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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

The economic rationale for stochastic urban transport models and travel behaviour : a mathematical programming approach to quantitative analysis with Perth data

Ernst, Wolfgang F. January 2003 (has links)
[Formulae and special characters can only be approximated here. Please see the pdf version of the abstract for an accurate reproduction.] This thesis reviews, extends and applies to urban traffic analysis the entropy concept of Shannon and Luce's mathematical psychology in a fairly complex and mathematically demanding model of human decision making, if it is solved as a deeply nested structure of logit calculus. Recognising consumers' different preferences and the universal propensity to seek the best choice when going to some desired goal (k), a transparent mathematical program (MP) is developed: the equivalent of a nested multinomial logit model without its inherent computational difficulty. The MP model makes a statistical assessment of individual decisions based on a randomised (measurable) utility within a given choice structure: some path through a diagram (Rk, Dk), designed a priori, of a finite number of sequential choices. The Equivalence Theorem (ET) formalises the process and states a non-linear MP with linear constraints that maximises collective satisfaction: utility plus weighted entropy, where the weight (1/θn) is a behavioural parameter to be calibrated in each case, eg for the Perth CBD. An optimisation subject to feasible routes through the (Rk, Dk) network thus captures the rational behaviour of consumers on their individually different best-choice decision paths towards their respective goals (k). This theory has been applied to urban traffic assignment before: a Stochastic User Equi-librium (SUE). What sets this thesis apart is its focus on MP models that can be solved with standard Operations Research software (eg MINOS), models for which the ET is a conditio sine qua non. A brief list of SUE examples in the literature includes Fisk's logit SUE model in (impractically many) route flows. Dial's STOCH algorithm obviates path enumeration, yet is a logit multi-path assignment procedure, not an MP model; it is nei-ther destination oriented nor an optimisation towards a SUE. A revision of Dial's method is provided, named STOCH[k], that computes primal variables (node and link flows) and Lagrangian duals (the satisfaction difference n→k). Sheffi & Powell presented an unconstrained optimisation problem, but favoured a probit SUE, defying closed formulae and standard OR software. Their model corresponds to the (constrained) dual model here, yet the specifics of our primary MP model and its dual are possible only if one restricts himself to logit SUE models, including the ET, which is logit-specific. A real world application needs decomposition, and the Perth CBD example is iteratively solved by Partial Linearisation, switching from (measured) disutility minimisation to Sheffi & Powell's Method of Successive Averages near the optimum. The methodology is demonstrated on the Perth Central Business District (CBD). To that end, parameter Θ is calibrated on Main Roads' traffic count data over the years 1997/98 and 1998/99. The method is a revision of Liu & Fricker's simultaneous estimation of not only Θ but an appropriate trip matrix also. Our method handles the more difficult variable costs (congestion), incomplete data (missing observations) and observation errors (wrong data). Finally, again based on Main Roads' data (a sub-area trip matrix), a Perth CBD traffic assignment is computed, (a) as a logit SUE and - for comparison - (b) as a DUE (using the PARTAN method of Florian, Guélat and Spiess). The results are only superficially similar. In conclusion, the methodology has the potential to replace current DUE models and to deepen transport policy analysis, taking into account individual behaviour and a money-metric utility that quantifies 'social benefits', for instance in a cost-benefit-analysis.
62

A model for the economic analysis of road projects in an urban network with interrelated incremental traffic assignment method

Lloyd, Evan Robert January 2005 (has links)
[Truncated abstract] In an urban network, any change to the capacity of a road or an intersection will generally result in some traffic changing its route. In addition the presence of intersections creates the need for frequent stops. These stops increase the fuel consumption by anywhere between thirty to fifty percent as evidenced by published standardised vehicle fuel consumption figures for urban and for country driving. Other components of vehicle operating costs such as tyre and brake wear and time costs will also be increased by varying amounts. Yet almost all methods in use for economic evaluation of urban road projects use open road vehicle operating costs (sometimes factored to represent an average allowance for stopping at intersections) for one year or sometimes two years in the analysis period and then make assumptions about how the year by year road user benefits may change throughout the period in order to complete the analysis. This thesis will describe a system for estimating road user costs in an urban network that calculates intersection effects separately and then adds these effects to the travel costs of moving between intersections. Daily traffic estimates are used with a distribution of the flow rate throughout the twenty-four hours giving variable speed of travel according to the level of congestion at different times of the day. For each link, estimates of traffic flow at two points in time are used to estimate the year-by-year traffic flow throughout the analysis period by linear interpolation or extrapolation. The annual road user costs are then calculated from these estimates. Annual road user benefits are obtained by subtracting the annual road user costs for a modified network from the annual road user costs for an unmodified network. The change in the road network maintenance costs are estimated by applying an annual per lane maintenance cost to the change in lane-kilometres of road in the two networks. The Benefit Cost Ratio is calculated for three discount rates. An estimate of the likely range of error in the Benefit Cost Ratio is also calculated
63

Διερεύνηση βελτιωμένων τεχνικών εφαρμογής του μοντέλου κυκλοφοριακού σχεδιασμού SATURN

Κρητικού, Σμαράγδα 06 December 2013 (has links)
Αντικείμενο της παρούσας μεταπτυχιακής εργασίας είναι η διερεύνηση βελτιωμένων τεχνικών εφαρμογής του μοντέλου κυκλοφοριακού σχεδιασμού SATURN. Για το σκοπό αυτό επιλέγονται να μελετηθούν δύο διαφορετικές περιοχές στην υφιστάμενη και σε μία νέα κατάσταση. Συγκεκριμένα, η πρώτη περιοχή μελετάται ως ρυθμιστικό δίκτυο και οι αλλαγές στη νέα της κατάσταση αφορούν αλλαγή λειτουργίας κάποιων υφιστάμενων οδών όπως είναι αλλαγή κατεύθυνσης ροής οχημάτων και οι μονοδρομήσεις, και η δεύτερη ως προσομοίωσης και οι αλλαγές στη νέα της κατάστασης αφορούν την πεζοδρόμηση μίας οδού. Τα δίκτυα αυτά μελετώνται και ως ντετερμινιστικά και ως στοχαστικά με τη χρήση του αλγόριθμου Frank & Wolf και του Burrell αντίστοιχα, αλγόριθμους που διατίθενται μέσω του SATURN. Από την ανάλυση των αποτελεσμάτων παρατηρείται ότι οι αλλαγές που εφαρμόστηκαν στα δύο δίκτυα της παρούσας εργασίας φορτίζουν τα δίκτυο περισσότερο με αποτέλεσμα να επιβαρύνουν την κυκλοφοριακή κατάσταση. Επιπλέον διαπιστώθηκε ότι οσο πιο απλό είναι ένα δίκτυο τόσο πιο εύκολη είναι η επιλογή της συντομότερης διαδρομής από τους χρήστες, ενώ όσο πληθαίνουν οι εναλλακτικές διαδρομές παρατηρούνται διαφορές στην κατανομή των φόρτων σε αυτές και στην επίλυση του προβλήματος καταμερισμού, καθώς επίσης και ότι σε περιπτώσεις όπου οι εναλλακτικές διαδρομές καθίστανται ανταγωνιστικές παρατηρείται διασπορά των μετακινούμενων σε αυτές. Επιπροσθέτως ενδείκνυται το στοχαστικό μοντέλο ως καταλληλότερο και στις δύο εφαρμογές. Τέλος τo SATURN αποτελεί ένα χρήσιμο προγράμματα ανάλυσης δικτύων, προσομοίωσης και κατανομής της κυκλοφορίας. / The subject of this thesis is the investigation of improved application techniques of model transport planning SATURN. For this purpose, two different networks were chosen to study in two situations, one in an existing and one in a new situation . Specifically , the first area is being studied as a buffer network. The changes in the new situation are changes as the flow direction of vehicles and one-way. The second area is being studies as simulation network. In the new situation one street become way for pedestrian. These networks are studied as deterministic and stochastic using the algorithm Frank & Wolf and Burrell respectively, these algorithms are available through the SATURN. After the analysis of the results, it is observed that changes implemented in both networks affect in a worse way the traffic situation. In addition it was found that the simpler is a network the easier is to select the shortest route from the users. Opposed to this, increasing the alternative routes observed differences in the distribution of flows in them and in the assignment problem’s solution. Moreover in cases where alternative routes become competitive, dispersion of traveling is observed in them. Additionally stochastic model is showed to be appropriate in both applications . Finally to SATURN is a useful network analysis programs of simulation and assignment of traffic to urban road networks.
64

INTEGRATION OF THE REGRESSION-BASED LAND USE MODEL AND THE COMBINED TRIP DISTRIBUTION-ASSIGNMENT TRANSPORTATION MODEL

An, Meiwu 01 January 2010 (has links)
Regional growth caused the emergence of traffic congestion and pollution in the past few decades, which have started to affect small urban areas. These problems are not only related to transportation system design but also to land use planning. There has been growing recognition that the relationship between land use and transportation needs to be understood and analyzed in a consistent and systematic way. Integrated urban models have recently been introduced and implemented in several metropolitan areas to systematically examine the relationship between land use and transportation. The general consensus in the field of integrated urban models is that each model has its own limitations and assumptions because they are each designed for different application purposes. This dissertation proposes a new type of methodology to integrate the regression-based land use model and the combined trip distribution-assignment transportation model that can be applied to both metropolitan areas and small urban areas. The proposed integrated land use and transportation model framework has three components: the regression-based land use model, the combined trip distributionassignment transportation model, and the interaction between these two models. The combined trip distribution-assignment model framework provides the platform to simultaneously integrate the transportation model with the land use model. The land use model is developed using an easy-to-implement method in terms of correlation and regression analysis. The interaction between the land use model and the transportation model is examined by two model frameworks: feedback model framework and simultaneous model framework. The feedback model framework solves the land use model and the transportation model iteratively. The simultaneous model framework brings the land use model and the transportation models into one optimization program after introducing the used path set. Both the feedback model and the simultaneous model can be solved to estimate link flow, origin-destination (OD) trips, and household distribution with the results satisfying network equilibrium conditions. The proposed integrated model framework has an “affordable and easy-toimplement” land use model; it can be performed in small urban areas with limited resources. The model applications show that using the proposed integrated model framework can help decision-makers and planners in preparing for the future of their communities.
65

Modelling and Appraisal in Congested Transport Networks

West, Jens January 2016 (has links)
Appraisal methodologies for congestion mitigation projects are relatively less well developed compared to methodologies for projects reducing free flow travel times. For instance, static assignment models are incapable of representing the build-up and dissipation of traffic queues, or capturing the experienced crowding caused by uneven on-board passenger loads. Despite the availability of dynamic traffic assignment, only few model systems have been developed for cost-benefit analysis of real applications. The six included papers present approaches and tools for analysing traffic and transit projects where congestion relief is the main target. In the transit case studies, we use an agent-based simulation model to analyse congestion and crowding effects and to conduct cost-benefit analyses. In the case study of a metro extension in Stockholm, we demonstrate that congestion and crowding effects constitute more than a third of the total benefits and that a conventional static model underestimates these effects vastly. In another case study, we analyse various operational measures and find that the three main measures (boarding through all doors, headway-based holding and bus lanes) had an overall positive impact on service performance and that synergetic effects exist. For the congestion charging system in Gothenburg, we demonstrate that a hierarchal route choice model with a continuous value of time distribution gives realistic predictions of route choice effects although the assignment is static. We use the model to show that the net social benefit of the charging system in Gothenburg is positive, but that low income groups pay a larger share of their income than high income groups. To analyse congestion charges in Stockholm however, integration of dynamic traffic assignment with the demand model is necessary, and we demonstrate that this is fully possible. Models able to correctly predict these effects highlight the surprisingly large travel time savings of pricing policies and small operational measures. These measures are cheap compared to investments in new infrastructure and their implementation can therefore lead to large societal gains. / <p>QC 20160829</p>
66

Development of a behaviorally induced system optimal travel demand management system

Hu, Xianbiao, Chiu, Yi-Chang, Shelton, Jeff 30 March 2016 (has links)
The basic design concept of most advanced traveler information systems (ATIS) is to present generic information to travelers, leaving travelers to react to the information in their own way. This passive way of managing traffic by providing generic traffic information makes it difficult to predict the outcome and may even incur an adverse effect, such as overreaction (also referred to as the herding effect). Active traffic and demand management (ATDM) is another approach that has received continual attention from both academic research and real-world practice, aiming to effectively influence people's travel demand, provide more travel options, coordinate between travelers, and reduce the need for travel. The research discussed in this article deals with how to provide users with a travel option that aims to minimize the marginal system impact that results from this routing. The goal of this research is to take better advantage of the available real-time traffic information provided by ATIS, to further improve the system level traffic condition from User Equilibrium (UE), or a real-world traffic system that is worse than UE, toward System Optimal (SO), and avoid passively managing traffic. A behaviorally induced, system optimal travel demand management model is presented to achieve this goal through incremental routing. Both analytical derivation and numerical analysis have been conducted on Tucson network in Arizona, as well as on the Capital Area Metropolitan Planning Organization (CAMPO) network in Austin, TX. The outcomes of both studies show that our proposed modeling framework is promising for improving network traffic conditions toward SO, and results in substantial economic savings.
67

Application of GPU Computing to Some Urban Traffic Problems

Jradi, Walid Abdala Rfaei 30 November 2016 (has links)
Submitted by Erika Demachki (erikademachki@gmail.com) on 2017-01-06T16:59:11Z No. of bitstreams: 2 Tese - Walid Abdala Rfaei Jradi - 2016.pdf: 5339936 bytes, checksum: 0a0a6bdc4791ee31c229b5175ae3af03 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-01-09T09:29:25Z (GMT) No. of bitstreams: 2 Tese - Walid Abdala Rfaei Jradi - 2016.pdf: 5339936 bytes, checksum: 0a0a6bdc4791ee31c229b5175ae3af03 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-01-09T09:29:25Z (GMT). No. of bitstreams: 2 Tese - Walid Abdala Rfaei Jradi - 2016.pdf: 5339936 bytes, checksum: 0a0a6bdc4791ee31c229b5175ae3af03 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-11-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The present work studies and proposes GPU-based parallel algorithms and implementations for the problem of macroscopic assignment of urban traffic on large-scale networks, promoting an in-depth investigation on each sub-problem that must be efficiently solved during the traffic assignment process. Among the main contributions of this work, there are: 1) the first GPU-based algorithm for the enumeration of chordless cycles; 2) a new parallel GPU-based shortest path algorithm that takes advantage of some common properties of urban traffic networks; a refinement in the parallel reduction implementation proposed by one of the leaders in the GPU market, which resulted in a 2.8x speedup relative to its original version; and finally, 3) a parallel algorithm for the macroscopic traffic assignment problem, 39x faster than the equivalent sequential approach when applied to large scale networks. The main goal of this thesis is to contribute to the extension of the PET-Gyn software, proposing efficient GPU data structures and parallel algorithms for a faster resolution of two well known problems in the literature: The Traffic Assignment Problem (TAP) and the Enumeration of Chordless Cycles. When applied to difficult input sets, the performed experiments showed a clear advantage of the parallel algorithms over their sequential versions. / O presente trabalho estuda e propõe algoritmos e implementações paralelas baseadas em GPU para o problema de alocação macroscópica de tráfego urbano em redes de grande porte, promovendo uma investigação aprofundada de cada sub-problema que deve ser resolvido de forma eficiente durante o processo de atribuição de tráfego. Entre as principais contribuições deste trabalho, estão: 1) o primeiro algoritmo baseado em GPU para a enumeração de ciclos sem corda; 2) um novo algoritmo de caminho mínimo paralelo que tira vantagem de algumas propriedades comuns das redes de tráfego urbano; Um refinamento na implementação de redução paralela proposta por um dos líderes no mercado de GPU, o que resultou em uma aceleração de 2,8x em relação à sua versão original; 3) e, finalmente, um algoritmo paralelo para o problema de alocação macroscópica de tráfego, 39x mais rápido do que a abordagem equivalente sequencial quando aplicado a redes de larga escala. O objetivo principal desta tese é de contribuir para a expansão do software PET-Gyn, propondo estruturas de dados de GPU eficientes e algoritmos paralelos para uma resolução mais rápida de dois problemas bem conhecidos na literatura: O Problema de Alocação de Tráfego e a Enumeração de Ciclos sem Corda. Quando aplicados a conjuntos de entrada difíceis, os experimentos realizados mostraram uma clara vantagem dos algoritmos paralelos sobre suas versões sequenciais.
68

Assessment Of Scenarios For Sustainable Transportation At Metu Campus

Altintasi, Oruc 01 January 2013 (has links) (PDF)
Sustainable transportation aims encouragement of non-motorized (pedestrian and bicyclist) and shared-ride transportation modes instead of car-dependent travels. This is important for university campuses, as they have better chance to implement such policies in a rather controlled traffic network, and can set an example to other communities. Most of sustainable campus transportation programs boil down to reduction of car-based emission cost of campus mobility, which is always the first step in developing more sustainable transportation policies. Middle East Technical University (METU), Ankara has a large campus area and a population over 30,000 people. To develop sustainable campus transportation policies, it was important to quantify the current levels of mobility and vehicle emissions within the campus, which was the main motivation behind this study. This required determination of i) campus origin-destination matrix, ii) in-campus vehicle-km-travelled (vehicle-km), and iii) carbon emissions. Travel data obtained from different sources, including the gate entry with RFID systems enabled analysis of different user groups, such as academic and administrative personnel and students, separately. The traffic simulations were prepared in PTV VISUM, which provided both speed and vehicle-km values for road segments, and could represent multi-user group demand matrices in a single traffic assignment. Based on the base case mobility and emission values, more sustainable campus transportation policies were simulated in PTV VISUM, and assessed in terms of carbon emission impacts. Discouraging of private car usage by students seemed the first and simplest action.
69

Designing Urban Road Congestion Charging Systems : Models and Heuristic Solution Approaches

Ekström, Joakim January 2008 (has links)
The question of how to design a congestion pricing scheme is difficult to answer and involves a number of complex decisions. This thesis is devoted to the quantitative parts of designing a congestion pricing scheme with link tolls in an urban car traffic network. The problem involves finding the number of tolled links, the link toll locations and their corresponding toll level. The road users are modeled in a static framework, with elastic travel demand. Assuming the toll locations to be fixed, we recognize a level setting problem as to find toll levels which maximize the social surplus. A heuristic procedure based on sensitivity analysis is developed to solve this optimization problem. In the numerical examples the heuristic is shown to converge towards the optimum for cases when all links are tollable, and when only some links are tollable. We formulate a combined toll location and level setting problem as to find both toll locations and toll levels which maximize the net social surplus, which is the social surplus minus the cost of collecting the tolls. The collection cost is assumed to be given for each possible toll location, and to be independent of toll level and traffic flow. We develop a new heuristic method which is based on repeated solutions of an approximation to the combined toll location and level setting problem. Also, a known heuristic method for locating a fixed number of toll facilities is extended, to find the optimal number of facilities to locate. Both heuristics are evaluated on two small networks, where our approximation procedure shows the best results. Our approximation procedure is also employed on the Sioux Falls network. The result is compared with different judgmental closed cordon structures, and the solution suggested by our method clearly improves the net social surplus more than any of the judgmental cordons.
70

Designing Urban Road Congestion Charging Systems : Models and Heuristic Solution Approaches

Ekström, Joakim January 2008 (has links)
<p>The question of how to design a congestion pricing scheme is difficult to answer and involves a number of complex decisions. This thesis is devoted to the quantitative parts of designing a congestion pricing scheme with link tolls in an urban car traffic network. The problem involves finding the number of tolled links, the link toll locations and their corresponding toll level. The road users are modeled in a static framework, with elastic travel demand.</p><p>Assuming the toll locations to be fixed, we recognize a level setting problem as to find toll levels which maximize the social surplus. A heuristic procedure based on sensitivity analysis is developed to solve this optimization problem. In the numerical examples the heuristic is shown to converge towards the optimum for cases when all links are tollable, and when only some links are tollable.</p><p>We formulate a combined toll location and level setting problem as to find both toll locations and toll levels which maximize the net social surplus, which is the social surplus minus the cost of collecting the tolls. The collection cost is assumed to be given for each possible toll location, and to be independent of toll level and traffic flow. We develop a new heuristic method which is based on repeated solutions of an approximation to the combined toll location and level setting problem. Also, a known heuristic method for locating a fixed number of toll facilities is extended, to find the optimal number of facilities to locate. Both heuristics are evaluated on two small networks, where our approximation procedure shows the best results.</p><p>Our approximation procedure is also employed on the Sioux Falls network. The result is compared with different judgmental closed cordon structures, and the solution suggested by our method clearly improves the net social surplus more than any of the judgmental cordons.</p>

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