EVALUATION OF NATURAL AND TRAFFIC-PRODUCING TURBULENCES USING FULL SCALE DATA FROM FOUR STREET CANYONS

In urban areas, high air pollutant concentrations may be observed, mostly within street canyons, where buildings and other obstacles disturb the airflow and turbulence. Air motions inside the street canyons are influenced by aerodynamic and thermal effects and by the movements of the vehicles. Parameters related with natural and traffic produced turbulences are estimated for four street canyons considering all wind directions. Available data used include air pollution concentrations measured in Göttinger Strasse (Hannover, Germany), Schildhornstrasse (Berlin, Germany), Jagtvej (Copenhagen, Denmark) and Hornsgatan (Stockholm, Sweden), and background pollution, wind speed and direction measured on the roof of a nearby building and information of traffic flow. For each street canyon, the variation with traffic density of critical wind speed (that equals the contributions of turbulent motions related to wind and traffic to the effective velocity variance inside the street canyon) is also studied

Study of natural and traffic-producing turbulences analysing full-scale data from four street canyons

Parameters related with natural and traffic producing turbulences are estimated for four street canyons considering all wind directions. Available data include air pollution concentrations measured in Göttinger Strasse (Hannover, Germany), Schildhornstrasse (Berlin, Germany), Jagtvej (Copenhagen, Denmark) and Hornsgatan (Stockholm, Sweden), background pollution, wind speed and direction measured on the roof of a nearby building and information of traffic flow. Results show that coefficients a and b, related to natural- and traffic- produced turbulences, vary with wind direction. The variation of critical wind speed with traffic density and wind direction is also studied for each street canyon.Fil: Mazzeo, Nicolas Antonio. Universidad Tecnológica Nacional. Facultad Regional Avellaneda; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Venegas, Laura Esperanza. Universidad Tecnológica Nacional. Facultad Regional Avellaneda; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

EVALUATION OF NATURAL AND TRAFFIC-PRODUCING TURBULENCES USING FULL SCALE DATA FROM FOUR STREET CANYONS

In urban areas, high air pollutant concentrations may be observed, mostly within street canyons, where buildings and other obstacles disturb the airflow and turbulence. Air motions inside the street canyons are influenced by aerodynamic and thermal effects and by the movements of the vehicles. Parameters related with natural and traffic produced turbulences are estimated for four street canyons considering all wind directions. Available data used include air pollution concentrations measured in Göttinger Strasse (Hannover, Germany), Schildhornstrasse (Berlin, Germany), Jagtvej (Copenhagen, Denmark) and Hornsgatan (Stockholm, Sweden), and background pollution, wind speed and direction measured on the roof of a nearby building and information of traffic flow. For each street canyon, the variation with traffic density of critical wind speed (that equals the contributions of turbulent motions related to wind and traffic to the effective velocity variance inside the street canyon) is also studied

Modelling traffic flow emissions at signalized intersection with PTV vissim

The effect of roadway intersection design is strictly linked to a reduction in traffic congestion, fuel consumption and emissions in an urban area. This paper presents a comparative result of the typical four-legged intersection and roundabout operational performance for effective management. Accordingly, a computer model for estimation traffic emissions for two kinds of intersections is created. This study presents a detailed analysis and modelling traffic flow emissions using PTV vissim software and methodology with reasonable solutions to plan a road intersection

Avaliação da qualidade do ar no município de Leiria

Mestrado em Engenharia do AmbienteA constante evolução da sociedade actual e o seu desenvolvimento desenfreado põem de parte, muitas vezes, os impactos em termos de qualidade ambiental que daí advêm. No sentido de controlar a qualidade do ar, é importante proceder à sua avaliação através do recurso a modelos que permitem analisar as concentrações dos poluentes na atmosfera, a contribuição das diversas fontes e influência de determinadas condições, sejam elas topográficas, meteorológicas ou outras. O objectivo principal do presente trabalho é avaliar a qualidade do ar no município de Leira, através da aplicação de um de modelo da qualidade do ar. Para a realização deste estudo efectuou-se uma pesquisa acerca dos modelos de qualidade do ar em termos de funcionalidades, bem como as vantagens e limitações da sua aplicação em diferentes condições e para diferentes objectivos. Foi seleccionado o modelo ADMS que se baseia no modelo gaussiano, e inclui também o módulo químico e de street-canyon. Procedeu-se à caracterização da área de estudo, à análise das emissões de tráfego obtidas a partir do modelo TREM, assim como dos dados meteorológicos fornecidos pelo modelo MM5, respeitantes ao dia 21 de Setembro de 2007, dia alvo do estudo. O modelo foi aplicado para analisar a variação espacial e temporal dos poluentes SO2, CO, NOx, COV e PM10. Os resultados obtidos foram validados através da comparação com medições de concentração de poluentes efectuadas num ponto localizado dentro da área de estudo para o dia seleccionado. De uma maneira geral, os resultados da modelação demonstram boa concordância com os valores medidos. ABSTRACT: The constant evolution of our society and its wild development, do not consider its impacts in the quality of the environment. In order to control air quality, it is important to proceed to its evaluation, using models that allow analyzing the concentration of the pollutants emitted into the atmosphere, the contribution of the sources and the influence of certain conditions, whether topographical, meteorological or other. The main objective of this work, intends to evaluate the quality of the air in the city of Leiria, trough the application of a model of air quality. To accomplish of this study, a review of air quality models in terms of functionalities, as well as the advantages and limitations of its application in different conditions and for different purposes, have been performed. The model ADMS is based on the gaussian model, that also includes the chemical and of streetcanyon modules. It was proceeded the characterization of the study area, to the analysis of the traffic emissions obtained by TREM model, as well as the meteorological data supplied by the MM5 model, concerning the 21 September of 2007, the study target day. The model was applied to analyze the space distribution and temporal variation of pollutants SO2, CO, NOx, COV and PM10. The results were validated through the comparison with measurements of pollutants concentration, performed in a point located inside of the study area for the selected day. In general way, the modeling results shows a good agreement with the measured value

Sistemas inteligentes de transportes - impacte nos consumos e emissões

Mestrado em Engenharia MecânicaUma forma de otimizar a escolha de rotas consiste no recurso aos Sistemas Inteligentes de Transportes (ITS). Estes sistemas possibilitam aos condutores identificar previamente problemas na rede e possíveis soluções em rotas alternativas. A análise destas alternativas para um determinado par origem/destino baseada nestes sistemas afigura-se relevante, para que o utilizador possa escolher a rota que esteja associada a um menor nível de congestionamento, consumos e emissões. A presente Dissertação pretende avaliar o impacte destes sistemas ao nível das emissões de poluentes numa zona urbana durante o período da hora de ponta. Para isso, foi efetuada a microsimulação de tráfego e emissões para uma situação de referência seguida de avaliação dos consumos e emissões decorrente da utilização de ITS num conjunto de cenários de incidentes de tráfego em diferentes vias de acesso a um centro urbano de média dimensão. O impacte será avaliado para diferentes vias de tráfego (urbana, suburbana ou autoestrada) e para todo o domínio urbano em análise (rede modelada composta pelas principais vias do centro da cidade de Aveiro). Na fase inicial deste trabalho foram recolhidos no terreno dados relativos a fluxos de tráfego, sinalização rodoviária e características das vias em estudo em pontos-chave do domínio. Posteriormente efetuou-se a modelação da rede viária com a aplicação do modelo de tráfego VISSIM, e estimaram-se as emissões totais de NOx, HC, CO e CO2 de emissões atmosféricas recorrendo à metodologia de cálculo Vehicle Specific Power (VSP), a qual demonstrou simular valores dentro dos limites de confiança dos valores observados. O estudo desenvolvido confirma que os ITS são uma mais-valia na redução dos tempos de viagem dos condutores que circulam na via onde ocorre um incidente. Nesta via quando aplicado o ITS, registam-se reduções das emissões entre os 45% e os 95%. Já no caso de não se aplicar ITS os aumentos na via no incidente chegam a atingir os 570% no caso do poluente CO. As rotas alternativas permitem poupanças em tempos de viagem que em alguns casos superam os 50%. No entanto, não deixa de ser uma realidade o aumento de emissões face ao cenário de referência (sem incidentes), sempre que acontece um incidente. Em todos os cenários a melhor rota alternativa é a que compreende trajetos mistos (urbano e não urbano) mesmo quando se verifica um grande número de veículos em circulação. Também para todo o domínio sem ITS, tendo como referência a situação sem incidentes, a ocorrência de incidentes aumenta todos os poluentes com destaque para o CO que apresenta, em todos os cenários, os maiores aumentos. Nos casos estudados na presente Dissertação verifica-se que a ocorrência de um incidente que obrigue a fechar uma via rodoviária, é prejudicial ao nível das emissões nas alternativas sugeridas.One way to optimize route choice is using the Intelligent Transportation Systems (ITS). These systems enable drivers to previously identify possible network problems and solutions in alternative routes. The analysis of these alternatives for an origin / destination pair based on these systems it is important for the user to choose the route that is associated with a lower level of congestion, fuel consumption and emissions. This thesis aims to assess the impact of these systems to the level of pollutant emissions in an urban area during the rush hour. Microscopic traffic and emissions modeling was performed for a baseline situation followed fuel consumption and emissions from the use of ITS in a set of scenarios of traffic incidents in different access routes to a medium-sized urban center. The impact will be assessed for different traffic routes (urban, suburban or freeway) and the entire urban area under consideration (city of Aveiro). In the initial phase of this study field data on traffic flows, road signs and characteristics of the routes under study were collected at key points of the domain. Subsequently road network modeling with application of VISSIM traffic model was performed, and the total NOx, HC, CO and CO2 emissions were estimated using the calculation methodology Vehicle Specific Power (VSP), which showed values within the confidence limits of the observed values. The study confirms that the ITS are an advantage in reducing travel times for drivers moving towards where an incident occurs. At intersections where the incidents occur, there are emissions reductions between 45% and 95% when ITS are used. In the case of not applying ITS, CO increases up to 570%. The alternative routes allow savings in journey times which in some cases exceed 50%. However, it is still a reality the increase in emissions compared to the baseline scenario (without incidents), whenever an incident happens. In all scenarios the best alternative route is a mixed path (urban and nonurban) even when there are a large number of vehicles. Also for the entire domain without ITS, with reference to the situation without incident, the occurrence of incidents increases all pollutants especially CO that presents, in all scenarios, the largest increase. In the cases studied in this thesis the occurrence of an incident requiring a closed road, is detrimental to emissions level in the suggested alternatives

Development of a Decision Support Framework for the Planning of Sustainable Transportation Systems

With the rapid increase in economic development throughout the world, there is stress on the resources used to support global economy, including petroleum, coal, silver, and water. Currently, the world is consuming energy at an unprecedented rate never seen before. The finite nature of such non-renewable natural resources as petroleum and coal puts pressure on the environmental system, and ultimately reduces the availability of resources for future generations. Hence, it is critical to develop planning and operational strategies that seek to achieve a sustainable use of existing natural resources. With this motivation, this dissertation focuses to develop a decision support framework based on multiple performance measures for the planning of sustainable transportation systems. A holistic approach was adopted to compute performance indices for a System of Systems (SOS) including the Transportation, Activity, and Environmental systems. The performance indices were synthesized to calculate a composite sustainability index to evaluate the sustainability of the overall SOS. To help make better design and policy decisions at an aggregate level, a suitable modeling approach that captures the dynamic interactions within the SOS was formulated. A method of system of ordinary differential equations was chosen to model the aggregated performance indices and their interdependencies over time. In addition, systems and control methodology was used in the development of optimal policies (with respect to investments in various systems) for decision making purposes. The results indicated that the Transportation and Activity system both follow positive trend over the years whereas the Environmental system follows an overall negative trend. This is evident as continuous increase in growth and transportation will result in decreased performance of Environmental system over time. The results also highlighted periodic behavior with a phase lag for the performance of Transportation and the Activity system; the performance of Environment system decayed with time. In addition, the results demonstrated that it is possible to formulate an optimal control to predict investment decisions over time. Furthermore, the results from this research provided an alternate, cost-effective method to rank and prioritize projects based on sustainability index values. The major contributions of this research are fourfold. The first contribution of this research is the development of a framework to generate sustainability indices for policy making considering, explicitly, multiple interdependent systems. This research is first of its kind to study the dynamical interactions between the three systems: Transportation, Activity, and Environment. The second contribution of this research is a detailed analysis to understand the dynamics of the three interdependent systems. Multiple insights were obtained from this research. The techniques learnt can be applied to perform multi-city network modeling through the concept of interconnected networks. In addition, the need to conserve the environment and preserve the resources is highlighted. The third contribution of this research work is development of control mechanisms to evaluate investment policies for the design of sustainable systems. Investment decisions were derived from the design. The fourth contribution of this research is the development of a framework to estimate sustainability indices for the evaluation and prioritization of transportation projects. Projects are prioritized and ranked based on the sustainability index values. The greater the sustainability index value, the higher is the project priority. This provides a comprehensive mechanism to incorporate information beyond traditional techniques

Plataforma de informação de tráfego para redução de consumos e emissões

Doutoramento em Engenharia MecânicaApesar das recentes inovações tecnológicas, o setor dos transportes continua a exercer impactes significativos sobre a economia e o ambiente. Com efeito, o sucesso na redução das emissões neste setor tem sido inferior ao desejável. Isto deve-se a diferentes fatores como a dispersão urbana e a existência de diversos obstáculos à penetração no mercado de tecnologias mais limpas. Consequentemente, a estratégia “Europa 2020” evidencia a necessidade de melhorar a eficiência no uso das atuais infraestruturas rodoviárias. Neste contexto, surge como principal objetivo deste trabalho, a melhoria da compreensão de como uma escolha de rota adequada pode contribuir para a redução de emissões sob diferentes circunstâncias espaciais e temporais. Simultaneamente, pretende-se avaliar diferentes estratégias de gestão de tráfego, nomeadamente o seu potencial ao nível do desempenho e da eficiência energética e ambiental. A integração de métodos empíricos e analíticos para avaliação do impacto de diferentes estratégias de otimização de tráfego nas emissões de CO2 e de poluentes locais constitui uma das principais contribuições deste trabalho. Esta tese divide-se em duas componentes principais. A primeira, predominantemente empírica, baseou-se na utilização de veículos equipados com um dispositivo GPS data logger para recolha de dados de dinâmica de circulação necessários ao cálculo de emissões. Foram percorridos aproximadamente 13200 km em várias rotas com escalas e características distintas: área urbana (Aveiro), área metropolitana (Hampton Roads, VA) e um corredor interurbano (Porto-Aveiro). A segunda parte, predominantemente analítica, baseou-se na aplicação de uma plataforma integrada de simulação de tráfego e emissões. Com base nesta plataforma, foram desenvolvidas funções de desempenho associadas a vários segmentos das redes estudadas, que por sua vez foram aplicadas em modelos de alocação de tráfego. Os resultados de ambas as perspetivas demonstraram que o consumo de combustível e emissões podem ser significativamente minimizados através de escolhas apropriadas de rota e sistemas avançados de gestão de tráfego. Empiricamente demonstrou-se que a seleção de uma rota adequada pode contribuir para uma redução significativa de emissões. Foram identificadas reduções potenciais de emissões de CO2 até 25% e de poluentes locais até 60%. Através da aplicação de modelos de tráfego demonstrou-se que é possível reduzir significativamente os custos ambientais relacionados com o tráfego (até 30%), através da alteração da distribuição dos fluxos ao longo de um corredor com quatro rotas alternativas. Contudo, apesar dos resultados positivos relativamente ao potencial para a redução de emissões com base em seleções de rotas adequadas, foram identificadas algumas situações de compromisso e/ou condicionantes que devem ser consideradas em futuros sistemas de eco navegação. Entre essas condicionantes importa salientar que: i) a minimização de diferentes poluentes pode implicar diferentes estratégias de navegação, ii) a minimização da emissão de poluentes, frequentemente envolve a escolha de rotas urbanas (em áreas densamente povoadas), iii) para níveis mais elevados de penetração de dispositivos de eco-navegação, os impactos ambientais em todo o sistema podem ser maiores do que se os condutores fossem orientados por dispositivos tradicionais focados na minimização do tempo de viagem. Com este trabalho demonstrou-se que as estratégias de gestão de tráfego com o intuito da minimização das emissões de CO2 são compatíveis com a minimização do tempo de viagem. Por outro lado, a minimização de poluentes locais pode levar a um aumento considerável do tempo de viagem. No entanto, dada a tendência de redução nos fatores de emissão dos poluentes locais, é expectável que estes objetivos contraditórios tendam a ser minimizados a médio prazo. Afigura-se um elevado potencial de aplicação da metodologia desenvolvida, seja através da utilização de dispositivos móveis, sistemas de comunicação entre infraestruturas e veículos e outros sistemas avançados de gestão de tráfego.Despite recent technological innovations, transportation sector is still producing significant impacts on the economy and environment. In fact, the success in reducing transportation emissions has been lower than desirable due to several factors such as the urban sprawl and several barriers to the market penetration of cleaner technologies. Therefore, the “Europe 2020” strategy has emphasised the relevance of improving the efficiency in the transportation networks through the better use of the existing infrastructures. In this context, the main objective of this thesis is increasing the understanding of how proper route choices can contribute to reduce emissions output over different spatial and temporal contexts. Simultaneously, it is intended to evaluate the potential of different traffic management strategies in terms of traffic performance and energy/environmental efficiency. The integration of empirical and analytical methods to assess the impact of different traffic optimization strategies on CO2 emissions and local pollutants constitutes one the main contributions of this work. This thesis has been divided in two main parts. The first is predominantly empirical, using field data as the main source of information. Using GPS equipped vehicles, empirical data for approximately 13200 km of road coverage have been collected to estimate energy and emissions impacts of route choice in three different scenarios: a medium-sized urban area (Aveiro), a metropolitan area (Hampton Roads, VA) and an intercity corridor (Oporto-suburban area). The second part, predominantly analytical, is essentially based on the output of traffic simulators and optimization models. The analytical component was based on the capability of microscopic traffic models to generate detailed emissions information and to generate link-based performance functions. Then, different traffic management strategies were tested to evaluate road networks in terms of traffic performance and emissions. Both outcomes of the empirical and analytical approaches have demonstrated that fuel use and emissions impacts can also be significantly reduced through appropriate route choices and advanced traffic management systems. The empirical assessment of route choice impacts has shown that both during off peak and peak periods, the selection of an appropriate route can lead to significant emissions reduction. Depending on the location, potential emissions savings of CO2 up to 25% and local pollutants up to 60% were found. The analytical approach has demonstrated that it is possible to significantly reduce system environmental costs (30%) by modifying traffic flow distribution along a corridor with 4 alternative routes. However, despite the positive results in terms of the potential for emissions reduction based on appropriate route choices, a number of important trade-offs that need to be considered in future implementations of eco-routing systems. Among these trade-offs it is worth noting that: i) different pollutants may lead to different ecorouting strategies, ii) the minimization of pollutants emissions often involves choosing urban routes (densely populated), iii) for higher penetration levels of eco-routing devices considering local pollutants, system environmental impacts can be higher than if drivers were guided under the traditional devices focused on travel time. With this research, it has been demonstrated that road traffic management strategies focused on minimizing CO2 emissions and fuel consumption can be compatible with the minimization of system travel time. On the other hand the minimization of local pollutants may lead to considerable increases in travel time. However, given the trend rate of reduction in the emissions factors of local pollutants, it is expected that such trade-offs would tend to be minimized in medium term. Thus, the developed methodology has great potential for further real life application, either through the use of nomadic devices, infrastructures to vehicle communication or different advanced traffic management systems

Integrated Science Assessment for Oxides of Nitrogen — Health Criteria

National Ambient Air Quality Standards (NAAQS) are promulgated by the U.S. Environmental Protection Agency (EPA) to meet requirements set forth in Sections 108 and 109 of the Clean Air Act (CAA). These sections require the EPA Administrator (1) to list widespread air pollutants that reasonably may be expected to endanger public health or welfare; (2) to issue air quality criteria that assess the latest available scientific information on the nature and effects of ambient exposure to the criteria pollutants; (3) to set “primary” NAAQS to protect human health with adequate margin of safety and to set “secondary” NAAQS to protect against welfare effects (e.g., effects on vegetation, ecosystems, visibility, climate, manmade materials, etc); and (4) to periodically review and revise, as appropriate, the criteria and NAAQS for a given listed pollutant or class of pollutants. The purpose of this Integrated Science Assessment (ISA) for Oxides of Nitrogen (NOx) – Health Criteria is to critically evaluate and assess the latest scientific information published since the 1993 NOx Air Quality Criteria Document (AQCD), with the main focus on pertinent new information useful in evaluating health effects data associated with ambient air nitrogen oxides exposures. A First External Review Draft of this ISA (dated August 2007) was released for public comment and was reviewed by the Clean Air Scientific Advisory Committee (CASAC) in October 2007; a Second External Review Draft was made available to the public in March 2008. Public comments and CASAC recommendations have been taken into account in making revisions to the document for incorporation into this final ISA. This document will provide inputs to the risk and exposure analyses prepared by EPA’s Office of Air Quality Planning and Standards (OAQPS), which will lead to the proposal and, ultimately, promulgation of decisions on potential retention or revision, as appropriate, of the current Nitrogen Dioxide (NO2) NAAQS by the EPA Administrator. Preparation of this document was coordinated by staff of EPA’s National Center for Environmental Assessment in Research Triangle Park (NCEA-RTP). NCEA-RTP scientific staff, together with experts from other EPA/Office of Research and Development (ORD) laboratories and academia, contributed to writing of document chapters. Earlier drafts of document materials were reviewed by non-EPA experts in peer consultation workshops held by EPA. This ISA describes the nature, sources, distribution, measurement, and concentrations of nitrogen oxides in outdoor (ambient) and indoor environments. It also evaluates the latest data on human exposures to ambient nitrogen oxides and consequent health effects in exposed human populations, to support decision making regarding the primary (health-based) NO2 NAAQS. NCEA acknowledges the valuable contributions provided by authors, contributors, and reviewers and the diligence of its staff in the preparation of this document