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211.
ABSTRACT Current cycle-network planning (CNP) at the local level tends to be dominated by a subjective-pragmatic approach in which it is only possible to consider a limited number of route alignment possibilities and development-sequencing scenarios. Although this method may produce acceptable results, it may also be true that the final design could be improved – and the construction efficiency could be enhanced – by a more comprehensive review of the available options in relation to the objectives of the intervention. Such objectives may include accident reduction, modal shift in favour of cycling, health benefits or strategic expansion of a network. This article presents work undertaken to demonstrate a holistic approach to CNP, based on a logically defined spatio-temporal model and allowing some semi-automated multiobjective optimization of network designs in a GIS-based decision-support system. The model is introduced briefly before a case study applying this model to development of a cycle network in a small town in northeast England is described. The results obtained from this case study and the implications of this research for cycle network planners are discussed. 相似文献
212.
Most economic models assume that individuals act out their preferences based on self-interest alone. However, there have also been other paradigms in economics that aim to capture aspects of behavior that include fairness, reciprocity, and altruism. In this study we empirically examine preferences of travel time and income distributions with and without the respondent knowing their own position in each distribution. The data comes from a Stated Preference experiment where subjects were presented paired alternative distributions of travel time and income. The alternatives require a tradeoff between distributional concerns and the respondent’s own position. Choices also do not penalize or reward any particular choice. Overall, choices show individuals are willing forgo alternatives where they would be individually well off in the interest of distributional concerns in both the travel time and income cases. Exclusively self-interested choices are seen more in the income questions, where nearly 25 % of respondents express such preferences, than in the travel time case, where only 5 % of respondents make such choices. The results also suggest that respondents prioritize their own position differently relative to regional distributions of travel time and income. Estimated choice models show that when it comes to travel time, individuals are more concerned with societal average travel time followed by the standard deviation in the region and finally their own travel time, while in the case of income they are more concerned with their own income, followed by a desire for more variability, and finally increasing the minimum income in their region. When individuals do not know their fate after a policy change that affects regional travel time, their choices appear to be mainly motivated by risk averse behavior and aim to reduce variability in outcomes. On the other hand, in the income context, the expected value appears to drive choices. In all cases, population-wide tastes are also estimated and reported. 相似文献
213.
Stated choice experiments have proven to be a powerful tool in eliciting preferences across a broad range of choice settings.
This paper outlines the elements of a group-based experiment designed for interdependent urban freight stakeholders, along
with the procedure to administer the questionnaire sequentially. The focus is on the design of a computer-assisted personal
survey instrument and the value in disseminating the details of a new approach to design and collect stated choice data for
interacting agents. The paper also discusses how to specify a reference alternative, and then how to recruit appropriate real-market
or representative decision-making group members to participate in a subsequent phase of the survey, which incorporates the
reference alternative and contextual information from an initial phase. The empirical strategy, set out in some detail, provides
a new framework within which to understand more fully the role that specific attributes, such as variable user charges, influencing
freight distribution chains might play, and who in the supply chain is affected by specific attributes in terms of willingness
to pay for the gains in distribution efficiency.
相似文献
Andrew CollinsEmail: |
214.
Through the implementation of the Bunker Adjustment Factor (BAF), a shipowner is able to transfer the risk of fuel price fluctuation to the shipper. This and other surcharges are generally undesired by shippers who must pay this fee. The research presented provides an alternative method of risk management that is more effective than the current method, while responding to customer service demands for simplified tariffs. By strategic use of commodity futures, the shipowner is able to better reduce his/her risk exposure, transferring it to willing parties at the futures exchanges, thereby eliminating the need for the bunker surcharge. 相似文献
215.
Jorge Augusto Martins Gonçalves Licinio da Silva Portugal Carlos David Nassi 《Transportation Research Part A: Policy and Practice》2009,43(1):13-25
The objective of this work is to formulate a structure of procedures to support projects to integrate neighborhoods in the area of influence of railway corridors and the urban facilities around each station. Based on the concept of centrality, formulated mathematically by graph theory and with the support of a geographic information system (GIS), we propose interventions aiming to create a more harmonious urban environment better in tune with sustainable mobility. We highlight the relevance of quantitative approaches in the study of urban concepts to foster integration between transportation and urban development, as well as the potential of their application in various Brazilian metropolises having commuter rail systems that are currently underutilized and in the process of revitalization. 相似文献
216.
Zooplankton communities were studied in southeastern Beaufort Sea (Arctic Ocean) in September–October 2002. Cluster analysis and non-metric multidimensional scaling revealed three distinct mesozooplankton assemblages. A neritic assemblage occurred on the Mackenzie Shelf and in Franklin Bay, while distinct off-shelf assemblages prevailed in the Cape Bathurst Polynya and on the Beaufort Slope respectively. Over 95% of the mesozooplankton was comprised of eight copepod taxa. Pseudocalanus spp. contributed predominantly to the discrimination of the three assemblages and was the only significant indicator of the Shelf assemblage. Oithona similis, Oncaea borealis, Metridia longa and Calanus hyperboreus were indicators of the Polynya assemblage. Cyclopina sp. and Microcalanus pygmaeus were indicative of the overall off-shelf community (Polynya and Slope assemblages). The importance of omnivores and carnivores increased from the shelf to the polynya and the slope. Station depth and duration of reduced ice conditions during summer (< 50% ice concentration) underpinned the distribution of the assemblages (r2 = 0.71 and 0.45 respectively). The abundance of Pseudocalanus spp. was independent of depth and increased with the duration of reduced ice conditions (rs = 0.438). The abundance of Cyclopina sp., M. pygmaeus and other indicators of the offshore assemblages followed the opposite trend (rs = − 0.467 and − 0.5 respectively). Under continued climate warming, a reduction of the ice cover will affect the biogeography of mesozooplankton on and around the Mackenzie Shelf, to the potential advantage of Pseudocalanus spp. and other calanoid herbivores. 相似文献
217.
Kaiyu Chen David G. Beale 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2003,39(3):227-244
Summary A MacPherson suspension mechanism is modeled as a two degrees of freedom spatial mechanism. Its dynamic response under two excitement forces is simulated with the motion equations in Euler Parameters with the off-the-center-of-mass body-fixed coordinates derived in this paper. Simulation results are sampled and input into a numerical estimation routine based on singular value decomposition (SVD). Accurate numerical estimation results are achieved. A set of base dynamic parameters in symbolic expressions is also derived from the numerical results utilizing the concepts of mass transfer and moments of inertia transfer. This makes it possible to apply the estimation results to any MacPherson suspension mechanism with the same joint configuration. The potential applications of the symbolic base dynamic parameters in suspension design are also considered. 相似文献
218.
集装箱航运业遭遇种种难题可以理解船东和集装箱航运公司担心舱位运力的增长的速度将远远超出人们最乐观的需求预测。但是为何许多托运人也在担心这种情况呢? 相似文献
219.
Traffic delay caused by incidents is closely related to three variables: incident frequency, incident duration, and the number of lanes blocked by an incident that is directly related to the bottleneck capacity. Relatively, incident duration has been more extensively studied than incident frequency and the number of lanes blocked in an incident. In this study, we provide an investigation of the influencing factors for all of these three variables based on an incident data set that was collected in New York City (NYC). The information about the incidents derived from the identification can be used by incident management agencies in NYC for strategic policy decision making and daily incident management and traffic operation. In identifying the influencing factors for incident frequency, a set of models, including Poisson and Negative Binomial regression models and their zero‐inflated models, were considered. An appropriate model was determined based on a model decision‐making tree. The influencing factors for incident duration were identified based on hazard‐based models where Exponential, Weibull, Log‐logistic, and Log‐normal distributions were considered for incident duration. For the number of lanes blocked in an incident, the identification of the influencing factors was based on an Ordered Probit model which can better capture the order inherent in the number of lanes blocked in an incident. As identified in this study, rain is the only factor that significantly influenced incident frequency. For incident duration and the number of lanes blocked in an incident, various factors had significant impact. As concluded in this study, there is a strong need to identify the influencing factors in terms of different types of incidents and the roadways where the incidents occured. 相似文献
220.