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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Network Models In Evacuation Planning

Tarhini, Hussein Ali 03 July 2014 (has links)
This dissertation addresses the development and analysis of optimization models for evacuation planning. Specifically we consider the cases of large-scale regional evacuation using household vehicles and hospital evacuation. Since it is difficult to estimate the exact number of people evacuating, we first consider the case where the population size is uncertain. We review the methods studied in the literature, mainly the strategy of using a deterministic counterpart, i.e., a single deterministic parameter to represent the uncertain population, and we show that these methods are not very effective in generating a good traffic management strategy. We provide alternatives, where we describe some networks where an optimal policy exist independent of the demand realization and we propose some simple heuristics for more complex ones. Next we consider the traffic management tools that can be generated from an evacuation plan. We start by introducing the cell transmission model with flow reduction. This model captures the flow reduction after the onset of congestion. We then discuss the management tools that can be extracted from this model. We also propose some simplification to the model formulation to enhance its tractability. A heuristic for generating a solution is also proposed, and its solution quality is analyzed. Finally, we discuss the hospital evacuation problem where we develop an integer programming model that integrates the building evacuation with the transportation of patients. The impact of building evacuation capabilities on the transportation plan is investigated through the case of a large regional hospital case study. We also propose a decomposition scheme to improve the tractability of the integer program. / Ph. D.
22

Modelling and Appraisal in Congested Transport Networks

West, Jens January 2016 (has links)
Appraisal methodologies for congestion mitigation projects are relatively less well developed compared to methodologies for projects reducing free flow travel times. For instance, static assignment models are incapable of representing the build-up and dissipation of traffic queues, or capturing the experienced crowding caused by uneven on-board passenger loads. Despite the availability of dynamic traffic assignment, only few model systems have been developed for cost-benefit analysis of real applications. The six included papers present approaches and tools for analysing traffic and transit projects where congestion relief is the main target. In the transit case studies, we use an agent-based simulation model to analyse congestion and crowding effects and to conduct cost-benefit analyses. In the case study of a metro extension in Stockholm, we demonstrate that congestion and crowding effects constitute more than a third of the total benefits and that a conventional static model underestimates these effects vastly. In another case study, we analyse various operational measures and find that the three main measures (boarding through all doors, headway-based holding and bus lanes) had an overall positive impact on service performance and that synergetic effects exist. For the congestion charging system in Gothenburg, we demonstrate that a hierarchal route choice model with a continuous value of time distribution gives realistic predictions of route choice effects although the assignment is static. We use the model to show that the net social benefit of the charging system in Gothenburg is positive, but that low income groups pay a larger share of their income than high income groups. To analyse congestion charges in Stockholm however, integration of dynamic traffic assignment with the demand model is necessary, and we demonstrate that this is fully possible. Models able to correctly predict these effects highlight the surprisingly large travel time savings of pricing policies and small operational measures. These measures are cheap compared to investments in new infrastructure and their implementation can therefore lead to large societal gains. / <p>QC 20160829</p>
23

Development of a behaviorally induced system optimal travel demand management system

Hu, Xianbiao, Chiu, Yi-Chang, Shelton, Jeff 30 March 2016 (has links)
The basic design concept of most advanced traveler information systems (ATIS) is to present generic information to travelers, leaving travelers to react to the information in their own way. This passive way of managing traffic by providing generic traffic information makes it difficult to predict the outcome and may even incur an adverse effect, such as overreaction (also referred to as the herding effect). Active traffic and demand management (ATDM) is another approach that has received continual attention from both academic research and real-world practice, aiming to effectively influence people's travel demand, provide more travel options, coordinate between travelers, and reduce the need for travel. The research discussed in this article deals with how to provide users with a travel option that aims to minimize the marginal system impact that results from this routing. The goal of this research is to take better advantage of the available real-time traffic information provided by ATIS, to further improve the system level traffic condition from User Equilibrium (UE), or a real-world traffic system that is worse than UE, toward System Optimal (SO), and avoid passively managing traffic. A behaviorally induced, system optimal travel demand management model is presented to achieve this goal through incremental routing. Both analytical derivation and numerical analysis have been conducted on Tucson network in Arizona, as well as on the Capital Area Metropolitan Planning Organization (CAMPO) network in Austin, TX. The outcomes of both studies show that our proposed modeling framework is promising for improving network traffic conditions toward SO, and results in substantial economic savings.
24

Advanced Traffic Service / Avancerad Trafiktjänst

Löfås, Peter January 2005 (has links)
<p>More and more travellers use navigation-aid software to find the way while driving. Most of todays systems use static maps with little or no information at all about currently yeilding roads conditions and disturbances in the network. It is desirable for such services</p><p>in the future to include information about road works, accidents, surface conditions and other types of events that affects what route is currently the best.</p><p>It is also desirable to notify users about changes in the prerequisites of the chosen route after they have started their trip.</p><p>This thesis investigates methods to include dynamic traffic information in route calculations and notifying users when the characteristics change for their chosen route.</p><p>The thesis utilizes dynamic traffic information from The Swedish Road Agencys (Vägverket) central database for traffic information, TRISS and calculates affected clients with help of positioning through the GSM network.</p>
25

Advanced Traffic Service / Avancerad Trafiktjänst

Löfås, Peter January 2005 (has links)
More and more travellers use navigation-aid software to find the way while driving. Most of todays systems use static maps with little or no information at all about currently yeilding roads conditions and disturbances in the network. It is desirable for such services in the future to include information about road works, accidents, surface conditions and other types of events that affects what route is currently the best. It is also desirable to notify users about changes in the prerequisites of the chosen route after they have started their trip. This thesis investigates methods to include dynamic traffic information in route calculations and notifying users when the characteristics change for their chosen route. The thesis utilizes dynamic traffic information from The Swedish Road Agencys (Vägverket) central database for traffic information, TRISS and calculates affected clients with help of positioning through the GSM network.
26

Integrated Model of the Urban Continuum with Dynamic Time-dependent Activity-Travel Microsimulation: Framework, Prototype, and Implementation

January 2012 (has links)
abstract: The development of microsimulation approaches to urban systems modeling has occurred largely in three parallel streams of research, namely, land use, travel demand and traffic assignment. However, there are important dependencies and inter-relationships between the model systems which need to be accounted to accurately and comprehensively model the urban system. Location choices affect household activity-travel behavior, household activity-travel behavior affects network level of service (performance), and network level of service, in turn, affects land use and activity-travel behavior. The development of conceptual designs and operational frameworks that represent such complex inter-relationships in a consistent fashion across behavioral units, geographical entities, and temporal scales has proven to be a formidable challenge. In this research, an integrated microsimulation modeling framework called SimTRAVEL (Simulator of Transport, Routes, Activities, Vehicles, Emissions, and Land) that integrates the component model systems in a behaviorally consistent fashion, is presented. The model system is designed such that the activity-travel behavior model and the dynamic traffic assignment model are able to communicate with one another along continuous time with a view to simulate emergent activity-travel patterns in response to dynamically changing network conditions. The dissertation describes the operational framework, presents the modeling methodologies, and offers an extensive discussion on the advantages that such a framework may provide for analyzing the impacts of severe network disruptions on activity-travel choices. A prototype of the model system is developed and implemented for a portion of the Greater Phoenix metropolitan area in Arizona to demonstrate the capabilities of the model system. / Dissertation/Thesis / Ph.D. Civil and Environmental Engineering 2012
27

Avaliação de indicadores de desempenho na análise de importância de segmentos de uma rede viária

Dalosto, Francisco Marchet January 2018 (has links)
A identificação dos segmentos críticos da rede viária é um conhecimento básico que todo planejador de transportes deve ter sobre a rede viária. É inevitável a ocorrência de incidentes e eventos de redução da capacidade nos elementos da rede. O efeito de acidentes e obstruções em segmentos críticos da rede ocasionam impactos que prejudicam o desempenho da rede. Este estudo foi desenvolvido com o apoio do modelo de alocação de tráfego do software VISUM (versão 2015) e propõe um método para determinar a importância de cada segmento da rede viária, a identificação de segmentos críticos da rede e a avaliação de sua obstrução de forma estática e dinâmica. Para isso, são utilizados diversos indicadores de desempenho da rede viária. O método foi aplicado na região do Litoral Norte do Rio Grande do Sul, utilizando os dados de tráfego fornecidos pela CONCEPA TRIUNFO, DAER e DNIT. A determinação da importância de cada segmento decorreu da avaliação do impacto na rede causado pela obstrução do próprio segmento. Através do método proposto neste estudo foi possível identificar o segmento crítico da rede viária estudada e, de forma qualitativa, verificar a extensão da obstrução desse segmento nas análises estática e dinâmica Verificou-se que o indicador diferença do total de tempo despendido na rede é o indicador que mais apresenta crescimento com o incremento da demanda, não apresenta alterações de priorização dos segmentos frente a variações de intensidade e sentido da demanda. Os resultados deste estudo mostraram que o segmento crítico da rede pertence a BR-101 entre os municípios de Osório e Terra de Areia. O método de hierarquização proposto independe do sentido e da intensidade da demanda, e está sujeito a mais de uma métrica para avaliar o segmento crítico. Estes resultados podem subsidiar o planejamento de transportes, identificando trechos críticos da rede viária que necessitam de mais atenção dos gestores e apontando medidas de operação no caso de eventos disruptivos nos trechos críticos. / Identifying the most important link of the network is essential knowledge that the transport planners should have over the network. Incidents and events of capacity reduction in network elements are inevitable. The effect of accidents and obstructions on critical network links causes impacts that hamper network performance. This study was developed with support of VISUM (version 2015) traffic assignment model software with proposes a method to determinate each network link importance level, to identify the critical link and to measure the critical link blockage impact on network. For this, several road network performance indicators are used. The method was applied in the North Coast region of Rio Grande do Sul, using traffic data provided by CONCEPA TRIUNFO, DAER and DNIT. The link level importance in define from the own link impact due its obstruction. The proposed method identified the most critical link of the studied network and verified the qualitative impact of its obstruction extent in the static and dynamic assignment analyses It was verified that the measure total spent time difference in the network is the most sensible measure that growth with a demand increase, this measure does not present changes the link importance rank against variations of intensity and direction of demand flow changes. The results of this study show that the critical link of the network belongs to the BR-101 highway between the municipalities of Osório and Terra de Areia. The proposed hierarchical method developed with several metrics measures fond the critical link in an independent demand direction and intensity analysis. The findings may support transport planners to identify the most critical arc of a network. To better implement resources of road management and repairs. Also identify where the operation measures may be implanted in face a disruptive event on a critical link.
28

Avaliação de indicadores de desempenho na análise de importância de segmentos de uma rede viária

Dalosto, Francisco Marchet January 2018 (has links)
A identificação dos segmentos críticos da rede viária é um conhecimento básico que todo planejador de transportes deve ter sobre a rede viária. É inevitável a ocorrência de incidentes e eventos de redução da capacidade nos elementos da rede. O efeito de acidentes e obstruções em segmentos críticos da rede ocasionam impactos que prejudicam o desempenho da rede. Este estudo foi desenvolvido com o apoio do modelo de alocação de tráfego do software VISUM (versão 2015) e propõe um método para determinar a importância de cada segmento da rede viária, a identificação de segmentos críticos da rede e a avaliação de sua obstrução de forma estática e dinâmica. Para isso, são utilizados diversos indicadores de desempenho da rede viária. O método foi aplicado na região do Litoral Norte do Rio Grande do Sul, utilizando os dados de tráfego fornecidos pela CONCEPA TRIUNFO, DAER e DNIT. A determinação da importância de cada segmento decorreu da avaliação do impacto na rede causado pela obstrução do próprio segmento. Através do método proposto neste estudo foi possível identificar o segmento crítico da rede viária estudada e, de forma qualitativa, verificar a extensão da obstrução desse segmento nas análises estática e dinâmica Verificou-se que o indicador diferença do total de tempo despendido na rede é o indicador que mais apresenta crescimento com o incremento da demanda, não apresenta alterações de priorização dos segmentos frente a variações de intensidade e sentido da demanda. Os resultados deste estudo mostraram que o segmento crítico da rede pertence a BR-101 entre os municípios de Osório e Terra de Areia. O método de hierarquização proposto independe do sentido e da intensidade da demanda, e está sujeito a mais de uma métrica para avaliar o segmento crítico. Estes resultados podem subsidiar o planejamento de transportes, identificando trechos críticos da rede viária que necessitam de mais atenção dos gestores e apontando medidas de operação no caso de eventos disruptivos nos trechos críticos. / Identifying the most important link of the network is essential knowledge that the transport planners should have over the network. Incidents and events of capacity reduction in network elements are inevitable. The effect of accidents and obstructions on critical network links causes impacts that hamper network performance. This study was developed with support of VISUM (version 2015) traffic assignment model software with proposes a method to determinate each network link importance level, to identify the critical link and to measure the critical link blockage impact on network. For this, several road network performance indicators are used. The method was applied in the North Coast region of Rio Grande do Sul, using traffic data provided by CONCEPA TRIUNFO, DAER and DNIT. The link level importance in define from the own link impact due its obstruction. The proposed method identified the most critical link of the studied network and verified the qualitative impact of its obstruction extent in the static and dynamic assignment analyses It was verified that the measure total spent time difference in the network is the most sensible measure that growth with a demand increase, this measure does not present changes the link importance rank against variations of intensity and direction of demand flow changes. The results of this study show that the critical link of the network belongs to the BR-101 highway between the municipalities of Osório and Terra de Areia. The proposed hierarchical method developed with several metrics measures fond the critical link in an independent demand direction and intensity analysis. The findings may support transport planners to identify the most critical arc of a network. To better implement resources of road management and repairs. Also identify where the operation measures may be implanted in face a disruptive event on a critical link.
29

Multi-Resolution Modeling of Managed Lanes with Consideration of Autonomous/Connected Vehicles

Fakharian Qom, Somaye 29 June 2016 (has links)
Advanced modeling tools and methods are essential components for the analyses of congested conditions and advanced Intelligent Transportation Systems (ITS) strategies such as Managed Lanes (ML). A number of tools with different analysis resolution levels have been used to assess these strategies. These tools can be classified as sketch planning, macroscopic simulation, mesoscopic simulation, microscopic simulation, static traffic assignment, and dynamic traffic assignment tools. Due to the complexity of the managed lane modeling process, this dissertation investigated a Multi-Resolution Modeling (MRM) approach that combines a number of these tools for more efficient and accurate assessment of ML deployments. This study clearly demonstrated the differences in the accuracy of the results produced by the traffic flow models incorporated into different tools when compared with real-world measurements. This difference in the accuracy highlighted the importance of the selection of the appropriate analysis levels and tools that can better estimate ML and General Purpose Lanes (GPL) performance. The results also showed the importance of calibrating traffic flow model parameters, demand matrices, and assignment parameters based on real-world measurements to ensure accurate forecasts of real-world traffic conditions. In addition, the results indicated that the real-world utilization of ML by travelers can be best predicated with the use of dynamic traffic assignment modeling that incorporates travel time, toll, and travel time reliability of alternative paths in the assignment objective function. The replication of the specific dynamic pricing algorithm used in the real-world in the modeling process was also found to provide the better forecast of ML utilization. With regards to Connected Vehicle (CV) operations on ML, this study demonstrated the benefits of using results from tools with different modeling resolution to support each other’s analyses. In general, the results showed that providing toll incentives for Cooperative Adaptive Cruise Control (CACC)-equipped vehicles to use ML is not beneficial at lower market penetrations of CACC due to the small increase in capacity with these market penetrations. However, such incentives were found to be beneficial at higher market penetrations, particularly with higher demand levels.
30

An Improved Framework for Dynamic Origin-Destination (O-D) Matrix Estimation

Chi, Hongbo 09 November 2010 (has links)
This dissertation aims to improve the performance of existing assignment-based dynamic origin-destination (O-D) matrix estimation models to successfully apply Intelligent Transportation Systems (ITS) strategies for the purposes of traffic congestion relief and dynamic traffic assignment (DTA) in transportation network modeling. The methodology framework has two advantages over the existing assignment-based dynamic O-D matrix estimation models. First, it combines an initial O-D estimation model into the estimation process to provide a high confidence level of initial input for the dynamic O-D estimation model, which has the potential to improve the final estimation results and reduce the associated computation time. Second, the proposed methodology framework can automatically convert traffic volume deviation to traffic density deviation in the objective function under congested traffic conditions. Traffic density is a better indicator for traffic demand than traffic volume under congested traffic condition, thus the conversion can contribute to improving the estimation performance. The proposed method indicates a better performance than a typical assignment-based estimation model (Zhou et al., 2003) in several case studies. In the case study for I-95 in Miami-Dade County, Florida, the proposed method produces a good result in seven iterations, with a root mean square percentage error (RMSPE) of 0.010 for traffic volume and a RMSPE of 0.283 for speed. In contrast, Zhou’s model requires 50 iterations to obtain a RMSPE of 0.023 for volume and a RMSPE of 0.285 for speed. In the case study for Jacksonville, Florida, the proposed method reaches a convergent solution in 16 iterations with a RMSPE of 0.045 for volume and a RMSPE of 0.110 for speed, while Zhou’s model needs 10 iterations to obtain the best solution, with a RMSPE of 0.168 for volume and a RMSPE of 0.179 for speed. The successful application of the proposed methodology framework to real road networks demonstrates its ability to provide results both with satisfactory accuracy and within a reasonable time, thus establishing its potential usefulness to support dynamic traffic assignment modeling, ITS systems, and other strategies.

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