The effect of the competition between cars and trucks on the evolution of the motorway transport system

Motorways, which were devised at the beginning of their history as dedicated roads intended to be traveled by cars only, are at present also traveled by considerable flows of trucks. This fact has deeply changed the motorway transport system with respect to its original conception, owing to the interactions between two categories of vehicles whose characteristics are very different. These interactions greatly increase the transport cost perceived by car drivers with respect to truck drivers. This paper studies the consequences of this cost asymmetry on the evolution of the transport system when the geometric characteristics of a motorway remain unchanged in time, while transport demand increases. By using a theoretical model of competition between cars and trucks, it is shown that, if both the geometric characteristics of a motorway and the increase rate of the activities that feed the transport demand remain unchanged over time, the competition between cars and trucks, as well as the fact that in general passengers have better transport alternatives than freight, make the increase rate of truck traffic greater than that of cars, causing a progressive increase in the proportion of trucks in the time periods in which a motorway is traveled by both the vehicle categories. Since truck traffic on motorways, at least in Europe, is very scarce on weekends and in holiday periods, in which motorways are traveled almost only by cars, these results seem to indicate a tendency to the specialization of motorways, which are likely to be used in the future mostly by only one category of vehicles in different periods of time.     

浅谈二手车车况的静态鉴定

本文详细阐述了发动机、底盘、电气设备、车身及驾驶室/行李箱这五部分的静态鉴定,给出了五部分静态鉴定的顺序和它们决定二手车价值的一般比例,对实践具有一定指导作用。     

铁道行业标准《铁道车辆空气弹簧》修订介绍

介绍TB/T2841—2010《铁道车辆空气弹簧》修订的背景及国内外铁道车辆空气弹簧常用标准情况。对照JISE4206:1989《铁路车辆用弹簧装置》、EN13597:2003《铁道车辆用橡胶悬挂部件空气弹簧气囊》及TB/T2841—2005《铁道车辆空气弹簧》,详细说明TB/T2841—2010的适用范围、主要修订内容及主要参数的制定。     

The evening commute with cars and transit: Duality results and user equilibrium for the combined morning and evening peaks

This paper extends Vickrey’s (1969) commute problem for commuters wishing to pass a bottleneck for both cars and transit that share finite road capacity. In addition to this more general framework considering two modes, the paper focuses on the evening rush, when commuters travel from work to home. Commuters choose which mode to use and when to travel in order to minimize the generalized cost of their own trips, including queueing delay and penalties for deviation from a preferred schedule of arrival and departure to and from work. The user equilibrium for the isolated morning and evening commutes are shown to be asymmetric because the schedule penalty in the morning is the difference between the departure and wished curves, and the schedule penalty in the evening is the difference between the arrival and wished curves. It is shown that the system optimum in the morning and evening peaks are symmetric because queueing delay is eliminated and the optimal arrival curves are the same as the departure curves.The paper then considers both the morning and evening peaks together for a single mode bottleneck (all cars) with identical travelers that share the same wished times. For a schedule penalty function of the morning departure and evening arrival times that is positive definite and has certain properties, a user equilibrium is shown to exist in which commuters travel in the same order in both peaks. The result is used to illustrate the user equilibrium for two cases: (i) commuters have decoupled schedule preferences in the morning and evening and (ii) commuters must work a fixed shift length but have flexibility when to start. Finally, a special case is considered with cars and transit: commuters have the same wished order in the morning and evening peaks. Commuters must use the same mode in both directions, and the complete user equilibrium solution reveals the number of commuters using cars and transit and the period in the middle of each rush when transit is used.     

车联网感知技术研究进展

车联网是物联网的具体应用,车联网获取车辆运行参数和道路等交通基础设施使用状况,感知实时道路交通路况,提供丰富的智能交通综合服务.介绍了车联网相关概念及系统构成,总结了车联网的感知关键技术的研究现状,如射频识别(RFID)、无线传感网(WSN)以及两者融合等,包括近期的研究工作,理论成果及实际应用等,探讨了存在的问题和今...     

Assessment of motor vehicle use characteristics in three Indian cities

Estimates of emissions and energy consumption by vehicular fleet in India are not backed by reliable values of parameters, leading to large uncertainties. We report new methods, including primary surveys and secondary data sources, to estimate in-use fleet size, annual mileage (kilometers per year), and fuel efficiency of cars and motorised two-wheelers (MTW) for Delhi, and except fleet size and annual mileage of cars, for Visakhapatnam and Rajkot. We estimated that the official number of registered cars and MTW in Indian cities is more than two times the actual number of in-use vehicles. The private vehicular fleet in India is the youngest, its fuel efficiency one of the highest, and annual kilometers travelled is the lowest, compared to many high-income countries, such as the USA and those in European Union. Along with high renewal rate of fleet, the data suggest that it is possible for India to have one of the most fuel-efficient vehicle fleets in the world in the future, if fuel-efficiency standards and fiscal policies to contain growing dieselization are implemented in the country at the earliest.     

空车调整专家系统的研究

根据铁路货运营销管理对编制空车调整计划的新要求,提出了开发空车调整专家系统的总体结构,论述了用产生式规则和面向对象的方法相结合的知识表示方法和相应的推理机制。     

论我国城市发展私人小汽车的利弊与对策

分析了我国城市发展私人小汽车的利弊,从可持续发展的角度考虑,指出大力发展社区公共自助交通工具,为居民提供门到门、站到站的服务,是当今客运交通的最佳选择。     

浅谈二手车收购估价方法

二手车收购价格是在特定的交易行为中,特定的买方和卖方对二手车商品提供或支付的货币数额。收购估价方法是二手车市场交易中值得深入研究和探讨的关键一环。本文对二手车收购估价常用方法进行了比较系统、客观地阐述,对广大二手车评估收购人员有一定借鉴作用。