比较分析,具体说明了桩帽在复合地基中的作用。     

农村公路路基路面压实度检测存在的问题及对策

文章围绕农村公路路基路面压实度检测存在的主要问题,分析问题产生的原因,并提出了相应的解决对策,为从事农村公路检测试验工作的工程技术人员提供借鉴。     

面向活力提升的城市郊区大学校园慢行交通改善规划设计——以同济大学嘉定校区为例

受城市中心区用地限制,近年来各大学因自身发展需要纷纷在城市郊区兴建校区。然而,现有城市郊区大学校园普遍存在空间尺度过大、人车冲突隐患严重、校园缺乏活力等问题。慢行是大学校园内最主要的出行方式,对慢行系统的改善规划设计成为提升校园活力的有效手段。通过分析厦门、上海、昆明和天津等城市的慢行交通系统规划,对比国内外高校的校园规划实例,研究校园慢行规划的特殊性。以同济大学嘉定校区为例,基于公共空间—公共生活调查方法对慢行交通现状进行调查分析,提出安全、便捷、舒适、活力的规划目标;将慢行交通设施与公共空间改造相结合,提出步行和自行车改善策略和方案,并对重点片区进行改善设计。