美国的城市交通规划

介绍了今后几十年中将影响城市交通规划的一些重要趋势，讨论了今后交通规划者在十个领域可能面临的挑战。     

The simple platoon advancement model of its technologies applied to vehicle control at signalised intersections

The Simple Platoon Advancement (SPA) Model describes a conceptual system whose principal objective is to increase the throughput of vehicles at signalised intersections. This is achieved through a novel combination of Intelligent Transport System (ITS) technologies including Automatic Cruise Control, Lane Departure Avoidance, and Collision Avoidance. These are combined in SPA so that vehicles are progressed through signalised intersections under automated control. All of the vehicles in a stationary queue are moved instantly at the start‐of‐green as a closely‐spaced platoon. Dispersion occurs after all vehicles are in motion. Throughput of the SPA model is determined analytically and comparisons are made between the SPA model and a valid representation of current road traffic behaviour. These comparisons show that theoretically a SPA system can progress nearly twice as many vehicles past the stopline as can be seen in today's road network. Other benefits of a conceptual SPA system are improved safety and a reduction in delay per vehicle.     

Sensitivity analysis on stochastic equilibrium transportation networks using genetic algorithm

This study deals with the sensitivity analysis of an equilibrium transportation networks using genetic algorithm approach and uses the bi‐level iterative sensitivity algorithm. Therefore, integrated Genetic Algorithm‐TRANSYT and Path Flow Estimator (GATPFE) is developed for signalized road networks for various level of perceived travel time in order to test the sensitivity of perceived travel time error in an urban stochastic road networks. Level of information provided to drivers correspondingly affects the signal timing parameters and hence the Stochastic User Equilibrium (SUE) link flows. When the information on road system is increased, the road users try to avoid conflicting links. Therefore, the stochastic equilibrium assignment concept tends to be user equilibrium. The GATPFE is used to solve the bi‐level problem, where the Area Traffic Control (ATC) is the upper‐level and the SUE assignment is the lower‐level. The GATPFE is tested for six‐junction network taken from literature. The results show that the integrated GATPFE can be applied to carry out sensitivity analysis at the equilibrium network design problems for various level of information and it simultaneously optimize the signal timings (i.e. network common cycle time, signal stage and offsets between junctions).     

The decline of the UK merchant fleet: an assessment of government policies in recent years

This paper attempts to outline the evolution of UK shipping policy since the mid 1980s, in the context of the decline of the UK Merchant Marine. It provides an analysis of the action, or inaction, of the UK government during the period up to 1991, and assesses whether a coherent and logical policy has been developed. In so doing it evaluates whether the UK is in line with the actions of the EC and its other maritime competitors in the field of shipping policy and whether, as a consequence, the decline of the Merchant Marine has been actively hindered or helped. An assessment is also made in the light of continuing political developments in the UK, and those predicted for the coming months.     

Maritime sociology: towards a delimation of themes and analytical frameworks

This paper sets out to evaluate the main areas of focus within maritime sociology and to link more closely than hitherto the various substantive discussions with general theoretical and conceptual approaches. More specifically, it suggests directions in which maritime sociology may be advanced at both empirical and conceptual levels in the future.     

The challenge of liberalising domestic airline competition in a less developed country

A new wave of liberalisation of domestic airline competition is taking place in less developed nations, although the initial motivation in most cases is to supplement the capacity of the government's own airline. Liberalisation tends to begin with free market entry and a strong interest in privatisation while other regulatory controls are maintained. This position is untenable and policy makers in the less developed countries are having to learn quickly without the benefit of the detailed analyses that preceded liberalisation in the developed countries. This paper explores these problems and focuses on the lessons that policy makers in the less developed countries can draw from experiences elsewhere.     

East European shipping and economic change: a conceptual model

This paper discusses and assesses the complex process of change that has occurred in East Europe over thc last five years, and attempts to relate these changes to the shipping sector. Conventional mathematical methods are discussed as inappropriate in analysing economic, social and political developments and the technique of conceptual modelling is used, borrowed from other disciplines including those of environmental appraisal and computer sciences. The main linkages are discussed with particular reference to the Polish shipping sector, with specific analysis of the legal, managerial, spatial, economic, political, social and organizational contexts. The dominant themes of change are drawn out in an attempt to predict the impact on the Polish shipping industry in general and the three main State companies-Polish Ocean Lines (Liner Shipping); Polish Steamship Company (Bulk/Tramp) and Polish Baltic Ferries- that dominate the market.     

Some evidence of transit demand elasticities

This paper draws together empirical evidence from a variety of sources about the magnitudes of transit price elasticities and cross-elasticities. A number of different practical measures of demand elasticity are first defined and some expectations about magnitude are discussed. Evidence is then collated from the analysis of transit operating statistics, from experience in demonstration projects and from attempts to develop cross-sectional models of demand and modal choice.In general, all of the limited evidence available suggests that transit demand is inelastic with respect to money price. Typically, ridership is significantly more sensitive to changes in the level of service (particularly door-to-door journey time) than to changes in fare, although service elasticities also are usually numerically less than unity.In broad terms, short-run direct fare elasticities are characteristically observed to lie within the range of -0.1 to –0.7. A more precise value in a particular instance will depend on a variety of factors in ways which largely support a priori notions. Thus in very large cities, central city areas, at peak hours, and in other circumstances where the prices of alternative modes are high, transit fare elasticities are usually numerically at the lower end of the range.Estimates of cross-elasticities (representing the volumes of transit traffic diverted to other modes by transit price increases) are much harder to come by, and in fact only a few very uncertain estimates are presented here.This paper is a condensation of an Urban Institute Working Paper of the same title (WP 708-52, November 1971). Opinions expressed are those of the author and do not necessarily represent the views of The Urban Institute or its sponsors.