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Abstract The concepts of optimal strategy and hyperpath were born within the framework of static frequency-based public transport assignment, where it is assumed that travel times and frequencies do not change over time and no overcrowding occurs. However, the formation of queues at public transport stops can prevent passengers from boarding the first vehicle approaching and can thus lead to additional delays in their trip. Assuming that passengers know from previous experience that for certain stops/lines they will have to wait for the arrival of the 2nd, 3rd, …, k-th vehicle, they may alter their route choices, thus resulting in a different assignment of flows across the network. The aim of this paper is to investigate route choice behaviour changes as a result of the formation and dispersion of queues at stops within the framework of optimal travel strategies. A new model is developed, based on modifications of existing algorithms. 相似文献
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The logit modeling methodology is applied to include transit access mode choices in conjunction with the automobile vs. transit travel choice decision. The practical problems that arise when the choice set expands beyond two alternatives are identified and addressed. In particular, the complexities that must be resolved in order to use ULOGIT or a similar program include the definition of independent choices (the Independence of Irrelevant Alternatives Property (IIA)), a sequential binary or multinomial logit model (MNL) structure, specification and testing of variables, and the potential for transferring the model to new areas for transportation planning purposes. It was found that the available options cannot be reduced to a single modeling strategy. However, the analysis showed certain concepts which can reduce the uncertainties in related applications of the logit model. It was determined that as many independent choices as possible should be hypothesized and tested for inclusion in the model, but the IIA must be carefully considered because it limits the number of choices that can be represented. Although binary calibration techniques are conceptually appealing, the large number of calibrations for studies involving more than three alternatives suggests that the MNL approach is most practical. Application of the MNL model requires that not only must variables be selected that best explain choice, but they must also be placed in the disutility function of the specific mode or modes to which they are most unique. Finally, it was shown that if choice sets and homogeneous market segments are properly defined, the models can be transferred among different urban areas even though the urban areas exhibit different aggregate characteristics. All observations lead to the general conclusion that the logit modeling methodology can now best be advanced with implementation experience. 相似文献
246.
Deregulating European aviation — A case study 总被引:1,自引:0,他引:1
Sean D. Barrett 《Transportation》1989,16(4):311-327
European international scheduled aviation has been characterised by bans on market entry, price collusion, and capacity sharing. High fares were charged compared to world standards and the fares charged by European charter airlines.In May 1986 new entrants with pricing freedom were permitted on the London-Dublin route which was then the third largest in European scheduled international aviation. Prior to deregulation the route experienced high fare growth. The unrestricted fare ex-London increased 72.6 per cent compared to a Retail Price Index increase of 41.5 per cent. There was a growth in passenger numbers in the years 1980–85 of 2.8 per cent.Since deregulation passenger numbers have risen to 2.3 million compared to 994,000 before deregulation. Fares have declined by an estimated 37 per cent ex-Dublin and 42 per cent ex-London in real terms. There have been four cases of market entry and one of market exit. The estimated share of the new entrants in the second half of 1989 was 28 per cent. The preregulation earnings data of Aer Lingus, the market leader, indicated that protection allowed staff to earn economic rents. A two-tier structure was introduced in response to competition.Remaining barriers to contestability in UK/Ireland aviation include hub airport dominance, ground handling monopolies, and the ability of airlines with routes in both regulated and deregulated markets to engage in geographical price discrimination against airlines with routes in deregulated markets only. A pro-contestability aviation policy in Europe will require measures to prevent the abuse of dominant positions by established airlines over new market entrants and to prevent collusion between established airlines. 相似文献
247.
An empirical investigation on the dynamic processes of activity scheduling and trip chaining 总被引:1,自引:0,他引:1
Investigation of the dynamic processes of activity scheduling and trip chaining has been an interest of transportation researchers over the past decade because of its relevance to the effectiveness of congestion management and intelligent transportation systems. To empirically examine the processes, a computerized survey instrument is developed to collect household activity scheduling data. The instrument is unique in that it records the evolution of activity schedules from intentions to final outcomes for a weekly period. This paper summarizes the investigation on the dynamic processes of activity scheduling and trip chaining based on data collected from a pilot study of the instrument. With the data, ordered logit models are applied to identify factors that are pertinent to the scheduling horizon of activities. Results of the empirical analysis show that a daily schedule often starts with certain activities occupying a portion of the schedule and other activities are then arranged around these pre-occupants. Activities of shorter duration are more likely to be opportunistically inserted in a schedule already anchored by their longer duration counterparts. Persons with children often expect more constraining activities than those with no children. The analysis also shows that female respondents tend to be more structured in terms of how the week is planned. Additionally, analysis of travel patterns reveals that many trip-chains are formed opportunistically. Travel time required to reach an activity is positively related to the scheduling horizon for the activity, with more distant stops being planned earlier than closer locations. 相似文献
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As the problem of full transit vehicles is encountered daily by passengers in most of the big cities, previous research evaluated the consequence of overcrowding in terms of on‐board crowding and passengers not being able to board with full vehicles. The impact of overcrowding in the real world is, however, not necessarily proportional to these numbers. This paper attempts to specify the critical lines and stations of a network by considering the number of passengers failing to board and attempting to evaluate its impact on service quality and safety risks. The hypothesis is that larger stations with wider platforms can often cope better with overcrowding than smaller stations. Therefore a station size dependent satisfaction function is proposed, which takes values from 0 to 1. The method is applied to London's underground network with a number of scenarios which show critical stations in the network if delays occur. 相似文献
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Explaining obesity with urban form: a cautionary tale 总被引:1,自引:0,他引:1
Tudor D. Bodea Laurie A. Garrow Michael D. Meyer Catherine L. Ross 《Transportation》2008,35(2):179-199
In recent years, there has been a dramatic increase in studies exploring associations between the built environment and obesity.
Many studies have found that built environment characteristics, such as high-density land developments, mixed-land uses, and
connected street networks, are associated with lower rates of obesity. However, depending on the research field and the researcher,
how one specifies the experimental model and how sociodemographic characteristics of the population are defined and included
in the model has led to different policy conclusions and implications. This is not a surprising observation; however, it is
one that does seem to have been lost in current discussions. This article highlights several data-processing, model-specification,
and model-estimation factors that should be comprehensively considered in studies of the built environment and obesity. Empirical
results based on data from Atlanta, GA, USA, illustrate that the association between the built environment and obesity is
sensitive to how age, income, and educational attainment are included in the model. Also, a detailed examination of land-use-mix
measures shows that it is difficult to create this measure and that results are sensitive to the treatment of missing values.
Models that distinguish between overweight and obese individuals are shown to provide richer insights into the associations
among obesity, built environment, and sociodemographic characteristics for the Atlanta area. The article concludes by offering
modeling recommendations for future studies.
Tudor D. Bodea is a doctoral student in the School of Civil and Environmental Engineering at the Georgia Institute of Technology. His doctoral work examines the integration of customer-choice models into optimization algorithms for travel-industry applications. Laurie A. Garrow is an assistant professor in the School and Civil and Environmental Engineering at the Georgia Institute of Technology. Her research addresses the development and application of advanced models of travel demand that integrate discrete choice, econometric, and market research methods to enhance understanding of travel behavior. Michael D. Meyer is professor in the School of Civil and Environmental Engineering and Director of the Georgia Transportation Institute at the Georgia Institute of Technology. He has written over 160 technical articles and has authored or coauthored numerous texts on transportation systems, planning, and policy, including a college textbook. In 2006, he was the chairman of the Transportation Research Board Executive Committee. Catherine L. Ross is Harry West professor in the City and Regional Planning Program and Director of the Center for Quality Growth and Regional Development at the Georgia Institute of Technology. She has published extensively in the fields of urban planning, transportation planning, and public participation. She is the coauthor of The Inner City: Urban Poverty and Economic Development in the next Century. 相似文献
Laurie A. GarrowEmail: |
Tudor D. Bodea is a doctoral student in the School of Civil and Environmental Engineering at the Georgia Institute of Technology. His doctoral work examines the integration of customer-choice models into optimization algorithms for travel-industry applications. Laurie A. Garrow is an assistant professor in the School and Civil and Environmental Engineering at the Georgia Institute of Technology. Her research addresses the development and application of advanced models of travel demand that integrate discrete choice, econometric, and market research methods to enhance understanding of travel behavior. Michael D. Meyer is professor in the School of Civil and Environmental Engineering and Director of the Georgia Transportation Institute at the Georgia Institute of Technology. He has written over 160 technical articles and has authored or coauthored numerous texts on transportation systems, planning, and policy, including a college textbook. In 2006, he was the chairman of the Transportation Research Board Executive Committee. Catherine L. Ross is Harry West professor in the City and Regional Planning Program and Director of the Center for Quality Growth and Regional Development at the Georgia Institute of Technology. She has published extensively in the fields of urban planning, transportation planning, and public participation. She is the coauthor of The Inner City: Urban Poverty and Economic Development in the next Century. 相似文献