Dissertations / Theses on the topic 'Traffic flow - Urban areas'
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Kothuri, Sirisha Murthy. "Exploring Pedestrian Responsive Traffic Signal Timing Strategies in Urban Areas." PDXScholar, 2014. https://pdxscholar.library.pdx.edu/open_access_etds/1934.
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The role of walking in the development of healthy, livable communities is being increasingly recognized. In urban areas, intersections represent locations where different modes converge, and are often viewed as deterrents to walking. This is due to the unwarranted and often unnecessary delays imposed by signal timing policies for pedestrians and increased potential for conflicts. Traditional signal timing design prioritizes vehicles over pedestrians leading to undesirable consequences such as large delays and risky pedestrian behaviors. Pedestrians are accommodated in a manner that is designed to cause least interruption to the flow of motor vehicles. This lack of pedestrian accommodation at signalized intersections is the focus of this dissertation.
Understanding pedestrian attitudes and perceptions is important because it offers insights into actual crossing behavior at signalized intersections. An intercept survey of 367 crossing pedestrians was undertaken at four signalized intersections in Portland, Oregon, and binary logistic regression models were constructed to quantify the impacts of demographics, trip characteristics and type of infrastructure on pedestrian perceptions and attitudes regarding delay, crossing time and motivators for crossing decisions. Safety was found to have a larger effect than compliance on the decision to cross the street. Pedestrians at recall intersections expressed higher satisfaction with delay than at actuated intersections.
Novel methods to measure pedestrian delay using 2070 signal controllers and Voyage software were developed. These methods have been adopted by the City of Portland to record actuation trends and delays at various intersections. In the absence of demand data, pedestrian push button actuations can be considered as a proxy for crossing demand. The micro-simulation software VISSIM was used to analyze delays resulting from varying pedestrian and vehicle volumes on a network of three intersections in Portland, Oregon. From a pedestrian perspective, free operation was found to be always beneficial due to lower pedestrian delays. However, from a system wide perspective, free operation was found to be beneficial only under low-medium traffic conditions from an overall delay reduction viewpoint, while coordinated operation showed benefits under heavy traffic conditions, irrespective of the volume of pedestrians. Control strategies were developed to identify the best mode of signal controller operation that produced the lowest overall average delay per user. A procedure to identify the optimal control strategy based on user inputs (major street volume to capacity ratios and rate of pedestrian phase serviced for the minor street) was developed. The procedure was applied to a network of three intersections in east Portland, OR and the findings were verified.
This research offers significant contributions in the field of pedestrian research. The findings related to attitudes and perceptions of crossing pedestrians offer greater insights into pedestrian crossing behavior and add to the body of existing literature. The methods developed to obtain pedestrian actuations and delay data from signal controllers represent an easy and cost-effective way to characterize pedestrian service at intersections. The results pertaining to signal timing strategies represent an important step towards incorporating pedestrian needs at intersections and demonstrate how control strategies employed to benefit pedestrians could benefit the entire system.
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AGOSTI, ABRAMO. "MODELS OF TURBULENCE. APPLICATIONS TO PARTICULATE MIXING INDUCED BY TRAFFIC FLOW IN URBAN AREAS." Doctoral thesis, Università degli Studi di Milano, 2013. http://hdl.handle.net/2434/217169.
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In this work we address our attention to the estimation of the contribution of non-exhaust sources, like brake abrasion, tire and road wear and resuspension of particles, to the final PM air concentration; particularly we focus our investigation on the resuspension of PM deposited on road pavement surfaces and raised by the air turbulence produced by the vehicles flux, under urban and extra-urban traffic conditions.
Our approach to the problem is based on modeling techniques. We refer to measurement data from literature to determine the selected empirical parameters contained in our models.
Analytical models based on algebraic eddy diffusivity hypothesis are applied to describe the mean statistical component of flow generated by air recirculation inside a canyon and by the far-wake structure besides moving vehicles of simplified geometrical shapes.
The analysis of the far wake solutions is suitable to the description of vehicle wakes interaction, which permits to apply our analysis to different driving cycles conditions.
Numerical simulations based on finite element discretization of suitable two-equation turbulence models are employed to describe near-wake structures, which cause the strongest mixing of atmospheric pollutants and resuspension of road dust.
These different components of turbulence fields at different scales of the street geometry are composed to define a set of operational and numerical models for the dispersion dynamics at the canyon scale of two classes of PM10 pollutants, corresponding to a Soot and a road dust components.
The deposition and the resuspension of pollutants are described by resistance and filtration models on porous asphalts, inserting the corresponding terms in the dispersion equations as
suitable boundary conditions on the ground.
We estimate the resuspension fraction of traffic-related PM10 emissions at the tailpipe, through a simplified linear-emission model, considering representative data describing traffic statistics coming from empirical data.
Profile laws of resuspension factors are drawn, for different vehicles geometries and velocities, and how resuspension changes with different asphalt characteristics.
The results are applied to typical traffic situations in the city of Milan, studying the effect of implementations of different reduction scenarios to the total amount of traffic-related PM10 emissions.
The results point at a new approach to the local PM10 reduction policies, based on more effective asphalt design and maintenance.
Finally, we apply one of the dispersion operational models to the case of a congested urban traffic configuration in a canyon street, in order to obtain the pollutant spatial distribution.
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Slavin, Courtney Natasha. "The Relationship Between Traffic Signals and Pedestrian, Bicyclist and Transit User Exposure in Urban Areas." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/616.
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Improving the efficiency of traffic operations along arterials is currently a priority for many agencies as their roadway infrastructure is built out to the largest possible capacity within the urban environment. Many advanced systems are being implemented to optimize traffic signal timing. Air quality is typically not a consideration when these decisions are made. The relationship between exposure to air pollution and traffic signal timing has not been fully explored by other researchers. This study is the first research effort to combine detailed traffic signal timing data (at 5 second intervals) and air pollutant exposure data. Results show that longer green time along the busy arterial reduces pollutant levels, while increased volume per cycle increases pollutant levels. This research quantifies the factors that contribute to pedestrian, bicyclist, and transit user exposure at a busy intersection along an urban arterial. The factors include traffic signal timing, weather related variables, traffic volumes, and heavy vehicle and bus presence. Additionally, the impact of an adaptive traffic signal system on air quality is assessed to understand the implications of signal timing on air pollutant exposure.
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Ma, Xiaoyi [Verfasser], and Dieter [Akademischer Betreuer] Schramm. "Effects of Vehicles with Different Degrees of Automation on Traffic Flow in Urban Areas / Xiaoyi Ma ; Betreuer: Dieter Schramm." Duisburg, 2021. http://d-nb.info/123032271X/34.
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Andersson, Lovisa. "An application of Bayesian Hidden Markov Models to explore traffic flow conditions in an urban area." Thesis, Uppsala universitet, Statistiska institutionen, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-385187.
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This study employs Bayesian Hidden Markov Models as method to explore vehicle traffic flow conditions in an urban area in Stockholm, based on sensor data from separate road positions. Inter-arrival times are used as the observed sequences. These sequences of inter-arrival times are assumed to be generated from the distributions of four different (and hidden) traffic flow states; nightly free flow, free flow, mixture and congestion. The filtered and smoothed probability distributions of the hidden states and the most probable state sequences are obtained by using the forward, forward-backward and Viterbi algorithms. The No-U-Turn sampler is used to sample from the posterior distributions of all unknown parameters. The obtained results show in a satisfactory way that the Hidden Markov Models can detect different traffic flow conditions. Some of the models have problems with divergence, but the obtained results from those models still show satisfactory results. In fact, two of the models that converged seemed to overestimate the presence of congested traffic and all the models that not converged seem to do adequate estimations of the probability of being in a congested state. Since the interest of this study lies in estimating the current traffic flow condition, and not in doing parameter inference, the model choice of Bayesian Hidden Markov Models is satisfactory. Due to the unsupervised nature of the problematization of this study, it is difficult to evaluate the accuracy of the results. However, a model with simulated data and known states was also implemented, which resulted in a high classification accuracy. This indicates that the choice of Hidden Markov Models is a good model choice for estimating traffic flow conditions.
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Mariotte, Guilhem. "Dynamic Modeling of Large-Scale Urban Transportation Systems." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSET010/document.
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La congestion en milieu urbain est un enjeu majeur que ce soit d’un point vue économique, social ou environnemental. À court et moyen terme, l’utilisation de la simulation dynamique du trafic routier peut permettre d’analyser et de guider des politiques d’optimisation des infrastructures existantes. Aujourd’hui, du fait de la complexité des systèmes de transport, les outils de modélisation classiques sont limités à des échelles géographiques peu étendues (de l’ordre du quartier). À grande échelle, le temps de calcul devient rapidement un facteur limitant tout comme le calibrage et la scénarisation. Néanmoins les dernières décennies ont vu l’apparition d’une nouvelle génération de modèles bien adaptés aux métropoles urbaines. Ceux-ci sont basés sur une relation phénoménologique entre la production de déplacements et le nombre de véhicules dans une zone spatiale d’un réseau routier, appelée Diagramme Fondamental de Zone (Macroscopic Fundamental Diagram, MFD). Cette relation, validée empiriquement sur de nombreuses villes, a permis d’étudier différentes méthodes de contrôle du trafic pour une ville entière, mais a été peu utilisée à des fins de prévision de la congestion. L’objectif de cette thèse est de proposer un premier outil opérationnel de simulation et d’analyse des grands réseaux de métropoles, en utilisant et développant les modèles de trafic basés sur la relation MFD. Cet outil doit posséder un cadre théorique cohérent qui puisse convenir à des applications telles que la prévision d’états de trafic, le développement de nouvelles politiques de contrôle, l’estimation de pollutions liées au trafic, etc. Les contributions de la thèse portent sur deux aspects. Le premier est l’analyse des propriétés mathématiques et physiques des modèles existants, en incluant une formalisation complète de la gestion de plusieurs longueurs de parcours au sein d’une même zone urbaine. En particulier, cette formalisation traite de la distinction des trajets internes à la zone et des problèmes de flux convergents et divergents pour les trajets traversant la zone lorsque la congestion se propage d’une zone à l’autre. Le deuxième aspect est la proposition d’un nouveau modèle basé sur la distance individuelle parcourue à l’intérieur d’une zone urbaine (trip-based). Cette approche permet d’individualiser les usagers (auparavant représentés sous forme de flux continus) et donc de définir plus finement leurs caractéristiques, en vue de coupler leurs déplacements à des modèles d’affectations sur différentes routes. Enfin, des exemples d’application illustrant diverses collaborations sont donnés en dernière partie de la thèse. La simulation du trafic sur l’aire urbaine du Grand Lyon (France) y est présentée, ainsi que de nouveaux modules de modélisation de la recherche de parking ou de contrôle périphérique. Cette thèse est partie intégrante d’un projet européen ERC intitulé MAGnUM : Approche multi-échelle et multimodale de la modélisation du trafic pour une gestion durable de la mobilité urbaineCongestion in urban areas has become a major issue in terms of economic, social or environmental impact. For short or mid term, using dynamic road traffic simulation can help analyzing and providing guidelines to optimization policies of existing infrastructures. Today, because of the complexity of transport systems, classical modeling tools are limited to small geographical areas (of a district size). Computational time, together with simulation calibration, are notably very constraining at large scales. However, a new generation of models designed for metropolitan areas has arisen over the past decades. These models are based on a phenomenological relationship between travel production and the number of vehicles in a given spatial area of a road network, known as the Macroscopic Fundamental Diagram (MFD). This relationship, supported by empirical evidences from several cities around the world, has allowed the study of different traffic control schemes at a whole city scale, but was rarely used for traffic state forecasting. The aim of this PhD is to propose an efficient modeling tool, based upon the concept of MFD, to simulate and analyze traffic states in large metropolitan areas. The theoretical framework of this tool must be consistent and applicable for traffic state forecasting, development of new control policies, traffic emission estimation, etc. There are two major contributions in this PhD. The first one is analyzing the mathematical and physical properties of existing models, and formalizing the dynamics of several trip lengths inside the same urban zone. In particular, this formalization distinguishes between internal trips and trips crossing the zone. Flow merging and diverging issues are also addressed when congestion propagates from one zone to another. The second contribution is proposing a new trip-based model based on individual traveled distance. This approach allows to treat users independently (previously represented with continuous flows), and thus to define their characteristics more precisely to couple their trips with assignment models on different paths. Finally, examples of application from various collaborations are given in the last part of this thesis. It includes a simulation study of the Grand Lyon urban area (France), as well as new modules to simulate search-for-parking or perimeter control. This PhD is part of a European ERC project entitled MAGnUM: Multiscale and Multimodal Traffic Modeling Approach for Sustainable Management of Urban Mobility
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Goulart, Elisa Valentim. "Flow and dispersion in urban areas." Thesis, University of Reading, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.578021.
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The threat of deliberate or accidental releases of harmful substances in urban areas makes understanding atmospheric flow and dispersion important. When the source is located within the urban canopy the highest concentrations are in the short-range, i.e. less than lkm, where the dispersion is strongly affected by the presence of buildings. Understanding the processes that govern point source dispersion in the short range is important in order to develop a dispersion model for the use of emergency responders. Some questions are addressed based on this scenario: (i) What are the main flow mechanisms in urban areas? (ii) How does a ground source disperse in the short-range? (iii) How can we model short-range dispersion for fast response applications? To answer these questions data from direct numerical simulations (DNS) over arrays of buildings are analysed. In this study two regular building arrays are used (aligned and staggered) to determine the influence of geometry on near-field dispersion. The external flow is either parallel to or oblique (45°) to the building array. Analysis of the flow field reveals a number of flow features relevant for dispersion. Firstly, when the wind is oblique to the buildings the flow divides around them, thereby causing topological splitting. Secondly, the component of the wind parallel to the streets causes channelling along the street axis. Thirdly, the flow within intersections is complex and three-dimensional, especially for oblique wind directions. Fourthly, recirculation
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Grau, Mariani Rafael. "A demand-responsive traffic control system for urban areas." Doctoral thesis, Universitat Politècnica de Catalunya, 1995. http://hdl.handle.net/10803/399670.
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The goal of this Ph.D. Thesis is the design, development and testing of a 'well-engineered system' aimed at the demand-responsive traffic control of urban areas. Because of the author's background -software engineering-, a 'well-engineered system' means a system that is both efficient at performing its task in a wide range of conditions and also that has been built from the robust design's and ease-of-use's points of view. The work has proceed in four steps and, accordingly, this document has been divided in four parts that are briefly desc1ibed here.
PART I is, mainly, an introduction to the subject. It introduces the concept of demand responsiveness in traffic control, providing a historical perspective from traditional fixed control systems to current modern demand-responsive systems. The part concludes with a study of areas where research and improvement is needed. All of these areas are considered in the following parts, where some solutions are proposed.
PAR T II presents the design, development and preliminary tests of a demand responsive traffic control system, CARS V l, intended to operate in signalized urban areas: networks, arte1ials, and isolated intersections. A graphical user interface, X-Windows and DecWindows compliant, allows the user to specify network characteristics in a friendly and intuitive manner, without the need to be acquainted with the actual modeling. The system features an underlying simulation system and a prediction model based on real-time measured conditions, implements a centralized approach based on small variations, and has flexible detector positioning-and-number requirements.
PART III presents the design of a simulation environment, named GETRAM, that solves the difficulties in testing CARS that were discussed at the end of the previous part. We have seen that these difficulties are inherent in the traffic engineer having to use diverse models in order to analyze a traffic network, and that there is the need for a system to salve it. GETRAM provides a unified framework integrating various types of traffic models and tools for traffic analysis, sharing a DataBase, a graphical editor and a mod le for results presentation. The traffic network can be partitioned into views, hierarchically organized polygons in the real world, so that, for example, a simulation model applies only to one of these restricted areas. Network statcs produced by one model can be used as a starting point by another modcl. I n order to ease the task of integrating a new model or analysis tool, a library of object-based high-level functions provide a view-aware access to the DataBase, maintaining consistency. Included in this Ph.D. thesis are the design of the whole environment -DataBase, G ETR AM API, and graphical editor - and the development of the DataBase and GETRAM API.
PART IV starts from the demand-responsive traffic control system developed in PART II, CARS V l , and improves it in various respects. First, in order to ease the task of testing the system, it is integrated into the traffic modeling and analysis environment described in PART III. Second, certain parts that directly influence to the effectiveness of the system, such as control timing, adaptive control logics and communication with the controllers, are revised or totally redone. A suite of tests has been applied to the resulting system, CARS V2, in the four scenarios desc1ibed in PART 11. Finally, to further testing the system and taking advantage of the fact of having real-world data available, it is compared against a vehicle-actuated control at an isolated junction.El objetivo de esta tesis es el diseño, desarrollo y test por simulación microscópica de un sistema autoadaptativo apto para cruces aislados, arterias y redes urbanas complejas. El sistema produce planes de control acíclicos y presenta unos requerimientos de tiempo real muy flexibles debidos a utilizar una nueva secuencia cíclica de tareas en la que se predice el estado del sistema a corto término antes de probar planes de control alternativos. Estas pruebas se realizan mediante un modelo interno de simulación que sigue un enfoque mesoscópico a base de paquetes de vehículos de velocidad variable, con el que se consigue modelizar la dinámica de colas de vehículos de forma más exacta que con los sistemas actualmente existentes. Esto da una ventaja, corroborada en los test, en condiciones de flujo altas, con lo que el sistema de controles es capaz de mantener una buena efectividad en un amplio rango de condiciones de tráfico. El sistema viene acompañado de un entorno de simulación y test que aporta un alto grado de integración y de facilidad de uso, a lo largo de todo el proceso de especificación de geometría, parámetros y ejecución de simulación se mantiene una vista de la red de tráfico altamente realista.
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Bostock, Adam K. "Prediction and reduction of traffic pollution in urban areas." Thesis, University of Nottingham, 1994. http://eprints.nottingham.ac.uk/14352/.
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This thesis is the result of five years research into road traffic emissions of air pollutants. It includes a review of traffic pollution studies and models, and a description of the PREDICT model suite and PREMIT emissions model. These models were used to evaluate environmentally sensitive traffic control strategies, some of which were based on the use of Advanced Transport Telematics (ATT). This research has improved our understanding of traffic emissions. It studied emissions of the following pollutants: carbon monoxide (CO), hydrocarbons (HC) and oxides of nitrogen (NOx). PREMIT modelled emissions from each driving mode (cruise, acceleration, deceleration and idling) and, consequently, predicted relatively complex emission characteristics for some scenarios. Results suggest that emission models should represent emissions by driving mode, instead of using urban driving cycles or average speeds. Emissions of NOx were more complex than those of CO and HC. The change in NOx, caused by a particular strategy, could be similar or opposite to changes in CO and HC. Similarly, for some scenarios, a reduction in stops and delay did not reduce emissions of NOx. It was also noted that the magnitude of changes in emissions of NOx were usually much less than the corresponding changes in CO and HC. In general, the traffic control strategies based on the adjustment of signal timings were not effective in reducing total network emissions. However, high emissions of pollutants on particular links could, potentially, be reduced by changing signal timings. For many links, mutually exclusive strategies existed for reducing emissions of CO and HC, and emissions of NOx. Hence, a decision maker may have to choose which pollutants are to be reduced, and which can be allowed to increase. The environmental area licensing strategy gave relatively large reductions in emissions of all pollutants. This strategy was superior to the traffic signal timing strategies because it had no detrimental impact on the efficiency of the traffic network and gave simultaneous reductions in emissions of CO, HC and NOx.
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Di, Sabatino Silvana. "Flow and pollutant dispersion in urban areas." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615192.
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Hamlyn, David Peter Denis. "Flow and exchange processes in urban areas." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613232.
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Martin, Peter Terence. "Urban traffic movement prediction from automatic flow detection." Thesis, University of Nottingham, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334986.
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O'Keeffe, Joanne. "Monitoring and modelling of nitrogen dioxide in urban areas." Thesis, Imperial College London, 1997. http://hdl.handle.net/10044/1/8131.
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Mongeot, Helene. "Traffic incident modelling in mixed urban networks." Thesis, University of Southampton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286751.
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Najaf, Pooya. "A macro-level analysis of traffic and pedestrian safety in urban areas." Thesis, The University of North Carolina at Charlotte, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10245444.
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The main objective of this research is to examine the effect of city-level urban characteristic, such as urban form and trip generation factors, on traffic safety in general and pedestrian safety in particular. For this purpose, the information for 100 major Urban Areas (UAs) in the United States in 2010 is studied. Factor analysis is applied to construct latent variables from multiple observed variables to measure and describe urban form, macro-level trip generation, citywide transportation network features and traffic safety. Structural Equation Modeling (SEM) is then used to investigate how city-level urban form and trip generation affect traffic safety directly and indirectly (through mediators of transportation network features).
Based on the statistical analysis, it is found that encouraging the use of non-driving transportation modes and controlling traffic congestion, as significant mediators, are effective policies to increase overall traffic safety and pedestrian safety, respectively. In this regard, urban areas with a more even spatial distribution of job-housing balance (more polycentricity), more uniform spatial distribution of different social classes, higher urban density (less sprawl), and more connectivity in their transportation network (more accessibility) have the safest urban form designs.
Moreover, mixed land-use designs with provided local access to services and amenities, food and beverage centers, and religious organizations, followed by strict pedestrian safety standards for neighborhoods are the safest type of land use designs in urban areas. In addition, regulating the off-peak hours allowed time for heavy vehicles and changing the work schedule of workers who do not reside in the urban area can also help city planners to increase traffic safety.
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Cowburn, G. J. "Bayesian mixture modelling with application to road traffic flow." Thesis, University of Sunderland, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269160.
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Stenberg, Josefin, and Sabina Syed. "Optimal Multi-Commodity Network Flow of Autonomous Vehicles in Urban Traffic." Thesis, KTH, Skolan för teknikvetenskap (SCI), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-297491.
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The focus of this thesis was to find, visualize and analyze the optimal flow of autonomous vehicles in urban traffic with respect to fuel consumption using linear optimization. Two different formulations based on multi-commodity network flow were implemented which resulted in a static and a dynamic model of the traffic. The static model was applied to Kungsholmen, an urban district in central Stockholm, Sweden, while the dynamic model was considered on a small-scale. These models led to large linear programs which were solved by applying different algorithms to the problems in various software. The results suggested that the developed models were adequate approximations of the urban traffic flow for the chosen parameter set-ups. It was concluded that the traffic in a system of autonomous vehicles may be optimally planned using similar models as formulated in this study.
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Fong, Pui San. "Assessment of roundabout in urban road network :a case study of Macau." Thesis, University of Macau, 2017. http://umaclib3.umac.mo/record=b3691706.
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Zhang, Xiaoyan. "The dynamic behaviour of road traffic flow : stability or chaos?" Thesis, Middlesex University, 1995. http://eprints.mdx.ac.uk/10685/.
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The objective of this thesis is to investigate the dynamic behaviour of road traffic flow based on theoretical traffic models. Three traffic models are examined: the classical car-following model which describes the variations of speeds of cars and distances between the cars on a road link, the logit-based trip assignment model which describes the variations of traffic flows on road links in a road network, and the dynamic gravity trip distribution model which describes the variations of flows between O-D pairs in an O-D network. Some dynamic analyses have been made of the car-following model in the literature (Chandler et al., 1958, Herman et al., 1959, Disbro & Frame, 1990, and Kirby and Smith, 1991). The dynamic gravity model and the logit-based trip assignment model are both suggested by Dendrinos and Sonis (1990) without detailed analysis. There is virtually no previous dynamic analysis of trip distribution, although there are some dynamic considerations of trip assignment based on other assignment models (Smith, 1984 and Horowitz, 1984). In this thesis, the three traffic models are considered as dynamical systems. The variations of traffic characteristics are investigated in the context of nonlinear dynamics. Equilibria and oscillatory behaviour are found in all three traffic models; complicated behaviour including period doubling and chaos is found in the gravity model. Values of parameters for different types of behaviour in the models are given. Conditions for the stability of equilibria in the models are established. The stability analysis of the equilibrium in the car-following model is more general here than that in the literature (Chandler et al., 1958, Herman et al., 1959). Chaotic attractors found in the gravity model are characterized by Liapunov exponents and fractal dimension. The research in this thesis aims at understanding and predicting traffic behaviour under various conditions. Traffic systems may be monitored, based on these results, to achieve a stable equilibrium and to avoid instabilities and chaos.
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Limpattanasiri, Wisit. "MAXIMAL COVERING LOCATION MODELS OF EMERGENCY AMBULANCE CONSIDERING HEAVY TRAFFIC CONGESTION IN URBAN AREAS." 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/180486.
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Lindström, Olsson Anna-Lena. "Facotes that influence choice of travel mode in major urban areas." Licentiate thesis, KTH, Infrastructure, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1627.
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Problems associated with traffic, such as traffic congestionand pollution, have occurred in major urban areas in particulardue to the increased use of cars. One possible way to reducethe use of cars is to replace commuter trips by car with othermodes of transport, such as a combination of car and publictransport called Park&Ride. The aim of this thesis was tounderstand more about factors influencing the choice of modeand to find measures that could attract car drivers to Park&Ride. A stated preference survey has been conducted inorder to quantify some standard factors. The factors used inthis stated choice experiment were: security at the lot,availability of spaces at the parking lot, costs at the parkinglot and walking distances between the parking space and thestation. The results indicate that security at the Park&Ride facility is important. Both sexes assign a high value tosecure parking, but women are more willing to pay for lights atan unguarded parking lot. The results reveal that parkingfacilities, such as free parking and short distance betweenparking place and work at work, influence peoples choiceof mode. A general conclusion is that there is potential forincreasing the use of Park&Ride facilities, especiallyamong women and respondents over 30 years.
Key words:Mode choice, valuation, traffic reduction,stated preference, factors, Park&Ride
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Lindström, Olsson Anna-Lena. "Factors that influence choice of travel mode in major urban areas." Licentiate thesis, KTH, Infrastruktur, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1627.
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Problems associated with traffic, such as traffic congestionand pollution, have occurred in major urban areas in particulardue to the increased use of cars. One possible way to reducethe use of cars is to replace commuter trips by car with othermodes of transport, such as a combination of car and publictransport called Park&Ride. The aim of this thesis was tounderstand more about factors influencing the choice of modeand to find measures that could attract car drivers to Park&Ride. A stated preference survey has been conducted inorder to quantify some standard factors. The factors used inthis stated choice experiment were: security at the lot,availability of spaces at the parking lot, costs at the parkinglot and walking distances between the parking space and thestation. The results indicate that security at the Park&Ride facility is important. Both sexes assign a high value tosecure parking, but women are more willing to pay for lights atan unguarded parking lot. The results reveal that parkingfacilities, such as free parking and short distance betweenparking place and work at work, influence peoples choiceof mode. A general conclusion is that there is potential forincreasing the use of Park&Ride facilities, especiallyamong women and respondents over 30 years. Key words:Mode choice, valuation, traffic reduction,stated preference, factors, Park&RideNR 20140805
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Schrank, David Lynn. "Identification of the relationship between economic and land use characteristics and urban mobility at the macroscopic level in Texas urban areas." Texas A&M University, 2004. http://hdl.handle.net/1969.1/1245.
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Traffic congestion continues to be a growing problem for cities of all sizes in the United States. Transportation agencies in urban areas are facing the difficult challenges of providing an efficient and reliable transportation system for residents and businesses despite ever-diminishing resources. Agencies in these areas need the capability of determining the future benefits of transportation investments so they can communicate this information to the public. This capability is difficult for many agencies, especially some of the smaller ones, who may not have the resources to make these analyses without turning to expensive long-range models.
This research uses readily available socio-economic, land use, and traffic congestion data from many of the Texas urban areas to create prediction models to estimate future traffic congestion levels. Many of the transportation agencies that could utilize this tool do not have the resources to deal with large complex databases. Thus, basic information such as income, employment, single family residences, or commercial properties, to name a few, is used to create the predictions models.
Results from this research show that traffic congestion prediction models can be created from socio-economic and land use data. These models were created for eighteen individual Texas urban areas and several combinations of areas. Transportation agencies could use the results of this research to estimate future congestion in their respective areas.
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Camynta-Baezie, Gylbet. "Multi-class pseudo-dynamic traffic assignment in a signalized urban road network." Thesis, University of Newcastle Upon Tyne, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313502.
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Valdes, Diaz Didier M. "Integrated information and traffic control strategies for congested urban freeway corridors /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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Kenworthy, J. R. "Driving cycles, urban form and transport energy /." Access via Murdoch University Digital Theses Project, 1986. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20051103.145933.
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Wang, Shi'an. "Stochastic Dynamic Model of Urban Traffic and Optimum Management of Its Flow and Congestion." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37254.
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There are a lot more roads being built periodically in most of the countries with the advancement of modern society. In order to promote the overall traffic flow quality within different cities, city traffic management has been playing a more and more essential role during the last few decades. In recent years, a significantly increasing attention has been paid to the management of traffic flow in major cities all over the world.
In this thesis, we develop a stochastic dynamic model for urban traffic along with physical constraints characteristic of intersections equipped with traffic light. We assume that the incoming traffic to each stream in an intersection is amenable to the Poisson random process with variable intensity (mean). We introduce expressions for traffic throughput, congestion as well as operator's waiting time for the typical intersection in a city and hereafter define an appropriate objective functional. Afterwards, we formulate an optimization problem and propose the sequential (or recursive) algorithm based on the principle of optimality (dynamic programming) due to Bellman. The solution if implemented is expected to improve throughput, reduce congestion, and promote driver's satisfaction. Because the dynamic programming method is computationally quite intensive, we consider the scenario that one unit traffic stream stands for a specific number of vehicles which actually depends on the volume of traffic flow through the intersection.
The system is simulated with inputs described by several distinct nonhomogeneous Poisson processes. For example, we apply the typical traffic arrival rate in Canada with morning peak hour at around 7:30 AM and afternoon peak hour at around 4:30 PM whilst it is also applied with morning rush hour at about 8:00 AM and afternoon rush hour at about 6:00 PM like in China. In the meanwhile, we also present a group of numerical results for the traffic arrival rates that have shorter morning peak-hour period but longer afternoon rush hour period. This may occasionally happen when there are some social activities or big events in the afternoon. In addition, another series of experiments are carried out to illustrate the feasibility of the proposed dynamic model based on the traffic arrival rates with only one peak-hour throughout the whole day. The system is simulated with a series of experiments and the optimization problem is solved by dynamic programming based on the proposed algorithm which gives us the optimal feedback control law. More specifically, the results show that both the optimal traffic light timing allocated for each stream and the congestion broadcast level (CBL) of each road segment during each time segment are found. Accordingly, the corresponding optimal cost can be found for any given initial condition. It is reasonably believed that this stochastic dynamic model would be potentially applicable for real time adaptive traffic control system.
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Sutomo, Heru. "Appropriate saturation flow at traffic signals in Javanese cities : a modelling approach." Thesis, University of Leeds, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305681.
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Ahmed, Istiak. "Using the Macroscopic Fundamental Diagram to Characterize the Traffic Flow in Urban Network." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/78468.
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Various theories have been proposed to describe vehicular traffic flow in cities on an aggregate level. This dissertation work shows that a number of MFDs exist in an urban network. The number of MFDs basically indicate the existence of different levels of service on different network routes. It also demonstrate that the modification of control strategy can optimize the signal timing plan for the links with high congestion and spillbacks. With the proposed control strategy, the location of points are shifted from lower MFDs to upper MFDs which means the congestion are reduced and the overall network traffic flow operation is improved. In this thesis, the emergency vehicle preemption (EVP) operation is also evaluated by using the MFDs. The concept of MFD can help to illustrate the effect on various types of roads due to EVP operation. The results show that the volume of links along the emergency route is increased and the volume of other links closed to the emergency route is decreased due to preemption. The researchers and practitioners can apply the proposed approach to identify the affected links and minimize the total network delay during EVP.Master of Science
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Papageorgiou, Asterios. "Emerging technologies for climate-neutral urban areas : An Industrial Ecology perspective." Licentiate thesis, KTH, Resurser, energi och infrastruktur, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-292648.
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The ever-increasing concentration of human activity in urban areas induces environmental problems beyond their boundaries on scales ranging from local to regional to global, such as resource depletion, land degradation, air and water pollution and climate change. Human-induced climate change is widely acknowledged as one of the greatest sustainability challenges of the present century and it is inextricably linked to urbanization. As a response to climate change, urban areas around the world have committed to reach climate neutrality within the next decades. In this context, the deployment of new technologies can have a key role in achieving carbon neutrality in urban areas. As new technologies emerge, it is essential to assess their environmental performance considering the broader systems context in order to ensure that they can indeed contribute to achieving climate neutrality without compromising environmental sustainability. This thesis aims is to provide insight on the environmental performance of emerging technologies that can be deployed in urban areas in order to contribute to achieving climate neutrality. The two technologies in focus are grid-connected solar microgrids and biochar-based systems for treatment of biomass waste and remediation of contaminated soil. The methods applied to conduct the environmental assessments and fulfil the aim of the thesis are: case studies, Life Cycle Assessment (LCA), Material and Energy Flow Analysis and Substance Flow Analysis. Moreover, as part of the research efforts, a spreadsheet model based on LCA data was developed. The assessment of the solar microgrid highlighted the importance of using explicit spatial and temporal boundaries when analyzing the environmental performance of energy systems, as it can increase the accuracy of the results. It also revealed that the choice of modeling approach can influence the results of the assessment, which motivates the application of different methodological approaches. Within this context, the assessment showed that in a short-term perspective the integration of a grid-connected urban solar microgrid into the Swedish electricity grid would not contribute to climate change mitigation, as solar electricity from the microgrid would displace grid electricity with lower carbon intensity. The assessment also indicated that operational and structural changes in the microgrid could reduce its climate change impact, albeit not to the extent to generate GHG emission abatements. The assessment of the biochar-based systems showed that these systems have many environmental benefits compared to incineration of waste and landfilling of contaminated soil. They have great potential to contribute to achieving climate neutrality, as they can provide net negative GHG emissions, owing mainly to carbon sequestration in the biochar. Between the two biochar-based systems, a system for on-site remediation can provide additional environmental benefits, as it can lead to more efficient use of resources. However, these systems also entail environmental trade-offs due to increased consumption of auxiliary electricity, while the extent of ecological and human health risks associated with the reuse of biochar-remediated soils is for the moment unknown.Den ständigt ökande koncentrationen av mänsklig aktivitet i urbana områden orsakar miljöproblem utanför deras gränser på skalor som sträcker sig från lokal till regional till global, såsom utarmning av resurser, markförstöring, luft- och vattenföroreningar och klimatförändring. Mänskligt driven klimatförändring är allmänt erkänd som en av de största hållbarhetsutmaningarna under nuvarande seklet och den är nära kopplad till urbanisering. Som ett svar på klimatförändringen har urbana områden runt om i världen åtagit sig att nå klimatneutralitet inom de närmaste decennierna. I detta sammanhang kommer införandet av ny teknik ha en nyckelroll för att uppnå klimatneutralitet i stadsområden. När ny teknik dyker upp är det viktigt att bedöma dess miljöprestanda med hänsyn till den bredare systemkontexten för att säkerställa att tekniken verkligen kan bidra till att uppnå klimatneutralitet utan att kompromissa med miljömässig hållbarhet. Denna avhandling syftar till att ge insikt om miljöprestanda för framväxande teknik som kan användas i urbana områden för att bidra till att uppnå klimatneutralitet. De två teknikerna i fokus är nätanslutna solmikronät och biokolbaserade system för behandling av biomassavfall och sanering av förorenad mark. Metoderna för att genomföra miljöbedömningarna och uppfylla avhandlingens syfte är: fallstudier, livscykelanalys (LCA), material- och energiflödesanalys och substansflödesanalys. Som en del av forskningsinsatserna utvecklades dessutom en kalkylmodell baserad på LCA-data. Analysen av solmikronätet visade att det är viktigt att använda explicita rums- och tidsgränser vid analys av energisystemens miljöprestanda, eftersom det kan öka resultatens noggrannhet. Analysen visade också att valet av modelleringsmetod kan påverka resultatet, vilket motiverar en användning av flera olika metoder. Inom detta sammanhang visade bedömningen att i ett kortsiktigt perspektiv skulle integrationen av ett nätanslutet urbant solmikronät i det svenska elnätet inte bidra till att begränsa klimatförändringen, eftersom solenergi från mikronätet skulle ersätta el med lägre klimatpåverkan. Bedömningen indikerade också att operativa och strukturella förändringar i mikronätet kunde minska mikronätets klimatförändrings påverkan, om än inte i sådan utsträckning att det skulle ge växthusgasutsläppsbesparingar. Bedömningen av de biokolbaserade systemen visade att dessa system har många miljöfördelar jämfört med förbränning av avfall och deponering av förorenad mark. De har stor potential att bidra till att uppnå klimatneutralitet, eftersom de kan ge nettonegativa utsläpp av växthusgaser, främst på grund av kolbindning i biokol. Vi jämförelse av de två biokolbaserade systemen så kan ett system för sanering på plats ge ytterligare miljöfördelar, eftersom det kan leda till en mer effektiv resursanvändning. Dessa system medför emellertid också miljöavvägningar på grund av ökad förbrukning av elektricitet, medan omfattningen av ekologiska och människors hälsorisker förknippade med återanvändning av biokolbehandlad jord ännu är okända.
QC 20210419
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Zhou, Yi. "The macroscopic fundamental diagram in urban network: analytical theory and simulation." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/49111.
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The Macroscopic Fundamental Diagram (MFD) is a diagram that presents a relationship between the average flow (production) and the average density in an urban network. Ever since the existence of low scatter MFD in urban road network was verified, significant efforts have been made to describe the MFD quantitatively. Due to the complexity of the traffic environment in urban networks, an accurate and explicit expression for the MFD is not yet developed and many recent research efforts for MFD rely on computer simulations. On a single corridor, an analytical approximation model for the MFD exists. However, this thesis expanded this theory in two directions. First, we specialize the method for models with equal road length on the corridor, which greatly reduces the complexity of the method. We introduce the adoption of seven straight cuts in approximation. Computer simulations are conducted and show a high compatibility with the approximated results. However the analytical approximation can only be applied with the assumption of constant circulating vehicles in the system without turnings and endogenous traffics. Secondly, we show that turnings and endogenous traffic can bring various impact on the shape of the MFD, the capacity, the critical density, the variance in density and cause a phenomenon of clustered traffic status along the MFD curve. Furthermore, the simulation using stochastic variables reveals that the variance in turning rates and endogenous traffic don’t have significant impact on the MFD. This discovery enables studies to focus on scenarios with deterministic parameters for those factors. While traditional objective of engineering for network is to maximize capacity and widen the range for the maximum capacity, our results indicate that traffic stability at the maximum performance is poor if the system does not stay constantly in equilibrium status. This thesis provides insights into the factors that affect the shape of the MFD by analytical approximation and simulation.
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Mlunga, Lydia. "Material flow analysis of wood fuel in small urban areas : the case of Tsumeb Namibia." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20080.
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Thesis (MPhil)--Stellenbosch University, 2012.ENGLISH ABSTRACT: The current ways in which the human population continues to utilise natural resources in order to satisfy their lifestyle remains unsustainable. One such activity is the use of biomass resources mainly for cooking, heating and boiling water which sustains an estimated 2.4 billion people living in developing countries. Biomass not only is the fourth largest energy source after coal, oil and natural gas, but it is currently the largest renewable energy option and yet it has received minimal attention especially from current energy debates in developing countries. Literature shows cases of cities that remain ‘uncertain’ of their development agendas (regarding energy). The uncertainty is a result of most cities relying heavily on fossil fuel which is in most cases imported which minimises the possibilities of cities to come up with sustainable energy projects. As cities continue to grow the supply of this unsustainable energy puts cities in an uncertain position regarding the future energy sources of their cities. There are cities that have now realised the importance of understanding the flow of wood fuels in order to put in measures that can help manage the resource better. Most of them use a GIS-based tool, Wood fuel Integrated Supply Demand Overview Mapping Model (WISDOM) which was developed to analyse the wood fuel supply and demand spatial patterns. Tsumeb is currently also moving in an ‘uncertain’ direction especially when it comes to the energy needs of the town characterised by high electricity tariffs, increased population leading to clearing of land, high unemployment rate and distorted priorities (of the municipality). The Material Flow Analysis (MFA) of wood fuels in Tsumeb is highly dominated by the informal sector. It remains unregulated and no attempt has been made to determine the household energy flow. This study is the first attempt to determine the flow of this very important household energy resource used more especially in winter. The survey revealed that firewood is used to prepare one to two meals a day especially in the townships where the households opt to consume one meal a day. Some consumers collect their own firewood and often have to purchase wood fuels to meet their individual needs. The wood fuel retailers that were surveyed in the study obtain their wood fuels from local commercial farmers and use charcoal produced both in Namibia and South African. The commercial farmers also form part of the informal sector as they supply some of the informal suppliers and consumers. Some informal suppliers resort to open forests located far from their homes, putting a lot of strain on the transport mechanisms. In order to ensure a sustainable supply of household energy in Tsumeb, It is inevitable that a new paradigm is needed in the current planning and development process of the town. Therefore for an effective implementation of policies aimed at developing wood fuels, local conditions as well as the local wood fuel flows must be understood, grassroots initiatives need to be built and community participation should be encouraged in order to get a collective approach to issues that concerns and threatens their livelihoods.
AFRIKAANSE OPSOMMING: Die wyse waarop die mensdom natuurlike hulpbronne aanwend om aan die eise van hul leefstyl te voldoen, bly onvolhoubaar. Een sodanige aktiwiteit is die gebruik van biomassahulpbronne, hoofsaaklik vir kosvoorbereiding en ruimte- en waterverhitting. Biomassahulpbronne onderhou geraamde 2,4 miljard inwoners van ontwikkelende lande. Dit is nie net die grootste energiebron naas steenkool, olie en aardgas nie, maar is ook tans die belowendste bron van hernubare energie. Tog ontvang dit weinig aandag. Hoewel literatuur steeds merendeels oor gevalle handel wat ‘onseker’ is oor hul ontwikkelingsagendas, is daar tóg diegene wat uiteindelik besef hoe belangrik dit is om die vloei van houtbrandstof te begryp ten einde maatreëls te tref om dié hulpbron beter te bestuur. Die meeste van hierdie lande gebruik GIS-gebaseerde instrument, naamlik die WISDOM-model (“Wood-fuel Integrated Supply Demand Overview Mapping”), wat ontwikkel is om die ruimtelike patrone van houtbrandstofvraag en -aanbod te ontleed. Die Namibiese stad Tsumeb is een van die ‘onsekeres’, veral wat sy energiebehoeftes betref, en word gekenmerk deur hoë elektrisiteitstariewe, groeiende bevolking wat al hoe meer ontbossing tot gevolg het, hoë werkloosheidsyfers en verwronge prioriteite. Die materiaalvloeiontleding wat in hierdie studie met betrekking tot die houtbrandstof in Tsumeb onderneem is, word in groot mate deur die informele sektor oorheers. Hoewel die gebruik van houtbrandstof steeds ongereguleerd is, is geen poging tot dusver aangewend om die vloei van dié uiters belangrike huishoudelike energiebron, wat veral in die wintermaande gebruik word, te bepaal nie. Die opname het getoon dat brandhout gebruik word om een tot twee maaltye per dag te berei, veral in die townships waar die huishoudings meestal een keer per dag eet. Party verbruikers maak hulle eie brandhout bymekaar, maar moet steeds bykomende hout koop om in ál hulle behoeftes te voorsien. Die houtbrandstofhandelaars wat aan die opname deelgeneem het, bekom hul houtbrandstof van plaaslike kommersiële boere en van Namibiese sowel as Suid-Afrikaanse houtskoolverskaffers. Die kommersiële boere maak ook deel uit van die informele sektor, aangesien hulle sommige informele verskaffers en verbruikers van brandstof voorsien. Van die informele verskaffers wend hulle tot die plaaslike oop woud wat ver van hulle huise geleë is, en plaas sodoende heelwat druk op vervoerstelsels. Die enigste manier waarop Tsumeb sy huidige energie-onsekerheid te bowe kan kom, is deur nuwe benadering tot houtbrandstof in te stel. Om beleid met betrekking tot die ontwikkeling van houtbrandstof doeltreffend toe te pas, moet plaaslike omstandighede sowel Die enigste manier waarop Tsumeb sy huidige energie-onsekerheid te bowe kan kom, is deur nuwe benadering tot houtbrandstof in te stel. Om beleid met betrekking tot die ontwikkeling van houtbrandstof doeltreffend toe te pas, moet plaaslike omstandighede sowelDie enigste manier waarop Tsumeb sy huidige energie-onsekerheid te bowe kan kom, is deur nuwe benadering tot houtbrandstof in te stel. Om beleid met betrekking tot die ontwikkeling van houtbrandstof doeltreffend toe te pas, moet plaaslike omstandighede sowel Die enigste manier waarop Tsumeb sy huidige energie-onsekerheid te bowe kan kom, is deur nuwe benadering tot houtbrandstof in te stel. Om beleid met betrekking tot die ontwikkeling van houtbrandstof doeltreffend toe te pas, moet plaaslike omstandighede sowel as die plaaslike vloei van houtbrandstof dus beter begryp word; moet inisiatiewe op voetsoolvlak tot stand gebring word, en moet gemeenskapsdeelname aangemoedig word. Sodoende sal die mense van Tsumeb – huishoudings, owerhede én ondernemings – gesamentlik kan reageer op kwessies wat hul bestaan beïnvloed en bedreig.
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Qian, Gongbin. "Effectiveness of eco-driving during queue discharge at urban signalised intersections." Thesis, Queensland University of Technology, 2013. https://eprints.qut.edu.au/65352/1/Gongbin_Qian_Thesis.pdf.
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This research investigated the effectiveness of using an eco-driving strategy at urban signalised intersections from both the individual driver and the traffic flow perspective. The project included a field driving experiment and a series of traffic simulation investigations. The study found that the prevailing eco-driving strategy has negative impacts on traffic mobility and environmental performance when the traffic is highly congested. An improved eco-driving strategy has been developed to mitigate these negative impacts.
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Andersen, Ole Johan. "How Case-based Reasoning can be used to predict and improve Traffic Flow in Urban Intersections." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for datateknikk og informasjonsvitenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-20861.
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The traffic situation in urban areas has become a large problem over the recent years. Especially congestion during rush hours is becoming quite visible. Often, this can not be solved by simply building more roads, as most urban areas do not have the available physical space required. One way of solving these problems can be to focus on decreasing the number of vehicles. This can be done by increasing the amount of people traveling in each vehicle, or focusing on alternative transportation such as bicycle or public transport. Another way of utilising the existing infrastructure, is to improve the control of the traffic flow. In this thesis we present a prototype case-based reasoning (CBR) system for the purpose of controlling the traffic lights in an urban intersection. The system uses historical vehicle counts, obtained from an intersection in the city of Trondheim, before using this knowledge in order to make new signal plans for the intersection. jCOLIBRI is used as framework for the development of our CBR-system and evolutionary algorithms are used for weighting the case base. The traffic simulator Aimsun is used for the evaluation of our solution. Simulation results indicate that the CBR-system is able to satisfactory calculate signal plans based on the predicted traffic, in a variety of different scenarios.
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Bayareddy, Venkata Subbarao. "Determination of Ineffective Flow Areas in Bridge Modeling Using HEC-RAS by Locating Ineffective Flow Stations." University of Dayton / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1462356833.
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BARBOSA, IVANILDO. "ASSESSMENT OF THE IMPACT OF TRAFFIC ACCIDENTS ON THE FLOW OF URBAN ROADS BASED ON SPEED VALUES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2015. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=25823@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
INSTITUTO MILITAR DE ENGENHARIA
CENTRO TECNOLÓGICO DO EXÉRCITO
PROGRAMA DE EXCELENCIA ACADEMICA
Uma das preocupações das grandes cidades é a minimização dos efeitos do aumento da quantidade de veículos em circulação e dos acidentes que, consequentemente, tendem a ocorrer com maior frequência. Com a popularização e a miniaturização dos receptores GPS, a disponibilidade de valores de velocidade observados nas vias urbanas e a publicação de ocorrências de trânsito georreferenciadas em redes sociais, é agora possível avaliar as condições do trânsito quanto às reduções de velocidade. Contudo, é necessário filtrar os dados de tal forma a minimizar incertezas temáticas, espaciais e temporais. Esta tese propõe uma metodologia para a avaliação do impacto de acidentes de trânsito, empregando valores de velocidade. Para tanto, considera metodologias auxiliares para: (1) processamento de rotas rastreadas com GPS para identificar vias com maior circulação, calcular estatísticas das velocidades observadas e estimar o tráfego em vias de mão dupla, pela análise das direções do movimento; (2) representação do comportamento do tráfego a partir dos valores de velocidade registrados nas vias; (3) extração e seleção dos dados sobre acidentes extraídos do Twitter para identificar os possíveis efeitos desses acidentes nos valores de velocidade. As contribuições desta tese são: (1) avaliação do tráfego, em condições normais e após a ocorrência de acidentes, com base em valores de velocidade, de aquisição mais simples do que os valores de fluxo e concentração de tráfego; (2) emprego de publicações de eventos em redes sociais, permitindo rápido acesso à informação; (3) aplicação das avaliações em vias urbanas, em lugar de rodovias, o que implica em levar em consideração as interferências no tráfego inerentes às interseções, sinais de trânsito e fluxo de pedestres; e (4) uma metodologia para extração de estatísticas de velocidade a partir de dados GPS, enfatizando as possíveis fontes de erro existentes nos processos de map matching e classificação temporal.
A major concern in large cities is to minimize the effects of the increasing quantity of vehicles in circulation and, consequently, of the accidents that tend to occur more frequently. Due to the popularization and miniaturization of GPS receivers, the availability of large volumes of data about vehicle speed in urban roads and the large number of traffic-related messages published in social networks, it is now possible to collect enough input data to model traffic conditions based on the observed reduction in speed values. However, it is necessary to filter the data to minimize thematic, spatial and temporal uncertainties. This thesis proposes a methodology to assess the impact of traffic accidents by analyzing speed values. To achieve this goal, it also proposes auxiliary methodologies, aiming at: (1) processing GPS-tracked routes to compute speed statistics and estimate traffic in two-way streets, by performing direction analysis; (2) representing traffic behavior based on the observed speed values; (3) extracting and selecting accident-related data by mining Twitter posts for later identification of the likely effects on speed values. The main contributions of this thesis are: (1) the assessment of traffic conditions based on speed values, which are easier to acquire than data about traffic volume and concentration; (2) the use of posts from social networks, which provide timely access to traffic events; (3) the assessment of urban roads instead of freeways or roads, which require modeling intersections, traffic lights and pedestrian flow; and (4) a methodology designed to extract speed statistics from raw GPS data, which handles likely error sources related to both map matching process and temporal classification.
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ABDULLATIF, AMR RASHAD AHMED. "Unsupervised tracking of time-evolving data streams and an application to short-term urban traffic flow forecasting." Doctoral thesis, Università degli studi di Genova, 2018. http://hdl.handle.net/11567/928997.
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I am indebted to many people for their help and support I receive during my Ph.D. study and research at DIBRIS-University of Genoa. First and foremost, I would like to express my sincere thanks to my supervisors Prof.Dr. Masulli, and Prof.Dr. Rovetta for the invaluable guidance, frequent meetings, and discussions, and the encouragement and support on my way of research. I thanks all the members of the DIBRIS for their support and kindness during my 4 years Ph.D. I would like also to acknowledge the contribution of the projects Piattaforma per la mobilià Urbana con Gestione delle INformazioni da sorgenti eterogenee (PLUG-IN) and COST Action IC1406 High Performance Modelling and Simulation for Big Data Applications (cHiPSet). Last and most importantly, I wish to thanks my family: my wife Shaimaa who stays with me through the joys and pains; my daughter and son whom gives me happiness every-day; and my parents for their constant love and encouragement.
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Gonçalves, Ageitos María. "Assesing variations in urban air quality when introducing on-road traffic management strategies by means of high-resolution modelling: application to Barcelona and Madrid urban areas." Doctoral thesis, Universitat Politècnica de Catalunya, 2009. http://hdl.handle.net/10803/22728.
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La contaminación del aire urbano tiene efectos negativos en la salud humana, los ecosistemas y se asocia con el transporte de contaminantes a larga distancia. La región del sur del Mediterráneo y en concreto la Península Ibérica se ven sometidos frecuentemente a episodios de contaminación fotoquímica. Los niveles de O3 troposférico y, en zonas urbanas, las concentraciones de NO2 y material particulado, superan frecuentemente los niveles establecidos por la legislación europea.
El tráfico rodado constituye la mayor fuente de emisiones antropogénicas en el entorno urbano. Actualmente, se están ensayando distintas alternativas para reducir su contribución. El pronóstico cuantitativo de sus efectos es fundamental y proporciona la base para la toma de decisiones. La herramienta más adecuada para llevar a cabo este tipo de evaluaciones es la modelización atmosférica.
Esta tesis propone el uso del modelo mesoescalar WRF-ARW/HERMES/CMAQ con alta resolución para pronosticar el efecto de distintas estrategias de reducción de emisiones de tráfico. Se centra en las dos mayores ciudades de España: Barcelona y Madrid, representativas de un entorno costero y un entorno continental. Como caso de estudio se ha seleccionado el 17 y 18 de Junio de 2004, que se corresponde simultáneamente con altos niveles de contaminación y con un patrón de circulación de tráfico habitual (días laborables)
Se han seleccionado distintas estrategias realizables a corto plazo, que incluyen: el uso de combustibles alternativos: como gas natural o biodiesel, la introducción de nuevas tecnologías en vehículos, como el uso de vehículos híbridos, o sistemas de planificación urbana, como la introducción de un límite de velocidad. Se han evaluado en términos de cambio de emisiones, consumo de combustible y calidad del aire, no sólo en las zonas urbanas si no a escala regional (en el Noreste y Centro de la Península Ibérica)
Los efectos de dichas estrategias dependen de la zona de aplicación. Los factores principales que condicionan dichas diferencias son: (1) la composición específica de la flota, teniendo la de Barcelona mayor número de vehículos pesados diesel y menor número de turismos que la de Madrid, (2) el peso de los distintos sectores de actividad en el balance de emisiones total, que en Barcelona y el noreste peninsular refleja una mayor actividad industrial frente a Madrid y el centro de la Península, (3) las distintas contribuciones de los procesos atmosféricos a la concentración final de contaminantes, la cuantificación de dichos procesos permite definir patrones de circulación característicos de zonas costeras y con una orografía muy compleja en el área de Barcelona, mientras que en Madrid, el comportamiento es más simple, (4) el régimen de sensibilidad química, que es diferente en ambas ciudades, determina la respuesta del O3 troposférico a la disminución de emisiones de NOx.
El efecto de las estrategias estudiadas es positivo en términos de concentración de NO2, SO2 y PM10, siendo éstas menores que en el escenario base (sin cambios). Sin embargo, el alcance depende en gran medida de las flotas específicas afectadas y del área urbana que se considere. La introducción de vehículos a gas natural constituye una medida eficaz para reducir los niveles de SO2 y PM10 en las ciudades. El uso de biodiesel B20 disminuye fundamentalmente la concentración de SO2, aunque puede conllevar un ligero incremento de concentración de NO2. El uso de vehículos híbridos reduce fundamentalmente las emisiones de NOx, lo que produce una disminución de los niveles de NO2 urbanos. En Madrid este hecho tiene efectos positivos en la concentración de O3 local, sin embargo en Barcelona la disminución de emisiones de NOx supone un incremento del O3 local en todos los casos.
La limitación de velocidad a 80 km h-1 en el área de Barcelona reduce los niveles de NO2 y PM10, sobre todo en las zonas directamente afectadas por la medida. La introducción en el modelo de velocidades de circulación horarias, en lugar de la velocidad constante previamente considerada, ha permitido determinar estos cambios en calidad del aire de manera más precisa, teniendo en cuenta patrones de circulación reales y el efecto de la congestión.
En general las estrategias seleccionadas tienen efectos positivos en zonas a sotavento de las ciudades, incluso en el caso del O3.
La aplicación de modelización atmosférica con alta resolución es una herramienta útil para determinar cuantitativamente los efectos de estrategias de reducción de emisiones de tráfico. Los inventarios de emisiones detallados y la disponibilidad de factores de emisión para nuevas tecnologías o combustibles alternativos son un factor clave para este tipo de desarrollos.The urban air pollution affects human health, causes damage to ecosystems and transboundary air pollution. The southern Mediterranean region and specifically the Iberian Peninsula are commonly affected by highly polluted episodes. The high O3 levels, and specifically the NO2 and PM concentrations in urban areas, are of special concern, frequently exceeding the European air quality targets. On road traffic is the main source of anthropogenic emissions in the urban environment. Different strategies addressed to reduce this contribution are being currently implemented and tested. The quantitative assessment of their effects in advance is fundamental to help decision makers. Air quality modelling is the most suitable tool to perform this kind of evaluations. This PhD Thesis proposes the use of the mesoscalar WRF-ARW/HERMES/CMAQ modelling system with high resolution to test in advance such strategies for on-road traffic emissions abatement. It focuses on the two most populated urban areas of Spain, Barcelona and Madrid, which constitute a typically coastal and continental environment. The 17-18 June, 2004 is chosen as the study case. It fits in a poor air quality situation in both areas but also in an usual traffic circulation pattern (working days). Several feasible short-term strategies are selected and implemented in the emission model in the most realistic way as possible. They include: use of alternative fuels, such as natural gas or biodiesel, introduction of new technologies, such as hybrid electric vehicles, and urban management schemes, such as speed circulation limit. They are evaluated in terms of emissions, fuel consumption and air quality changes in the urban areas and at a regional scale, over the North-eastern and Central Iberian Peninsula. The effects of these strategies depend on the study areas. The factors that condition these differences are mainly: (1) the specific vehicle fleet composition, having Barcelona a larger proportion of diesel and commercial vehicles and lower quantity of passenger cars than Madrid; (2) the different contributions of the activity sectors to anthropogenic emissions, which in Barcelona and the North-eastern Iberian Peninsula reflect a heavier industrial activity against Madrid and the Central Iberian Peninsula region; (3) the different contributions of atmospheric processes leading to the concentration of pollutants; their quantification leads to the observance of characteristic transport patterns of a coastal area and very complex terrains in Barcelona, and a much simpler behaviour in Madrid, a typically continental area; (4) the chemical sensitivity regime also differs, which particularly affects the O3 response to NOx abatement strategies. The effect of all the tested strategies in urban NO2, SO2 and PM10 concentrations is positive, being lower than in the base case. Nevertheless the extent of this effect largely depends on the affected fleets and on the urban area of application. The introduction of natural gas vehicles proved to be specifically effective in reducing SO2 and PM10 concentrations in Barcelona and Madrid areas. The introduction of biodiesel as a fuel would slightly affect the urban air quality levels, improving mainly the SO2 levels. The use of hybrid cars affects the NOx emissions considerably, reducing NO2 urban levels. Moreover in Madrid it causes a noticeable reduction in the local O3 concentrations. The Barcelona photochemical regime involves local O3 concentrations increase when reducing NOx emissions. The introduction of an 80 km h-1 speed limit in the Barcelona area reduces NO2 and PM10 levels, specifically in the zones affected by the measure. The inclusion in the model of hourly speed data from measurement campaigns instead of the previously constant speed considered, allowed assessing the gains of such a measure in a more realistic manner, taking into account real circulation patterns and the congestion effect. The effects of the selected strategies are always positive in downwind areas, even in terms of O3 concentration. The application of high resolution modelling proved to be a useful tool to quantitatively asses the effect of management strategies. The detailed emissions inventories and the availability of emission factors for new technology vehicles or alternative fuels are key factors to this kind of developments.
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Castrillon, Felipe. "Theoretical analysis of the effects of bus operations on urban corridors and networks." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54349.
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Bus systems have a large passenger capacity when compared to personal vehicles and thus have the potential to improve urban mobility. However, buses that operate in mixed vehicle traffic can undermine the effectiveness of the road system as they travel at lower speeds, take longer to accelerate and stop frequently to board and alight passengers. In traffic flow theory, buses are known as slow-moving bottlenecks that have the potential to create queue-spillbacks and thus increase the probability of gridlock. Currently, traditional metropolitan transportation planning models do not account for these negative effects on roadway capacity. Also, research methods that study multimodal operations are often simulated or algorithmic which can only provide specific results for defined inputs.
The objective of this research is to model and understand the effects of bus operations (e.g., headway, number of stops, number of routes) on system performance (e.g. urban corridor and network vehicular capacity) using a parsimonious analytical approach with a few parameters.The models are built using the Macroscopic Fundamental Diagram (MFD) of traffic which provides aggregate measures of vehicle density and flow. Existing MFD theory, which accounts for corridors with only one vehicle class are extended to include network roadway systems and bus operations. The results indicate that buses have two major effects on corridors: the moving bottleneck and the bus short-block effect. Also, these corridor effects are expanded to urban networks through a vehicle density-weighted average. The models have the potential to transform urban multimodal operations and management as they provide a simple tool to capture aggregate performance of transportation systems.
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Patterson, Joanne Louise. "Urban scale modelling of traffic and cycling flow using spatial analysis and an assessment of factors that influence cyclist behaviour." Thesis, Cardiff University, 2014. http://orca.cf.ac.uk/66970/.
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To understand and facilitate modal shift to more sustainable modes of transport there is a need to model accessibility and connectivity at an urban scale using data collection and modelling procedures that require less data and specialist input than traditional transport models. This research has used spatial analysis modelling procedures based on space syntax to investigate the potential to model aggregate traffic flows at an urban scale, and to investigate the potential to apply the same methodology to model both aggregate and individual cycle flows. Cyclist behaviour has been investigated through a questionnaire to support modelling work. The research has demonstrated that spatial analysis modelling is an effective means of representing urban scale motor traffic network, however, modifications to the model were required to achieve a correlation between modelled and measured motor traffic flow comparable to other modelling procedures. Boundary weighting was found to be effective at representing traffic crossing the boundary of an isolated urban sub-area, but was not so effective at an urban scale. Road weighting was found to be effective in improving model performance by representing traffic flows along routes according to a national classification scheme. It was demonstrated that these modelling principles could be used to represent an urban bicycle network and that the impact of the modification of infrastructure on relative flows of both cyclists and motor traffic could be accommodated. The modelling approach has the potential to be extremely useful at an early planning stage to represent changes to flows across the network. A survey of behaviour identified that cyclists modify their journey to use cycling facilities such as on-road lanes and off-road paths, or to avoid particular areas perceived to be less favourable for cyclists and that analysis indicates that it is difficult to predict (25% from survey) individual route choice. Results indicate that there were more opportunities related to route characteristics that could be influenced by infrastructure changes for occasional cyclists than for frequent/everyday cyclists.
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Roll, Josh Frank. "Bicycle Traffic Count Factoring: An Examination of National, State and Locally Derived Daily Extrapolation Factors." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/998.
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Since nearly the beginning of the wide spread adoption of the automobile, motorized traffic data collection has occurred so that decision makers have information to plan the transportation system. Widespread motorized traffic data collection has allowed for estimating traffic volumes using developed extrapolation methods whereby short-term counts in sample locations can be expanded to longer periods. As states and local planning agencies make investments in bicycle infrastructure and count programs develop, similar extrapolation methods will be needed. The only available guidance on extrapolating bicycle counts comes from the National Bicycle and Pedestrian Documentation Project (NBPDP), yet no validation of these factors have been done to assess their usability in specific area. Using bicycle traffic count data from the Central Lane Metropolitan Planning Organization Count Program in Oregon, this research demonstrates that using study area data to generate time-of-day factors produces results with less error compared to application of the NBPDP time-of-day factors. Factors are generated in two separate way in order to reduce error from estimating daily bicycle volumes. Factors groups are developed using bicycle facility type where counts are collected. This research also seeks to add to the literature concerning bicycle travel patterns by using study area data to establish a university travel pattern exemplified by a flat hourly distribution from morning to evening.
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Wu, Jiechen. "Systems Perspectives on Modelling and Managing Future Anthropogenic Emissions in Urban Areas : Nitrogen, Phosphorus and Carbon Studies in Stockholm, Sweden." Doctoral thesis, KTH, Industriell ekologi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-186245.
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Managing anthropogenic emissions in urban areas is a major challenge in sustainable environmental development for cities, and future changes and increasing urbanisation may increase this challenge. Systems perspectives have become increasingly important in helping urban managers understand how different changes may alter future emissions and whether current management strategies can efficiently manage these emissions. This thesis provides some systems perspectives that have been lacking in previous studies on modelling and managing future anthropogenic emissions in urban areas. The city of Stockholm, Sweden, was selected as the study site and studies about nitrogen, phosphorus and carbon were chosen, given world-wide urban eutrophication and global concerns about climate change. A substance flow analysis (SFA) structured model, comprising a source model coupled with a watershed model in an SFA structure, was developed to investigate future nutrient loading scenarios under various urban changes in small urban lake catchments. The results demonstrated that climate change potentially posed a greater threat to future nutrient loads to a selected lake catchment in Stockholm than the other scenarios examined. Another SFA-based study on future phosphorus flows through the city of Stockholm indicated that the best management option may depend on the perspective applied when comparing future scenarios of phosphorus flows and that both upstream and downstream measures need to be considered in managing urban phosphorus flows. An evaluation approach for examining current management plans and low-carbon city initiatives using the Driving forces-Pressure-States-Impact-Response (DPSIR) framework, was formulated. With such an evaluation approach, investigation of how well selected plans cover different aspects of the DPSIR framework and whether root causes and systematic measures are highlighted is possible. The results revealed that the current low-carbon city initiative in Stockholm falls within pressure-based, driver-orientated plans and that technical, institutional and cognitional measures are generally well covered.QC 20160510
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Kamiyama, Naoyuki. "Studies on Quickest Flow Problems in Dynamic Networks and Arborescence Problems in Directed GraphsA Theoretical Approach to Evacuation Planning in Urban Areas." 京都大学 (Kyoto University), 2009. http://hdl.handle.net/2433/124512.
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Papageorgiou, Asterios. "A physical accounting model for monitoring material flows in urban areas with application to the Stockholm Royal Seaport district." Thesis, KTH, Hållbar utveckling, miljövetenskap och teknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-231160.
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There is a plethora of methods and tools that can be used for the assessment of Urban Metabolism. Nevertheless, there is no standardized method for accounting of material flows within and across the boundaries of urban systems. This thesis aims to provide a physical accounting model for monitoring material flows in urban areas that could potentially become the basis for the development of a standardized accounting method in the long term. The model is based on a Physical Input Output Table framework and builds upon the strengths of existing accounting methods but at the same time it demonstrates new features that can address their limitations. The functions of the model were explored and evaluated through its application to an urban neighbourhood in the Stockholm Royal Seaport. Bottom-up data were used for the application of the model in the case study. The application of the model provided a preliminary description of the material flows in the neighbourhood and most importantly provided information that underpinned the assessment of the strengths and limitations of the model. It was deduced, that on the one hand the model can describe successfully the physical interactions between the urban socioeconomic system and the environment or other socioeconomic systems and at the same it has the potentials to illustrate the intersectoral flows within the boundaries of the system. In addition, it can be used to structure available data on material flows and promote the study of an urban system with a life cycle perspective. On the other hand, the process of compiling the tables of the model can be considered as complex and moreover the data requirements for the compilation of the tables are significant. Especially, the compilation of the tables of the model with bottom-up data may require a laborious data collection and analysis process, which however may not address all data gaps. Thus, the combination of bottom-up data with top-down data is recommended. Moreover, it is recommended the development of integrated databases for data collection and management at the municipal level and the fostering of collaboration between stakeholders within the municipalities to facilitate dissemination of data and information.Mer än hälften av den globala befolkningen bor numera i urbana områden och denna andel uppskattas öka under de kommande årtiondena. Urbana system förbrukar fysiska resurser och genererar stora mängder av rester vilket innebär påfrestningar på miljön samt hindrar en hållbar utveckling. Således kan förståelse av Urban Metabolism (UM) stödja insatserna för att effektivisera resursförbrukningen och avfallshanteringen. I detta sammanhang har en stor mängd av metoder och verktyg utvecklats och tillämpats i UM-studier, såsom Materialflödeanalys (Material Flow Analysis - MFA) och Input-output Analys (Input Output - IOA) baserat på fysiska input-output tabeller (Input Output Tables – PIOTs). Ändå saknas en standardiserad metod för redovisning av materialflöden inom och över gränserna av urbana system. I samband med detta examensarbete utvecklades en fysisk räkenskapsmodell för övervakning av materialflöden i urbana områden. Denna modell kan potentiellt bli grunden för en enhetlig metod för beräkning av materialflöden i urbana system. Modellen utvecklades i en stegvis process och baserades på litteraturgranskning. Grunden för modellen är ett omfattande PIOT ramverk som kan användas för registrering av materialflöden i urbana system. PIOT ramverket är annorlunda än de typiska PIOT-systemen. Det ger en tydligare avgränsning av systemgränserna, det visar tydligt ursprung och destination för materialflöden, och dessutom kan det erbjuda ett livscykelperspektiv på materialflödena. Modellen består av en uppsättning identiska PIOT. Varje deltabell innehåller materialflöden som tillhör i en specifik klass, medan huvudtabellen aggregerar materialet som strömmar för alla material från deltabellerna. Därigenom kan modellen avbilda materialflödena i ett aggregat-perspektiv och samtidigt ge fysiska räkenskaper för specifika materialtyper. Modellen användes i en nybyggd stadsdel i Norra Djurgårdsstaden (NDS), för att utforska och bedöma dess funktioner. För att kartlägga och kvantifiera flödena i stadsdelen genomfördes en MFA baserad på “bottom-up-data”. Insamlingen och analysen av data var emellertid en besvärlig process och dessutom kunde flera materialflöden inte kvantifieras på grund av databrister. Därför kunde modellens tabeller inte fyllas fullständigt och ett flödesdiagram skapades med både kvantitativa och kvalitativa flöden. Trots att det fanns databrister lyckades tillämpningen av modellen att avbilda UM i det avgränsade urbana systemet på ett adekvat sätt. Det visade tydligt att nästan 96% av de materiella insatserna är ackumulerade i lager. Dessutom fastställde modellen kvalitativt den fysiska växelverkan mellan det urbana systemet och den naturliga miljön, det nationella socioekonomiska och det globala socioekonomiska systemet. Emellertid var det inte möjligt att bedöma modellens fullständiga potential eftersom det inte var möjligt att upprätta intersektorala kopplingar. Dessutom beräknades indirekta flöden av flera importerade material baserat på koefficienterna för materialintensitet. Detta tillvägagångssätt kan erbjuda insikt om de uppströms påfrestningar som orsakas av materialproduktionen. Dock finns det endast koefficienter för specifika material. Därför kan de inte användas för att uppskatta de indirekta flödena för varje materialinflöde. Dock framhöll deras partiella tillämpning att indirekta flödena var 38% högre än direktflödena, vilket indikerar att påfrestningar som utövas till miljön på grund av produktion av importerade material är betydande. Tillämpningen av modellen möjliggjorde en bedömning av både styrkor och svagheter hos modellen. Å ena sidan kan modellen fastställa fysiska interaktioner mellan det urbana socioekonomiska systemet och naturmiljön, det nationella socioekonomiska systemet och det globala socioekonomiska systemet. Dessutom har det potential att beskriva intersektorala flöden inom gränserna för det urbana systemet och det kan erbjuda insikt om materialinflödenas ursprung och materialutflödenas destination. En annan styrka i modellen är att den erbjuder livscykelperspektiv genom att ta hänsyn till indirekta flöden av importerade material. Å andra sidan demonstrerades att sammanställningenav modellens tabeller kräver en stor mängd data, speciellt när data erhålls med ett ”bottom-up” tillvägagångssätt. Ändå är bottom-up data inte alltid tillgängliga för urbana områden. En annan svaghet är att sammanställningenav tabellerna i modellen med bottom-up-data kräver en mödosam process för datainsamling och analys. Dessutom kräver analysen av data många antaganden som ökar osäkerheten i resultaten. Ovanstående svagheter i modellen kan hindra tillämpningen av modellen för räkenskap av materialflöden på urbana områden. Således rekommenderas kombinationen av bottom-up-data med top-down data för tillämpning av modellen. Dessutom föreslås utvecklingen av integrerade databaser för datainsamling om materialflöden i urbana områden.
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Thomas, Noura. "Analysis of right-turn lane length in left-hand traffic countries at signalised intersections of urban roads." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2016. https://ro.ecu.edu.au/theses/1781.
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Analysis of the right turn lane length of urban roads in left-hand traffic countries, such as Australia, UK and India (left-turn lane length in right-hand traffic countries such as USA), at signalised intersections encounters two main geometric features namely, deceleration length and storage length. The literature shows that in routine practice, the deceleration length is generally estimated by using constant deceleration rate. Many researchers consider this assumption for all design speeds unrealistic as it does not reflect the influence of the pavement condition. Hence, it may be desirable to consider the pavement’s condition in terms of its longitudinal coefficient of friction in the design analysis. In regard to the storage length, a large number of the current guidelines and models estimate the storage length of right-turn lane at signalised intersections under split phase. Hence, there is a need to examine other phase types and timings and integrate the signal timing as a part of the geometric design
In this thesis, two analytical expressions have been analysed for the design of deceleration length. The first expression assumes a constant deceleration rate, and the second expression employs the concept of forces on a rotating wheel in which the coefficient of longitudinal friction between a vehicle’s tyres and the road surface is considered. The calculated deceleration lengths by these two expressions were compared with the recommended values in American and Australian standards as well as with the deceleration lengths that were obtained by a recent simulation study presented in the literature. It has been found that applying a constant deceleration rate of 2.74 m/s2 in the first expression provides the values of deceleration length comparable to most guidelines and studies. The second expression highlights the importance of using the pavement design in terms of the coefficient of friction to reduce the deceleration length in the case of limited space.
A MATLAB based simulation programme has been developed to provide an estimate of the right-turn lane storage length for different traffic volumes in order to avoid the problems associated with blocking and overflow of right turn vehicles in 95% of cycles. In established intersections that cannot be modified due to physical constraints, the model is flexible enough to examine different signal phase types and timings and provides other solutions to reduce overflow and/or blockage situations. The simulation model also takes into consideration the leftover queue. The model results have been compared against an available analytical method in which similar signal phases and timings were investigated. The outcomes are similar to those of the analytical model in most of the signal phase types. The simulation model provides the flexibility to estimate the right-turn lane length for different combinations of through lane and right-turn lane traffic volumes.
The developed simulation model has also been validated against the field data using three parameters, namely 95th percentile of maximum queue, overflow cycle percentage, and blockage cycle percentage. Comparing with the field observations yields a level of accuracy in the range of 78%-85%. Finally this simulation model has been used to optimise the green time in the case of split phase that demonstrates a large difference in traffic volumes of two opposite approaches; this could reduce the mean wait time by up to 28%.
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Lackey, Nathan. "Simulating Autonomous Vehicles in a Microscopic Traffic Simulator to Investigate the Effects of Autonomous Vehicles on Roadway Mobility." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555072367385629.
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Stange, Vanessa Verfasser], Mark [Akademischer Betreuer] [Vollrath, Simone [Akademischer Betreuer] Kauffeld, and Josef F. [Akademischer Betreuer] Krems. "Human driver and passenger reaction to highly automated vehicles in mixed traffic on highways and in urban areas / Vanessa Stange ; Mark Vollrath, Simone Kauffeld, Josef F. Krems." Braunschweig : Technische Universität Braunschweig, 2021. http://d-nb.info/1237047730/34.
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Johnson, Pamela Christine. "Bicycle Level of Service: Where are the Gaps in Bicycle Flow Measures?" PDXScholar, 2014. https://pdxscholar.library.pdx.edu/open_access_etds/1975.
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Bicycle use is increasing in many parts of the U.S. Local and regional governments have set ambitious bicycle mode share goals as part of their strategy to curb greenhouse gas emissions and relieve traffic congestion. In particular, Portland, Oregon has set a 25% mode share goal for 2030 (PBOT 2010). Currently bicycle mode share in Portland is 6.1% of all trips. Other cities and regional planning organizations are also setting ambitious bicycle mode share goals and increasing bicycle facilities and programs to encourage bicycling. Increases in bicycle mode share are being encouraged to increase. However, cities with higher-than-average bicycle mode share are beginning to experience locations with bicycle traffic congestion, especially during peak commute hours. Today, there are no established methods are used to describe or measure bicycle traffic flows.
In the 1960s, the Highway Capacity Manual (HCM) introduced Level of Service (LOS) measurements to describe traffic flow and capacity of motor vehicles on highways using an A-to-F grading system; "A" describes free flow traffic with no maneuvering constraints for the driver and an "F" grade corresponds to over capacity situations in which traffic flow breaks down or becomes "jammed". LOS metrics were expanded to highway and road facilities, operations and design. In the 1990s, the HCM introduced LOS measurements for transit, pedestrians, and bicycles. Today, there are many well established and emerging bicycle level of service (BLOS) methods that measure the stress, comfort and perception of safety of bicycle facilities. However, it was been assumed that bicycle traffic volumes are low and do not warrant the use of a LOS measure for bicycle capacity and traffic flow. There are few BLOS methods that take bicycle flow into consideration, except for in the case of separated bicycle and bicycle-pedestrian paths.
This thesis investigated the state of BLOS capacity methods that use bicycle volumes as a variable. The existing methods were applied to bicycle facility elements along a corridor that experiences high bicycle volumes in Portland, Oregon. Using data from the study corridor, BLOS was calculated and a sensitivity analysis was applied to each of the methods to determine how sensitive the models are to each of the variables used. An intercept survey was conducted to compare the BLOS capacity scores calculated for the corridor with the users' perception. In addition, 2030 bicycle mode share for the study corridor was estimated and the implications of increased future bicycle congestion were discussed. Gaps in the BLOS methods, limitations of the thesis study and future research were summarized.
In general, the existing methods for BLOS capacity are intended for separated paths; they are not appropriate for existing high traffic flow facilities. Most of the BLOS traffic flow methods that have been developed are most sensitive to bicycle volumes. Some of these models may be a good starting point to improve BLOS capacity and traffic flow measures for high bicycle volume locations. Without the tools to measure and evaluate the patterns of bicycle capacity and traffic flow, it will be difficult to monitor and mitigate bicycle congestion and to plan for efficient bicycle facilities in the future. This report concludes that it is now time to develop new BLOS capacity measures that address bicycle traffic flow.
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Unell, Mathias, and Natalie Ruuska. "Gatuutformning med autonoma fordon. : En undersökning över möjliga förändringar i Stockholm." Thesis, KTH, Byggteknik och design, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-259713.
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Utvecklingen med automatiserade funktioner i fordon går framåt och i framtiden är det möjligt att bilen är helt självkörande. Stockholm växer och även trafiken vilket medför utmaningar att lösa som exempelvis att öka framkomligheten, tillgänglighet och hållbarhet. Därför har Stockholms stad tagit fram mål för tydliggöra vad det framtida gaturummen ska uppfylla. Syftet med denna rapport var att sammanställa information om hur autonoma fordon kan påverka gatuutformningen samt jämföra resultatet med målen om gatuplanering i Stockholms stad. Resultatet visade att autonoma fordon kan möjliggöra en ökad delningsekonomi inom transportsystemet där allt färre människor äger ett eget fordon. I stället kan fordonen ingå i nya mobilitetslösningar. Detta kan medföra en förbättrad markanvändning och nya möjligheter till hur vi använder gaturummen. Exempelvis nämns gaturummet kunna stängas av för trafik efter rusningstid och ge plats för andra aktiviteter. Resultatet visade även att fordonenen har behov för mer integrerad teknik i gaturummen samt krav på högre läsbarhet av linjemarkeringar och vägmärken. En slutsats som kunde dras var att många utav Stockholms stads mål kan uppnås, exempelvis miljömål, mindre trängsel och högre trafiksäkerhet. Av resultatet framgår det att de två viktigaste faktorerna är den politiska och tekniska utveckling kring autonoma fordon.The development with automated functions in vehicles is moving forward and in the future it is possible that cars is completely self-driving. Stockholm is growing and also the traffic, which poses challenges to solve, such as increasing accessibility, availability and sustainability. Therefore, the City of Stockholm has developed goals for clarifying what the future street areas should fulfill. The purpose of this report was to compile information on how autonomous vehicles can influence street design and compare the results with the goals of street planning in the City of Stockholm. The result showed that autonomous vehicles can enable an increased sharing economy within the transport system, which means that fewer people own their own vehicle. Instead, the vehicles can be included in new mobility solutions. This can lead to improved land use and new opportunities for how we use the street space. For example, the street room is mentioned as being able to be switched off for traffic after rush hour and providing space for other activities. The results also showed that the vehicles need more integrated technology in the street space and requirements for higher readability of line markings and road signs. One conclusion was that many of Stockholm's goals can be achieved, such as environmental goals, less congestion and higher road safety. The result shows that the two most important factors are the political and technical development of autonomous vehicles.
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Pezo, Silvano Ary. "Advancing Traffic Safety : An evaluation of speed limits, vehicle-bicycle interactions, and I2V systems." Doctoral thesis, KTH, Transportvetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-195640.
Full textAbstract:
Since the introduction of motor vehicles, the number of fatalities and accidents has been a concern for society.The number of fatalities on roads is amongst the most common causes of mortality worldwide (WHO, 2015).Even in industrialized countries the number of fatalities remains unacceptable. Therefore, in the last decades, anumber of approaches have emerged to support and boost traffic safety towards a system free from fatalities andserious impairment outcomes. ‘Sustainable Safety’ and ‘Vision Zero’ are well-known examples aiming to avoidfatalities within the traffic system and reduce injury severity when a traffic accident is inevitable. However, thenumber of fatalities and seriously injured accidents are still relatively high. More specifically, vulnerable roadusers remain involved in fatal and serious accidents even in industrialized countries. Therefore, further advancesin traffic safety studies are needed. This thesis aims at evaluating the impact of road characteristics, traffic rulesand information provision towards a safer traffic system. The thesis is composed of five scientific papers whichsummarizes the main contributions of this work.QC 20161109