Induced traffic and economic appraisal

Economic appraisal of major roads in the UK is based on a set of standard procedures and conventions. A central assumption has been that the volume and pattern of traffic in any given year is independent of the quality of service offered by the network — the fixed trip matrix assumption. Failing to consider induced traffic can have serious consequences for the accuracy and robustness of the measured traffic benefits from road improvements. Assessment of the wider economic benefits of roads, which is an important political imperative for road investment, is also made more difficult. Two conclusions are reached. Variable trip matrix methods need to be introduced for the appraisal of major road schemes, and scheme appraisal needs to be complemented by a more strategic area-wide approach to evaluation. In responding to its advisory committee (SACTRA), the UK Department of Transport has accepted the first of these conclusions and is cautiously favourable to the second.     

意大利铁路E.464型电力机车

E.464型电力机车专门用来牵引地区以及地区之间的旅客列车,它只有一端司机室.其总需求量为140台,首批订购了40台.该型机车采用三相交流异步牵引电动机,主电路元件为GTO,采用去离子水与乙二醇的混合液体冷却.文章介绍了该型机车的主要技术参数,给出了牵引特性曲线,分析了结构特点.     

货车制造用现代结构材料

1 货车质量 俄罗斯运用敞车的载重量为68～70 t,车辆自重为22 t,轴重为22.5 t,车辆毛重为90 t,载重量与车辆自重比为3.09～3.18.而美国批量生产的敞车载重量为106～110 t,自重为19～20 t,轴重为32.5 t,车辆毛重130 t,载重量与自重之比为5.5～5.65(表1).     

美国铁路车钩缓冲装置的发展（续完）

3　关节式连接器和牵引杆3.1　关节式连接器 　　关节式连接器在客车上已有多年的使用历史，主要用于20世纪30年代一些轻型流线型客车上，但很少在货车上运用。1968年为切萨皮克*俄亥俄铁路制造的活顶漏斗车，其车体间的连接采用由美国铸钢公司研制的关节式连接器，不过并没有收到此类车的订单。20世纪70年代后期，开始使用长途拖车，这时使用单节具有足够长度的车体运载2个拖车已不再合理。虽然可以制造用于运载单节拖车的较短的普通车辆，但这种车辆不能有效利用2个四轮转向架的承载能力。1977年制造出了采用关节式连接器、6节编组的列车，每个车体都运载1个拖车。关节式连接器以切萨皮克*俄亥俄漏斗车连接器为设计原型，相邻车体共同支承在1台四轮转向架上，允许相互间在水平和垂直方向上有一定转角。位于端部2节车的外端以常规方式支撑在独立的转向架上。这样，6节车体（1个车组）仅由7台转向架支承，如按普通结构则需要12台转向架。这种车每辆有10个车体，取得了很大成功。     

EH200型直流供电电力机车的开发

介绍EH200型直流供电电力机车的开发.为证实机车性能满足基本要求,至2001年6月完成了样机试验,并从2001年7月至2002年3月牵引列车进行了运营.通过这些试验和运营,证实该种机车能满足规定的性能,包括与地面设施的匹配.     

An interpretation of inter-container port relationships from the demand perspective

Container ports serve as important conduits to facilitate the efficient flow of containerized cargo. As part of value-driven chain systems that intersect between hinterlands, efficiency gains that are generated within the container port will have a direct impact on the competitive advantage of its users and affect the economic potential of both the origin and destination hinterlands. As such, the paper proposes the usage of indifference analysis propounded in microeconomic theory as a useful means to examine inter-container port competition and complementarity. The framework presented can also be combined with Porter's 'Diamond' model in order for inter-container port demand relationships to be quantified, measured and analysed in an holistic manner. Apart from analysing inter-port relationships from the standpoint of container ports, the framework can also be used to analyse inter-port relationships from the perspective of other key players in the value-driven chain system and modified accordingly to incorporate various indicators that are deemed to be relevant to these parties.     

货车焊接结构疲劳寿命预测研究

基于国际焊接学会标准和英国标准,结合有限元静强度结果和实测载荷谱,对某出口运煤车车体关键部位典型焊接接头形式进行了疲劳寿命对比分析。结果表明,合理选择焊接接头形式和焊接工艺可以成倍地提高结构的疲劳寿命。     

Interaction study of train-bridge-track systems using Maxwell model

The investigation of problems related to the interaction of train, bridge and track systems has been accelerated by the emergence of high-speed trains. Such studies are required, not only for the endurance issues regarding bridge and tracks, but to assure trains' functionality and performance. The suspension mechanism of train systems is of prime importance in defining the functionality of high-speed trains, and accurate mathematical models of the mechanism are imperative. This paper introduces a numerical technique for an interaction study of train-bridge-track systems based on Maxwell (three-element type) modeling of the suspension mechanisms of vehicles. Track irregularity in sinusoidal form is also integrated into the mathematical model. Although the proposed technique is simple in formulation, it offers phenomenal accuracy in representing the interaction of train, track and bridge systems. In a numerical example, the dynamic behavior of a train-bridge system has been studied. Results of this analysis provide a valuable insight into the contributing roles of different parameters in this subject.     

现代机车电传动仿真工具

现代机车动车是一个很复杂的系统,在开发过程中,机械、电子技术和调节技术的专家们必须密切合作.如果既要交换输入数据和结果,又要子系统模型相互直接连接,那么现代仿真工具能极有效地支持这种开发过程.