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41.
A grid based modelling approach akin to cellular automata (CA) is adopted for heterogeneous traffic flow simulation. The road space is divided into a grid of equally sized cells. Moreover, each vehicle type occupies one or more cell as per its size unlike CA traffic flow model where each vehicle is represented by a single cell. Model needs inputs such as vehicle size, its maximum speed, acceleration, deceleration, probability constants, and arrival pattern. The position and speed of the vehicles are assumed to be discrete. The speed of each vehicle changes according to its interactions with other vehicles, following some stochastic rules depending on the circumstances. The model is calibrated and validated using real data and VISSIM. The results indicate that grid based model can reasonably well simulate complex heterogeneous traffic as well as offers higher computational efficiency needed for real time application. 相似文献
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Fekih Mariem Bellemans Tom Smoreda Zbigniew Bonnel Patrick Furno Angelo Galland Stéphane 《Transportation》2021,48(4):1671-1702
Transportation - Spatiotemporal data, and more specifically origin–destination matrices, are critical inputs to mobility studies for transportation planning and urban management purposes.... 相似文献
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Subasish Das Bradford K. Brimley Tomás E. Lindheimer Michelle Zupancich 《国际交通安全学会研究报告》2018,42(3):143-151
Most of the information necessary for driving a vehicle is regarded as visual information. In spite of its importance, visibility conditions at the time of a crash are often not documented at a high level of detail. Past studies have not examined the quantified values of visibility and its association with crashes. The current study merged data collected from the National Oceanic and Atmospheric Administration (NOAA) with 2010–2012 Florida crash data. From the thousands of logged weather events compiled by the NOAA, the researchers isolated periods of normal visibility and comparable periods of reduced visibility in a matched-pairs study. The NOAA data provided real visibility score based on the spatiotemporal data of the crashes. Additionally, the crash data, obtained from Roadway Information Database (RID), contains several geometric and traffic variables that allow for effects of factors and visibility. The study aims to associate crash occurrence under different levels of visibility with factors included in the crash database by developing ordinal logistic regression. The intent is to observe how different visibility conditions contribute to a crash occurrence. The findings indicate that the likelihood of a crash increase during periods of low visibility, despite the tendency for less traffic and for lower speeds to prevail during these times. The findings of this study will add valuable knowledge to the realm of the impact of visibility in the way of using and designing appropriate countermeasures. 相似文献
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Transportation - This study examines to what extent travel information can be used to direct travelers to system-optimal routes that may be sub-optimal for them personally, but contribute to... 相似文献
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Transportation - Traffic congestion is a common phenomenon in road transportation networks, especially during peak hours. More accurate prediction of dynamic traffic flows is very important for... 相似文献
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ABSTRACTIn this paper, the research concentrates on the intermodal land transportation systems which link Antwerp and Rotterdam with a shared hinterland in the long and medium distance range. It uses a choice-based experiment which has been calibrated on the basis of real case studies to understand shipper’s choices between end-to-end chains. The stated choices reveal shippers’ preferences when needing to choose between two logistic pathways, which employ a similar multimodal composition of transport modes to bring the container from door-to-door, but which route the container differently through alternative maritime gateways. The study therefore touches upon the topic of port competition applying a value-driven supply chain approach. Despite narrow differences on the main performance criteria of the door-to-door chains, the empirical analysis proves that shippers are not loyal to one of the ports, but give preference to the lowest cost solution. Enhancing the frequency levels of the inland transportation solution is only at the benefit of the more costly chain. The findings reiterate the importance of intermodal land transport systems in the competition between load centres. 相似文献
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Travel information continues to receive significant attention in the field of travel behaviour research, as it is expected to help reduce congestion by directing the network state from a user equilibrium towards a more efficient system optimum. This literature review contributes to the existing literature in at least two ways. First, it considers both the individual perspective and the network perspective when assessing the potential effects of travel information, in contrast to earlier studies. Secondly, it highlights the role of bounded rationality as well as that of non-selfish behaviour in route choice and in response to information, complementing earlier reviews that mostly focused on bounded rationality only. It is concluded that information strategies should be tailor-made to an individual's level of rationality as well as level of selfishness in order to approach system-optimal conditions on the network level. Moreover, initial ideas and future research directions are provided for assessing the potential of travel information in order to improve network efficiency of existing road networks. 相似文献
49.
George Sammour Tom Bellemans Koen Vanhoof Davy Janssens Bruno Kochan Geert Wets 《Transportation》2012,39(4):773-789
This research paper aims at achieving a better understanding of rule-based activity-based models, by proposing a new level of validation at the process model level in the A Learning-based Transportation Oriented Simulation System (ALBATROSS) model. To that effect, the work activity process model, which includes six decision steps, has been investigated. Each decision step is evaluated during the prediction of the individuals?? schedules. There are specific decision steps that affect the execution pattern of the work activity process model. So, the comportment of execution in the process model contains activation dependency. This branches the execution and evaluation of each agent under examination. Sequence Alignment Methods (SAM) can be used to evaluate how similar/dissimilar the predicted and observed decision sequences are on an agent level. The original Chi-squared Automatic Interaction Detector decision trees at each decision step utilized in ALBATROSS are compared with other well known induction methods chosen to appraise the purpose of the analyses. The models are validated at four levels: the classifier or decision step level whereby confusion matrix statistics are used; The work activity trips Origin?CDestination matrix level; the time of day work activity start time level, using a correlation coefficient; and the process model level, using SAM. The results of validation on the proposed process model level show conformity to all validation levels. In addition, the results provide additional information in better understanding the process model??s behavior. Hence, introducing a new level of validation incur new knowledge and assess the predictive performance of rule-based activity-based models. And assist in identifying critical decision steps in the work activity process model. 相似文献
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Ancor Suárez-Alemán Tomás Serebrisky Oscar Ponce De León 《Maritime Policy and Management》2018,45(5):665-683
Appropriate port regulation and competitive forces tend to be related to higher levels of operational and economic performance of ports. From a policy-making perspective, pursuing efficiency and securing competition in ports to reach a level playing field is a two-step process requiring (1) ex-ante regulations to set the rules that maximize the competition for the market, especially when the policy objective is to attract private operations to ports on competitive concession processes and (2) ex-post competition policy to monitor and preserve competition in the market. This paper studies port regulation in Latin America and the Caribbean (LAC) from a competition perspective, analyzing both ex-ante and ex-post policies implemented in the region. The analysis reveals that the competitive environment in LAC is low, giving room for possible anticompetitive practices in the LAC port sector. Since the end of the 1990s, approximately 80% of container terminals in the region were granted to only five companies. Chile and Mexico have been found to be the best practices in the region, with better conditions assuring robust competition in the market. The main policy implication from this analysis is the need for a stronger involvement of antitrust agencies throughout the port concession processes. 相似文献