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991.
992.
The French-German research project Bahn.Ville, dealing with Rail oriented development and intermodality in German and French urban regions, has consisted in identifying the principles and factors of success of an urban development oriented towards rail, and in testing them in the agglomeration of Saint-Étienne. One of the research-actions focussed on identifying and anticipating the potential impacts in terms of urban development of a new transport system, of the tram-train type, on an existing railway line. The effect of the insertion of new stops on the global journey time is one of the criterion of the evaluation of new stops. A simulation method of the journey times is presented in this paper. The interest and the limits of this approach, regarding the rolling stock choice and the insertion of new stops, are emphasized. 相似文献
993.
994.
This paper investigates a traffic volume control scheme for a dynamic traffic network model which aims to ensure that traffic volumes on specified links do not exceed preferred levels. The problem is formulated as a dynamic user equilibrium problem with side constraints (DUE-SC) in which the side constraints represent the restrictions on the traffic volumes. Travelers choose their departure times and routes to minimize their generalized travel costs, which include early/late arrival penalties. An infinite-dimensional variational inequality (VI) is formulated to model the DUE-SC. Based on this VI formulation, we establish an existence result for the DUE-SC by showing that the VI admits at least one solution. To analyze the necessary condition for the DUE-SC, we restate the VI as an equivalent optimal control problem. The Lagrange multipliers associated with the side constraints as derived from the optimality condition of the DUE-SC provide the traffic volume control scheme. The control scheme can be interpreted as additional travel delays (either tolls or access delays) imposed upon drivers for using the controlled links. This additional delay term derived from the Lagrange multiplier is compared with its counterpart in a static user equilibrium assignment model. If the side constraint is chosen as the storage capacity of a link, the additional delay can be viewed as the effort needed to prevent the link from spillback. Under this circumstance, it is found that the flow is incompressible when the link traffic volume is equal to its storage capacity. An algorithm based on Euler’s discretization scheme and nonlinear programming is proposed to solve the DUE-SC. Numerical examples are presented to illustrate the mechanism of the proposed traffic volume control scheme. 相似文献
995.
An essential element of demand modeling in the airline industry is the representation of time of day demand—the demand for a given itinerary as a function of its departure or arrival times. It is an important datum that drives successful scheduling and fleet decisions. There are two key components to this problem: the distribution of the time of day demand and how preferred travel time influences itinerary choice. This paper focuses on estimating the time of day distribution. Our objective is to estimate it in a manner that is not confounded with air travel supply; is a function of the characteristics of the traveler, the trip, and the market; and accounts for potential measurement errors in self-reported travel time preferences. We employ a stated preference dataset collected by intercepting people who were booking continental US trips via an internet booking service. Respondents reported preferred travel times as well as choices from a hypothetical set of itineraries. We parameterize the time of day distribution as a mixture of normal distributions (due to the strong peaking nature of travel time preferences) and allow the mixing function to vary by individual characteristics and trip attributes. We estimate the time of day distribution and the itinerary choice model jointly in a manner that accounts for measurement error in the self-reported travel time preferences. We find that the mixture of normal distributions fits the time of day distribution well and is behaviorally intuitive. The strongest covariates of travel time preferences are party size and time zone change. The methodology employed to treat self-reported travel time preferences as potentially having error contributes to the broader transportation time of day demand literature, which either assumes that the desired travel times are known with certainty or that they are unknown. We find that the error in self-reported travel time preferences is statistically significant and impacts the inferred time of day demand distribution. 相似文献
996.
Shaw F. Atiyya Malokin Aliaksandr Mokhtarian Patricia L. Circella Giovanni 《Transportation》2021,48(1):395-429
Transportation - Waiting, whether for services, for someone, or for something, is an inescapable part of life. This paper addresses a gap in the waiting time literature by examining previously... 相似文献
997.
Bhattacharyya Abhinav Jin Wen Le Floch Caroline Chatman Daniel G. Walker Joan L. 《Transportation》2019,46(2):373-393
Transportation - There have been numerous behavior change studies focused on sustainable travel mode choices. In this study we focused on the residential choices that in turn influence travel... 相似文献
998.
This article discusses the current views on the application of road safety audits (RSAs) as a tool for the improvement of road safety and proposes a new method of study for detailed evaluation of some features that can influence their effectiveness. This is demonstrated in the practical setting of RSAs applied to existing road reviews or inspections. Starting from a review of published sources on RSAs in different countries, a set of questions has been identified and a case study undertaken on the impact of alternative RSA procedures on its overall effectiveness. RSA effectiveness is measured both as agreement with a safety expert assessment and to an accident-based study. The main features analyzed in the case study include the type of observer used for data collection and the type of checklist used as a guide to field work. Based on an exploratory study, the performance of RSA application is evaluated using weighted indices of concordance and disagreement, and the rating of detection or omission for the observations gathered in the accident diagnosis of the safety problems at the intersection studied, supplemented by a statistical analysis of the influence of selected covariates on these scores. The main results of the case study can be summarized as clear support to team work for field observation and also to employing less-experienced personnel for field observation. The study also stresses the need for procedures/criteria for priority setting. These conclusions are useful for the selection of alternative RSA procedures in agencies responsible for promoting or enforcing RSA and in professional teams carrying out RSA tasks. Several features deserving further study are also identified. 相似文献
999.
A novel method is presented to improve the recognition rate of warhead in this paper. Firstly, a tool for electromagnetic calculation, like CST Microwave Studio, is used to simulate the frequency response of the electromagnetic scattering. Secondly, the echo and further the range profile are acquired from the frequency response by further processing. Thirdly, a set of discriminative features is extracted from the range profiles of the target. Fourthly, these features are used to construct a dictionary for the sparse representation classifier. Finally, the sample of the target can be classified by solving the sparsest coefficients. Since the reconstruction result is determined by a linear combination of the training samples, this method has a good robustness for the variable features. By formulating the problem within a feature-based sparse representation framework, the presented method combines the discriminative features of each sample during the sparse recovery process rather than in a postprocessing manner. Moreover, based on the feature representation space rather than a single feature or image pixel, the constructed dictionary exhibits both strong expressive and discriminative powers that can enhance the classification performance of the test sample. A series of test results based on the simulated data demonstrates the effectiveness of our method. 相似文献
1000.
在建设公路桥梁时,最重要的是考虑关于安全和耐久两方面的指标。而频繁发生的桥梁安全事故,对于桥梁整体的工程效益有很大的影响,对于交通运输网络的破坏性也是相当明显的。本文将结合具体的工程案例,具体分析桥梁设计中存在的问题,对于提升桥梁设计的安全与耐久性进行探讨。最后提出相应的措施来提升桥梁工程施工质量。希望对以后的类似工程有一定的借鉴作用。 相似文献