Techn. University, Diss., 2004--Darmstadt. / Dateien im PDF-Format.

Techn. University, Diss., 2005--Berlin.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 171-182).

by Pierre Dersin, Stanley B. Gershwin, Michael Athans. / Includes bibliographical references. / "July, 1976." / Sponsored by the Department of Transportation. DOT/TSC/849

Bibliography: p. 82-83. / Issued also as a M.S. thesis in the Dept. of Electrical Engineering, 1968. / DSR Project no. 79723.

Thesis (MTech (Civil Engineering))--Cape Peninsula University of Technology, 2008. / There is an ever increasing need to introduce travel demand measures as the ability to construct new and upgrade existing roads to accommodate additional traffic volumes decreases. The City of Cape Town, hereinafter referred to as the City, has forecasted that traffic in the city could continue to increase by two and a half percent per year. To mitigate against the increased traffic volumes, the City is proposing a number of travel demand strategies, including a park and-ride facilities and high occupancy vehicle initiatives in the short term. The City’s draft travel demand management strategy identifies congestion charging as a measure more possible implementation in the medium term. This study investigates the feasibility of introducing a congestion charge from a traffic engineering perspective. This entails determining if there could be a reduction in traffic entering the Central Business District, what type of congestion charge is most suited for Cape Town and what type of technology is most appropriate at this point in time. In determining the type of charge and technology for introduction in Cape Town, international experience and trials were drawn upon in terms of case studies and research completed. These included developed and developing cities that had either introduced a congestion charge or considered it. To determine the potential level of traffic reduction, transportation elasticities for road pricing/congestion charging were used. This method of calculating the traffic reduction has been used on similar studies and provides a reasonable indication of the potential percentage reduction which could be achieved. The elasticities were based on post-implementation studies undertaken in cities which had introduced a congestion charge or road user pricing. For this study, elasticities between -0.1 and -0.5 were used. The study found that of the types of congestion charging available, a simple cordon charge, around the central business district (CBD) was most feasible. A cordon area would be more appropriate due to the small charge area involved, the flexibility that it allows and because it does not need to be visually intrusive in terms of roadside and enforcement equipment. The location of the cordon area also allows the key roads around the CBD to become the bypass route for vehicles that currently pass through the area. In terms of the charge payment system, it was found that presently, a manual payment system would be more appropriate for the city than a tag and beacon system.

Este trabalho apresenta uma comparação e avaliação das arquiteturas de roteamento IP e IP sobre MPLS. Inicialmente, são apresentados alguns conceitos básicos dos protocolos IP e MPLS, e suas relações com a camada 2 do modelo OSI. Duas características foram analisadas: o processo de encaminhamento e as granularidades para engenharia de tráfego. A medição de desempenho foi feita com computadores Linux realizando a tarefa de roteamento/encaminhamento de datagramas IP em diferentes tipos de redes Ethernet. Com base nos resultados dos testes, é feita uma discussão sobre o desempenho e topologias adequadas para cada arquitetura. / This work presents a comparison and evaluation of IP and the IP over MPLS routing architectures. Initially, some basic concepts of IP and MPLS protocols and their relationship with layer 2 of OSI model are introduced. Two characteristics were analyzed: the forwarding process and traffic engineering granularity. The performance analysis was realized on Linux computers routing/forwarding IP datagramas at different types of Ethernet networks. Considering the results of the tests, a discussion about performance and suitable topologies is made for each architecture.

O objetivo deste trabalho é o desenvolvimento e proposição de modelos matemáticos que possam estimar, com a precisão necessária para efeitos de aplicação prática, o grau ou o nível de segurança de interseções, semaforizadas ou não, usando-se o conceito de oportunidades de conflito de tráfego. O conceito de oportunidade de conflito de tráfego tem sido proposto para obter medidas analíticas de segurança, sendo uma medida correlata de segurança que pode substituir com vantagem as medidas usuais como histórico de acidentes e conflitos de tráfego. Os modelos que usam o conceito de oportunidades de conflito de tráfego necessitam apenas de dados operacionais das interseções, o que torna este parâmetro uma medida potencialmente útil para aplicações práticas na determinação do nível de segurança de um determinado local ou fazer projeções sobre a efetividade de projetos de segurança. São apresentados e discutidos trabalhos de outros autores sobre o assunto, baseados nos quais foram desenvolvidas alternativas às propostas por eles formuladas. Foram analisados pontos não tratados como a aplicação do conceito de oportunidade de conflito de tráfego no período de entreverdes, bem como o estudo de pedestres nas diferentes situações de travessia (nos estudos revisados, somente foi encontrada a análise de travessia de pedestres diante do movimento de conversão à esquerda com fluxo oposto). Foi realizado um estudo piloto numa interseção real com o objetivo de testar metodologias de trabalho de campo, o que permitiu estruturar um trabalho de validação de campo por meio de diagnósticos qualitativos. / The purpose of this work is, through the use of mathematic models, to estimate the level of risk using the concept of traffic conflict opportunity at signalized and unsignalized intersections. The concept of traffic conflict opportunity has been proposed to measure the level of risk, and it is considered as an alternative measure of traffic safety, potentially more useful than the traditional safety measures like traffic accident data or traffic conflict technique. The traffic conflict opportunity models do not require complex field data, only the operational data of the intersection as traffic counts and control parameters are needed. This work presents and analyses other authors studies about this subject, based on which were proposed alternative methods for their formulations. Points such as the safety analysis of the intergreen period using traffic conflict opportunity, not found in those studies, were treated in this work, as well as the pedestrian crossing risk in various situations (in the revised studies, only the analysis of pedestrian crossing risk due to a left turn movement facing an opposing flow was found). In order to test methodologies and to collect field data, it was performed a pilot study at a real intersection. The pilot study allowed to define the goals and the means needed to carry out a field validation by qualitative diagnostic analysis.

As curvas horizontais das rodovias notoriamente colecionam acidentes de trânsito, nos quais geralmente os automóveis derrapam e escapam pela tangente, enquanto que os veículos pesados costumam tombar lateralmente. Os critérios consagrados de projeto geométrico das curvas, consideradas planas, ignoram a propensão dos veículos pesados ao tombamento lateral, confiando apenas nas forças de atrito lateral e na superelevação transversal da via para a manutenção do veículo em trajetória segura. O presente trabalho pretende desenvolver modelo de projeto que forneça margens de segurança tanto contra o escorregamento e o tombamento lateral de veículos pesados (semi-reboques) em curvas horizontais com greide descendente. O modelo proposto no presente estudo é sensível a fatores de segurança intrínsecos e extrínsecos aos veículos, incluindo características geométricas longitudinais e transversais da pista, e a variação da trajetória do veículo dentro da curva. Os resultados obtidos demonstram que os critérios de projeto atuais não garantem a segurança de semi-reboques em curvas descendentes de raio mínimo, principalmente nas curvas de menor velocidade. O critério desenvolvido permite o estabelecimento de margens de segurança para a regulamentação de velocidade em curvas horizontais descendentes já existentes, bem como possibilita a determinação da velocidade de projeto segura para curvas descendentes em novas vias. / The grade effect on highway horizontal curves is notorious for traffic accidents because automobiles tend to skid and leave the road whereas commercial loaded vehicles tend to roll over. The standard criteria for the geometric design of these curves, which are considered flat, ignore the heavy vehicles propensity for rollover by relying solely on the forces of lateral friction and on the road superelevation in order to keep the vehicle in a safe trajectory. The current study has been set out in order to develop a model that will yield margins of safety to prevent skidding and rollover of heavy vehicles (semi-trailers) on horizontal descending highway curves. The model proposed in the present study is sensitive to safety variables both intrinsic and extrinsic to the vehicles, including longitudinal and transversal characteristics of the road, and vehicles trajectory variations at horizontal curves. The results of the study show that the currently adopted safety guidelines do not guarantee the safety of such articulated vehicles on grade curves with minimum radii, mostly at lower speeds curves. As a result, the proposed criteria allows the establishment of margins of safety that can be applied to regulatory speed signs on existing horizontal descending curves, and for the setting of safe design speeds for descending curves on new highways.

CoordenaÃÃo de AperfeiÃoamento de NÃvel Superior / A utilizaÃÃo de mecanismos que auxiliem a tomada de decisÃo à cada vem mais difundida no meio tÃcnico, o uso destes ferramentais por Engenheiros de TrÃfego auxiliam na anÃlise do desempenho de novos cenÃrios urbanos, definiÃÃo de novas estratÃgias de coordenaÃÃo, isolamento de semÃforos, dentre outros, de forma a contribuir para a eficÃcia do sistema de trÃnsito. Com o aumento da problemÃtica relacionada ao trÃnsito nas grandes cidades, a implantaÃÃo de semÃforos surge como uma das medidas mitigadoras. Devido à existÃncia de vÃrios mÃtodos de implantaÃÃo de semÃforos, nacionais e estrangeiras, conforme as caracterÃsticas das cidades que os originaram, à necessÃrio alÃm da identificaÃÃo dos locais onde se devem implantar os semÃforos, utilizar outros mÃtodos, a exemplo de um otimizador e um simulador de trÃfego, que atravÃs de medidas de desempenho, auxiliem à anÃlise dos impactos operacionais no trÃnsito, de forma a verificar quais as reais melhorias resultantes das implantaÃÃes, considerando outras realidades. Este trabalho terà como estudo de caso um trecho viÃrio da Ãrea central da cidade de Fortaleza-Ce. Na concepÃÃo deste estudo, foram definidas as seguintes etapas: aplicaÃÃo das metodologias de implantaÃÃo de semÃforos estudadas, definiÃÃo do modo de operaÃÃo e coordenaÃÃo e avaliaÃÃo operacional. Optou-se por utilizar o simulador de trÃfego Integration que atravÃs de suas medidas de desempenho auxiliou na definiÃÃo do cenÃrio que apresentou os maiores ganhos operacionais em relaÃÃo ao cenÃrio atual. / Decision making techniques have become increasingly widespread in the technical field. The use of such tools by Traffic Engineers assists in analyzing the performance of new urban settings, the definition of new coordination strategies, traffic signal isolation, among others, as to contribute to the effectiveness of the traffic control system. With increasing problems related to traffic in large cities, the implementation of traffic control signals emerges as one of the mitigating measures. As there are several national and international methods used in the implementation of traffic signals, depending on the characteristics of the cities in which they originate, it is necessary not only to identify the sites where traffic signals should be installed, but also to utilize different methods. Such methods include traffic signal optimization and simulation tools, which assist in the analysis of operational impacts through performance measures, indentifying which are the real improvements resulting from the implementations, considering other realities. The present work will study a road section from the central area of the city of Fortaleza, in the state of CearÃ, Brazil. The following stages were defined: application of the studied methodologies of traffic control signal implementation, mode of operation, and operational coordination and evaluation. The traffic simulator Integration was used, and through its performance measurements it was possible to define the setting that exhibited the highest operational gains in relation to the current setting.