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261.
This paper reviews the economic literature relating to aviation safety; analyzes the safety record of commercial passenger aviation in the United States and abroad; examines aviation security as a growing dimension of aviation safety; and identifies emerging issues in airline safety and challenges for aviation safety research. Commercial airline safety has improved dramatically since the industry's birth over a century ago. Fatal accident rates for large scheduled jet airlines have fallen to the level where (along many dimensions) aviation is now the safest mode of commercial transportation. However, safety performance has not been evenly distributed across all segments of commercial aviation, nor among all countries and regions of the world. The finding that developing countries have much poorer safety records has been a persistent conclusion in aviation safety research and continues to be the case. Unfortunately, operations data are not available for many of the airlines that experience fatal accidents, so it is not possible to calculate reliable fatality rates for many segments of the worldwide aviation industry. Without more complete information, it will likely be difficult to make substantial improvements in the safety of these operations. Challenges to improving aviation security include: how much to focus on identifying the terrorists as opposed to identifying the tools they might use; determining how to respond to terrorist threats; and determining the public versus private roles in providing aviation security. The next generation of safety challenges now require development and understanding of new forms of data to improve safety in other segments of commercial aviation, and moving from a reactive, incident-based approach toward a more proactive, predictive and systems-based approach. 相似文献
262.
John Loomis 《Coastal management》2013,41(4):387-404
This article demonstrates how benefit transfer can quantify tourism and existence values. Existing literature values of sea otters and a meta analysis yield benefit estimates of several million dollars for the increased number of sea otters expected by USFWS in the next decade if the “no otter zone” is eliminated and otters allowed to expand along the Santa Barbara coast. These benefit estimates of sea otter expansion exceed the costs to commercial fishing. Thus the benefit transfer approach can contribute to a more complete economic analysis of endangered species recovery or critical habitat efforts than the current USFWS approach. 相似文献
263.
Scott McCreary John Gamman Bennett Brooks Lisa Whitman Rebecca Bryson Boyd Fuller Austin McInerny Robin Glazer 《Coastal management》2013,41(3):183-216
Conflict is intrinsic to coastal zone management, yet relatively few peer-reviewed studies have examined how coastal managers might apply conflict resolution processes in the coastal zone management (CZM) context. The authors believe that many of these disputes can be addressed by using a structured mediation model that involves face-to-face negotiation with a broad range of stakeholders to build consensus-based agreements for integrated coastal zone management (ICZM). To explore this further, the article examines four questions. First, it examines how CZM literature characterizes conflict and conflict resolution. Second, it looks at how essential principles from the field of alternative dispute resolution and environmental mediation can be best employed in the ICZM context. In particular, it explores the various elements of a stepwise agreement building model, a mediated negotiation process model the authors use in practice that bases its success on a foundation of four principles: representation, participation, legitimacy, and accountability. Next, it details three essential tools used in this process, stakeholder analysis, joint factfinding, and single-text negotiation, that the authors believe to be promising for developing and adopting stable, well-informed, and implementable agreements for ICZM. Finally, the article examines how these structuring principles and process strategies have been used in two recent case studies regarding the management of the San Francisco estuary and its tributaries. 相似文献
264.
Modelling the temporal response of travellers to transport policy interventions has rapidly emerged as a major issue in many
practical transport planning studies and is recognised to hold particular challenges. The importance of congestion and its
variation over the day, together with the emergence of time-dependent road user charging as a policy tool, emphasise the need
to understand whether and how travellers will change the timing of their journeys. For practical planning studies, analysts
face a major issue of relating temporal changes to other behavioural changes that are likely to result from policy or exogenous
changes. In particular, the relative sensitivity of time and mode switching has been difficult to resolve. This paper describes
a study undertaken to determine the relative sensitivity of mode and time of day choice to changes in travel times and costs
and to investigate whether evidence exists of varying magnitudes of unobservable influences in time of day switching. The
study draws on data from three related stated preference studies undertaken over the past decade in the United Kingdom and
the Netherlands and uses error components logit models to investigate the patterns of substitution between mode and time of
day alternatives. It is concluded that the magnitude of unobserved influences on time switching depends significantly on the
magnitudes of the time switches considered. With time periods of the magnitude generally represented in practical modelling,
i.e. peak periods of 2–3 hours, time switching is generally more sensitive in these data than mode switching. However, the
context of the modelling and the extent to which relevant variables can be measured will strongly influence these results. 相似文献
265.
This article uses data from the 2001 National Household Travel Survey (NHTS) to compare travel behavior in rural and urban areas of the U.S. As expected, the car is the overwhelmingly dominant mode of travel. Over 97% of rural households own at least one car vs. 92% of urban households; 91% of trips are made by car in rural areas vs. 86% in urban areas. Regardless of age, income, and race, almost everyone in rural areas relies on the private car for most travel needs. Mobility levels in rural areas are generally higher than in urban areas. That results from the more dispersed residences and activity sites in rural areas, which increase trip distances and force reliance on the car. Somewhat surprisingly, the rural elderly and poor are considerably more mobile than their urban counterparts, and their mobility deficit compared to the rural population average is strikingly less than for the urban elderly and poor compared to the urban average. Data limitations prevented a measurement of accessibility, however, and it seems likely that rural areas, by their very nature, are less accessible than urban areas, especially for the small percentage of car-less poor and elderly households. 相似文献
266.
In this paper, we develop a model of travel in tours that joins several locations by travel through a congested network. We develop a microscopic analysis in continuous time of individual benefits obtained by spending time at each of the locations and costs incurred through travel between them. This is combined with a continuous time macroscopic equilibrium model of travel during congested peak periods to show how individuals' travel choices are influenced by the congestion that result from corresponding choices made by others. We show how different travellers can achieve identical net utilities by making different combinations of choices within the equilibrium. The resulting model can be used to investigate the effect on travel behaviour and individual utility of various transport interventions, and we illustrate this by considering the effect of a peak‐period charge that eliminates congestion. 相似文献
267.
John T. Starr 《Maritime Policy and Management》1991,18(3):171-181
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. 相似文献
268.
269.
John Foster 《Transportation》1973,2(3):321-335
Existing methods of evaluating large-scale transport networks involve the use of mathematical models of traffic flow which are generally both large and complex. However, the time and cost involved in the use of these models normally restricts their use for the detailed forecasting of traffic flows and costs to the assessment of a relatively small number of alternative patterns of overall investment. In order to evaluate the individual projects and groups of projects which go to make up an overall investment plan, it is, therefore, usually necessary to make simplifying assumptions about the influence of any one project on the overall traffic pattern, so as to isolate it from the influence of neighbouring projects. These assumptions generally result in the loss of a certain amount of the detail normally available from a standard model, and the task of assessing the relative value of different projects and the amount of interaction between them is made more difficult.This paper describes a new technique, designed to permit the evaluation of individual projects whilst still retaining the level of detail available from a full-scale mathematical model. The aim has been to produce a cheap and easy-to-use technique, capable of producing substantially the same results as a standard model. The technique uses newly developed computer algorithms which short-cut the full-scale model by forecasting the changes in an existing travel pattern resulting from the influence of a particular project. Initial tests suggest that approaching the problem in this way can save up to 70% of the computing time and costs involved in the use of a standard model for the evaluation of individual projects.The technique as described here is envisaged as a tool for aiding strategic investment decisions. It can, however, provide data for more detailed investigations, and could, with modifications, carry out these investigations on smaller problems than those for which it was originally designed.Crown copyright reserved, 1973 相似文献
270.
It is important to specify accurately the dollar value assigned to time savings, since up to eighty percent of the benefits estimated to accrue from improvements in transportation systems are associated with savings in travel time. In this paper the economic theory of consumer choice is utilized to structure a model that is used to estimate how Value of Time (VOT) measures vary with community-related variables.Parameters for this theoretical model are empirically estimated using data from transportation surveys conducted in Ithaca and Syracuse, New York and Amherst, Massachusetts. The results confirm the validity of the theoretical model and suggest that leisure time, travel cost, and household income level, as well as community population, are important determinants of the marginal value of time. These models are particularly suited for transferring data results obtained in one community to another, thereby saving survey costs, since the resulting VOT estimates are based solely on underlying socio-economic variables and community characteristics that are known for most localities. The methodology is also useful for estimating different VDT's for particular population subgroups, like the elderly, which may be the focus of a particular transportation project. 相似文献