Road profile input estimation in vehicle dynamics simulation

Vehicle motion simulation accuracy, such as in accident reconstruction or vehicle controllability analysis on real roads, can be obtained only if valid road profile and tire-road friction models are available. Regarding road profiles, a new method based on sliding mode observers has been developed and is compared with two inertial methods. Experimental results are shown and discussed to evaluate the robustness of our approach.     

停车诱导信息系统条件下的城市交通网络SUE配流模型及算法

停车诱导信息系统(Parking Guidance Information System,PGIS)被认为是改善城市交通拥挤的一项有效技术,不同的PGIS市场占有率对道路交通的影响是不同的。文章将出行者分成两类:使用PGIS和不使用PGIS,考虑了PGIS对出行者道路和停车选择行为的影响以及PGIS的市场占有率,构造了随机用户均衡模型来描述PGIS条件下的道路和停车选择问题,设计了相应的算法。最后,通过一个算例对模型及算法进行了验证。     

Pooling for the journey to work: The outlook in Great Britain

Pooling, or ride-sharing, is a term coined in the United States (U.S.) to describe various forms of collective travel organised for, and often by, specific groups of commuters with similar travel requirements. Its different forms include bus pooling (financially self-supporting works bus or commuter coach services), minibus pooling (van pooling in U.S. terminology) and car pooling. It has been claimed that these forms of collective travel offer a more personalised service than conventional stage carriage buses, and therefore have a greater chance of attracting solo car drivers and increasing vehicle occupancies. This, in turn, can lead to lower fuel consumption and reduced traffic congestion at peak times. Following the advent of oil shortages in the winter of 1973/74, considerable efforts were made in the U.S. to promote pooling initiatives. This gave rise to the publication of a substantial volume of literature that sometimes indicated significant resource-saving achievements. This paper considers the potential for bus, minibus and car pooling in Great Britain, drawing both on relevant theoretical and economic studies, and on practical operational experience. It concludes that under reasonable assumptions about the transport situation in the next decade or so, pooling could become increasingly useful for solving the travel problems of individual local groups, but that it is unlikely to become a major mode in terms of the numbers of trips carried. The effects of recent legislative changes are discussed, and the justification for further change assessed. Relevant comparisons are made with the U.S.Crown Copyright 1983. Extracts from the text may be reproduced, except for commercial purposes, provided the source is acknowledged.     

The Port of Baltimore: off the beaten track?

The Port of Baltimore has recently experienced alarming traffic trends. Most measures of port vitality have been going the wrong way—tonnage, ship calls, market share, steamship service. rail service. Baltimore has been squeezed by external forces and circumstances. Dergulated rail and truck rates have not favoured Baltimore, nor have railroad mergers that have led to rail traffic concentrations at rival seaports. Federal approval of dredging projects has been delaed. Crises in the labour market have created a climate of uncertainty. Global trade patterns and intermodel itineraries have shifted, again, it seems, not to Baltimore'advantage. Baltimore needs new public port policy recommendations. This paper explains some of the problems and offers preliminary suggestions.     

Physical characteristics of paratransit in developing countries of Asia

Paratransit modes play a significant role in the urban transport sectors of developing countries since in many cities more than half of the total public transport demand are carried by them. Rapid increase in urban population, per capita income, along with inadequate existing transport infrastructures have stimulated their usage as cheap and convenient public transport modes. This paper examines their present role and physical characteristics in a comparative form to provide a basic data for discussion of urban transport issues in developing cities.     

Ultimate strength design of stiffened plates under axial compression and bending

The basis for design of stiffened plates under longitudinal compression is outlined and predictions using several codes are compared against numerical results from an inelastic beam-column formulation and test results. In order to explore the inherent differences in column behaviour separately from discrepancies arising due to plate panel behaviour, the code predictions are re-evaluated adopting a common plate panel effective width formulation. On this basis, a critical review of code methods is made and some modifications are proposed.

The effect of the magnitude and direction of applied uniform bending on the axial capacity of stiffened plates is investigated by comparing two alternative design approaches, namely an interaction equation and a method based on the Perry equation, against results from numerical analyses and from rigid plastic theory. The interaction equation is invariably more conservative than the Perry approach but its simplicity tends to be convenient for routine design applications. Finally, results of numerical analyses, together with experimental results from previous studies, on continuous stiffened plates under combined axial compression and lateral pressure are presented and available design guidance is discussed.     

Heavy goods vehicle taxation in the United Kingdom

Heavy goods vehicle taxation has been the subject of considerable debate in U.K. over the past 15 years. There have been a number of attempts to relate the taxes paid by heavy goods vehicles to the public costs incurred to provide road track for their use. This paper reviews critically the position taken in the last public account of allocation procedures and also outlines recent modifications to the approach. It is suggested that the allocation of public costs is sensitive to some of the assumptions made and that this may result in an over-estimation of the costs associated with road haulage activities. A number of comparative calculations are made using data from both 1975/76 and more recent years to examine this hypothesis.