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1
Bekmann, Joachim Peter Computer Science & Engineering Faculty of Engineering UNSW. "Rapid development of problem-solvers with HeurEAKA! - a heuristic evolutionary algorithm and incremental knowledge acquisition approach." Awarded by:University of New South Wales. School of Computer Science and Engineering, 2006. http://handle.unsw.edu.au/1959.4/25748.
Testo completoAbstract (sommario):
A new approach for the development of problem-solvers for combinatorial problems is proposed in this thesis. The approach combines incremental knowledge acquisition and probabilistic search algorithms, such as evolutionary algorithms, to allow a human to rapidly develop problem-solvers in new domains in a framework called HeurEAKA. The approach addresses a known problem, that is, adapting evolutionary algorithms to the search domain by the introduction of domain knowledge. The development of specialised problem-solvers has historically been labour intensive. Implementing a problem-solver from scratch is very time consuming. Another approach is to adapt a general purpose search strategy to the problem domain. This is motivated by the observation that in order to scale an algorithm to solve complex problems, domain knowledge is needed. At present there is no systematic approach allowing one to efficiently engineer a specialpurpose search strategy for a given search problem. This means that, for example, adapting evolutionary algorithms (which are general purpose algorithms) is often very difficult and has lead some people to refer to their use as a ???black art???. In the HeurEAKA approach, domain knowledge is introduced by incrementally building a knowledge base that controls parts of the evolutionary algorithm. For example, the fitness function and the mutation operators in a genetic algorithm. An evolutionary search algorithm ismonitored by a human whomakes recommendations on search strategy based on individual solution candidates. It is assumed that the human has a reasonable intuition of the search problem. The human adds rules to a knowledge base describing how candidate solutions can be improved, or why they are desirable or undesirable in the search for a good solution. The incremental knowledge acquisition approach is inspired by the idea of (Nested) Ripple Down Rules. This approach sees a human provide exception rules to rules already existing in the knowledge base using concrete examples of inappropriate performance of the existing knowledge base. The Nested Ripple Down Rules (NRDR) approach allows humans to compose rules using concepts that are natural and intuitive to them. In HeurEAKA, NRDR are significantly adapted to form part of a probabilistic search algorithm. The probabilistic search algorithms used in the presented system are a genetic algorithm and a hierarchical bayesian optimization algorithm. The success of the HeurEAKA approach is demonstrated in experiments undertaken on industrially relevant domains. Problem-solvers were developed for detailed channel and switchbox routing in VLSI design and traffic light optimisation for urban road networks. The problem-solvers were developed in a short amount of time, in domains where a large amount of effort has gone into developing existing algorithms. Experiments show that chosen benchmark problems are solved as well or better than existing approaches. Particularly in the traffic light optimisation domain excellent results are achieved.
2
Agdeppa, Rhoda Padua. "Studies on Mathematical Models of Traffic Equilibria." 京都大学 (Kyoto University), 2009. http://hdl.handle.net/2433/123831.
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3
Yue, Yang, and 樂陽. "Spatial-temporal dependency of traffic flow and its implications for short-term traffic forecasting." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B35507366.
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4
Mason, Anthony David. "Mathematical models of road traffic, and related problems." Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624189.
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5
Sze, Nang-ngai, and 施能藝. "Quantitative analyses for the evaluation of traffic safety and operations." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39707398.
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6
Lierkamp, Darren. "Simulating the effects of following distance on a high-flow freeway." Full text available online (restricted access), 2003. http://images.lib.monash.edu.au/ts/theses/Lierkamp.pdf.
Testo completoAbstract (sommario):
"CP830 Research Project and Thesis 2". Includes bibliographical references (p. 80-93) Electronic reproduction.[S.l. :s.n.],2003.Electronic data.Mode of access: World Wide Web.System requirements: Adobe Acrobat reader software for PDF files.Access restricted to institutions with a subscription.
7
Yan, Li, and 顏理. "On the traffic flow control system." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39431174.
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8
Wong, Chun-kuen, and 黃春權. "Dynamic macroscopic modeling of highway traffic flows." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31243757.
Testo completo
9
張詠敏 and Wing-man Cheung. "Dynamic traffic assignment for congested highway network." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B42575886.
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10
Peng, Jixian, and 彭继娴. "Macroscopic characteristics of dense road networks." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/195994.
Testo completoAbstract (sommario):
In the continuum modeling of traffic networks, a macroscopic cost-flow function (MCF) and macroscopic fundamental diagram (MFD) can be used to represent the fundamental relationships between traffic quantities such as speed, flow, and density. The MCF governs the steady-state cost-flow relationship, whereas the MFD represents the instantaneous inter-relationship between speed, flow, and density of traffic streams. This thesis explores the influence of network topologies on the MCF and MFD.
The Hong Kong road system is divided into unit-sized road networks with various physical characteristics for which the network structure and signal timings are reserved. By universally scaling the origin-destination (OD) matrices of the morning peak, traffic conditions ranging from free-flow to congestion are created for microscopic simulation. From the simulation results, an MCF that relates the average journey time and the number of vehicles traveling through the network in one hour and an MFD that relates space to the mean speed and average density aggregated across 300s intervals are derived. The MCF and MFD are calibrated with mathematical models for each network.
The density of roads, junctions, and signal junctions all influence the value of the macroscopic parameters in the MCF and MFD, and predictive equations are constructed that relate the macroscopic parameters to the network topological characteristics. Based on the fitting performance of the mathematical models, recommendations are made for selecting MCF and MFD models for continuum modeling.<br>published_or_final_version<br>Civil Engineering<br>Master<br>Master of Philosophy
11
Wong, Chi-kwong, and 黃志光. "Lane-based optimization method for traffic signal design." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B31246096.
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12
Ho, Hung-wai, and 何鴻威. "A continuum modeling approach to traffic equilibrium problems." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B31938267.
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13
Lau, Chi-yung, and 劉智勇. "Numerical studies on a few cellular automation traffic models." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31227521.
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14
溫建勇 and Kin-yung Wan. "Biham-middleton-levine traffic model in different spatial dimensions." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1998. http://hub.hku.hk/bib/B3122183X.
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15
Nagarajan, Krishnamurthy. "New resource allocation strategies based on statistical network traffic models." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/33437.
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Ernst, Wolfgang F. "The economic rationale for stochastic urban transport models and travel behaviour : a mathematical programming approach to quantitative analysis with Perth data." UWA Business School, 2003. http://theses.library.uwa.edu.au/adt-WU2005.0004.
Testo completoAbstract (sommario):
[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.
17
Kim, Changkyun. "Development and evaluation of traffic prediction systems." Diss., This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06062008-164007/.
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Lee, Wingyee Emily Electrical Engineering & Telecommunications Faculty of Engineering UNSW. "Scheduling real-time traffic in wireless networks." Awarded by:University of New South Wales. Electrical Engineering & Telecommunications, 2007. http://handle.unsw.edu.au/1959.4/40737.
Testo completoAbstract (sommario):
This dissertation concerns the problem of scheduling real-time traffic in wireless TDMA channels. The most important characteristic of real-time traffic is that it has straight end-to-end delay constraint. We begin the investigation by studying a scheduling principle which naturally achieves the best delay performance in stationary channel conditions. Since the resulting scheduling algorithm maintains equal flow delays across the whole system, it is termed the equal-delay policy. There are a number of advantages associated with this scheduling method. First, it is very simple and practical to implement in real system. Secondly, it can be easily modelled mathematically and admits an analytical solution, which is very important for the construction of an admission control algorithm, we present a mathematical model describing the dynamics of the scheduling system, as well as devising a tractable analytical solution to the problem. A third advantage of the equal-delay policy is that it can be easily extended to support flows with multiple delay constraints. We propose a multiple-class scheduling scheme based on similar allocation concepts as the equal-delay technique. The extended scheme can similarly be mathematically modelled and analytically characterized. A natural objection to the above proposed techniques is that wireless transmission resources can be under-utilized, since the scheduling algorithm pays no attention to the changing individual channel conditions. The reduction in channel utilization can also adversely affect the delay performance, We explain this phenomenon and study the impacts for a variety of different channel characteristics, Specifically, we propose an alternative channel-aware scheduling policy, which aims to maximize channel utilization while keeping a minimum probability of delay violation, The proposed channel-aware policy achieves near-optimal delay performance. However, unlike in the equal-delay case, the channel-aware policy is not practical to implement in a real system. The complicated system dynamics associated with the channel-aware scheme also hamper the development of a mathematical model and analytical solution for admission control. On the other hand, we observe from simulation results that under most circumstances, the equal-delay scheme achieves close to the pertonnance obtained by the channel-aware technique, With the additional benefits of simplicity and admitting analytical analysis. the equal-delay policy appears to be a more practical and suitable choice for scheduling real-time traffic in wireless networks.
19
Sivanandan, R. "A linear programming approach for synthesizing origin-destination (O-D) trip tables from link traffic volumes." Diss., This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-07102007-142518/.
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Fung, Wen-chi Sylvia, and 馮韻芝. "Calibration and validation of transit network assignment models." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B34624211.
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21
Zhu, Jiasong, and 朱家松. "A self-learning short-term traffic forecasting system through dynamic hybrid approach." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39634516.
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22
Ye, Qing, and 叶青. "Short-term traffic speed forecasting based on data recorded at irregular intervals." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B47250732.
Testo completoAbstract (sommario):
Efficient and comprehensive forecasting of information is of great importance
to traffic management. Three types of forecasting methods based on irregularly
spaced data—for situations when traffic detectors cannot be installed to generate
regularly spaced data on all roads—are studied in this thesis, namely, the single
segment forecasting method, multi-segment forecasting method and model-based
forecasting method.
The proposed models were tested using Global Positioning System (GPS) data
from 400 Hong Kong taxis collected within a 2-kilometer section on Princess
Margaret Road and Hong Chong Road, approaching the Cross Harbour Tunnel.
The speed limit for the road is 70 km/h. It has flyovers and ramps, with a small
number of merges and diverges. There is no signalized intersection along this road
section. A total of 14 weeks of data were collected, in which the first 12 weeks of
data were used to calibrate the models and the last two weeks of data were used for
validation.
The single-segment forecasting method for irregularly spaced data uses a
neural network to aggregate the predicted speeds from the naive method, simple
exponential smoothing method and Holt’s method, with explicit consideration of
acceleration information. The proposed method shows a great improvement in
accuracy compared with using the individual forecasting method separately. The
acceleration information, which is viewed as an indicator of the phase-transition
effect, is considered to be the main contribution to the improvement.
The multi-segment forecasting method aggregates not only the information
from the current forecasting segment, but also from adjacent segments. It adopts the
same sub-methods as the single-segment forecasting method. The forecasting
results from adjacent segments help to describe the phase-transition effect, so that
the forecasting results from the multi-segment forecasting method are more
accurate than those that are obtained from the single segment forecasting method.
For one-second forecasting length, the correlation coefficient between the forecasts
from the multi-segment forecasting method and observations is 0.9435, which
implies a good consistency between the forecasts and observations.
While the first two methods are based on pure data fitting techniques, the third
method is based on traffic models and is called the model-based forecasting
method. Although the accuracy of the one-second forecasting length of the
model-based method lies between those of the single-segment and multi-segment
forecasting methods, its accuracy outperforms the other two for longer forecasting
steps, which offers a higher potential for practical applications.<br>published_or_final_version<br>Civil Engineering<br>Master<br>Master of Philosophy
23
Al-Malik, Mohammed Saleh. "An investigation and development of a combined traffic signal control-traffic assignment model." Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/21425.
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Sun, Wenjun, and 孫文君. "Front tracking algorithm for the Lighthill-Whitham-Richards model for a traffic network." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B40687624.
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Zhou, Ji Zhe. "Modeling and dynamic routing for traffic flow through multi-agent system." Thesis, University of Macau, 2018. http://umaclib3.umac.mo/record=b3950602.
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Zhou, Dingshan Sam. "An integrated traffic incident detection model /." Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p9992952.
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27
Lloyd, Evan Robert. "A model for the economic analysis of road projects in an urban network with interrelated incremental traffic assignment method." University of Western Australia. Economics Discipline Group, 2005. http://theses.library.uwa.edu.au/adt-WU2005.0083.
Testo completoAbstract (sommario):
[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
28
Chen, Wenqin, and 陳文欽. "An analytical shock-fitting approach to the solution of the Lighthill-Whitham-Richards traffic flow model." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B38724650.
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Wong, Chung-yin Philip, and 黃仲賢. "The development of pedestrian flow model." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B48194025.
Testo completoAbstract (sommario):
This dissertation reported on the findings of the characteristics of the pedestrian
flows in Chinese New Year Eve Fair in Hong Kong and, the recommendations to its
crowd control measures. Since most of the pedestrian flow models were developed
for general purposes under normal condition, special models developed specifically
for major events such as bazaars, fairs and festivals in Hong Kong were required to
understand their pedestrian flow patterns. In this dissertation, pedestrian flows in the
Fair were videotaped and data was extracted for calibrating several pedestrian flow
models. These included the conventional models developed by Greenshields,
Greenberg, Pipes-Munjal, Underwood, Drake, Wong et al. and four modifications of
these models for simulating isotropic and bi-directional pedestrian flow scenarios.
The free flow speed of the pedestrians in the Chinese New Year Eve Fair was found
to be around 0.69-0.84 m/s, slower than those identified in other researches. Besides,
the results of these models showed the relationships between walking speed, density
and flow of the pedestrians in the Fair. Also, the effects of bi-directional flow to
pedestrian flows were assessed and quantified. These findings obtained from models
were then used as a basis for formulating crowd control strategy of major events in
Hong Kong.<br>published_or_final_version<br>Transport Policy and Planning<br>Master<br>Master of Arts in Transport Policy and Planning
30
Xie, Siqi, and 谢思琪. "Observational studies of pedestrian flows." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B49617990.
Testo completoAbstract (sommario):
Walking is an environmentally friendly mode of transportation. A better understanding of pedestrian activities and effective planning of walking facilities are particularly important for densely populated Asian cities like Hong Kong. Empirical studies on pedestrian flows can be classified as controlled experiments and observational surveys. Controlled experiments are flexible and can be designed to fulfill the requirements of specific studies and eliminate influence from unrelated factors. Observational surveys provide data for pedestrian movements in different types of walking facilities. This thesis aims to develop a mathematical model for multidirectional pedestrian flows based on knowledge obtained from both a controlled experiment and observational surveys on three different walking facilities. Bayesian inference is adopted for model calibration, as it can combine the prior information from the controlled experiment and the observed data from the observational surveys.
The proposed model is based on Drake’s (1967) model of traffic flow. However, multidirectional pedestrian flows are much more complicated than the unidirectional and bidirectional flows. Therefore, instead of relating the speed of a pedestrian stream solely to pedestrian density, the flow ratio and intersecting angles between streams are introduced as factors that may influence stream speed. The proposed model takes the form of a set of structural equations rather than a single deterministic function.
By applying Bayesian inference, the proposed model is calibrated with the three sets of observed data respectively, based on the prior distribution specified by the controlled experiment results. Finally, pedestrian movements in three different walking facilities are analyzed based on the properties of the calibrated model.<br>published_or_final_version<br>Civil Engineering<br>Master<br>Master of Philosophy
31
Fox, Thomas Charles 1960. "Evaluation of change interval policies." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277160.
Testo completoAbstract (sommario):
An intensive examination was conducted to test the credibility of current traffic signal change interval policies founded on a kinematic equation developed nearly 30 years ago. The investigation involved the review of relevant literature as well as an extensive collection of data. The literature review and data analysis revealed that current change interval policies rely on the disproven assumption that traffic decelerates at a constant rate. The data analysis also demonstrated that traffic approach speed and deceleration distance affect the manner in which deceleration occurs. Based on the data analysis, an alternative treatment of the kinematic equation is proposed using surrogate deceleration rates. The surrogate rates offer a pragmatic set of input for the kinematic equation. Therefore, rather than yielding a change interval based on an inaccurate assumption, agencies can implement change intervals which are responsive to local traffic.
32
Kimathi, Mark E. M. [Verfasser], and Axel [Akademischer Betreuer] Klar. "Mathematical Models for 3-Phase Traffic Flow Theory / Mark E. M. Kimathi. Betreuer: Axel Klar." Kaiserslautern : Universitätsbibliothek Kaiserslautern, 2012. http://d-nb.info/1021039578/34.
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Roberts, Craig Arnold. "Modeling the relationships between microscopic and macroscopic travel activity on freeways : bridging the gap between current travel demand models and emerging mobile emission models." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/32873.
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34
Roy, Roger A. "An Application of Landscape Design to Student Academic Success." Fogler Library, University of Maine, 2006. http://www.library.umaine.edu/theses/pdf/RoyRA2006.pdf.
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35
Lam, Fung, and 林峰. "Internet inter-domain traffic engineering and optimizatioon." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31224581.
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Bhat, Sudarshana C. S. "Evaluation of Tidewater district's operations improvements program." Thesis, Virginia Tech, 1989. http://hdl.handle.net/10919/44108.
Testo completoAbstract (sommario):
The increasing congestion on the roads in the United States of America has become a topic
of much interest among the transportation planners. There is a limit to which there can be
building of new highways. Thus, the thrust for better utilization of the existing facilities is
gaining ground. This research project is aimed at a solution to problems of increasing travel
times due to congestion.
A case study of the toll road (Route 44) in the tidewater region of Virginia has been made as
an example of the common method of relieving congestion, ridesharing, which is being encouraged.
The failure of the proper maintenance of the HOV lanes on the Route 44 leading to
the subsequent rescinding of the same has been looked into. The use of DYNAMO programming
was made in order to simulate the conditions on the toll road and to get an idea of the
various alternatives which could be used to take care of the problem. On the basis of the
simulations carried out, and taking into account the views held by the commuters who did not
form a part of the ridesharing community, a method in which authorities could give an advantage
as far as travel time is concerned, has been proposed.<br>Master of Science
37
Brizendine, Laora Dauberman. "Low probability-high consequence considerations in a multiobjective approach to risk management." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-07112009-040353/.
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38
Fang, Yi. "An urban traffic network model using GIS technology." Virtual Press, 1992. http://liblink.bsu.edu/uhtbin/catkey/845978.
Testo completoAbstract (sommario):
This creative project was proposed to develop a GIS model for transportation planning purposes with the ARC/INFO software. The urban street network in the GIS model was based on urban arterial systems in the city of Muncie, Indiana. The model was also expected to demonstrate the applicability of GIS technology in transportation planning. Several transportation planning techniques were tested with the model which included road and traffic data inventory, optimum pathing, road capacity analysis, traffic shift study modeling, and graphic presentation. The case study was targeted on road capacity analysis of urban arterial network as well as study of alternative traffic route for the urban route of State Road 32 in Muncie. The project began with an discussion of GIS technology, GIS application in planning, and ARC/INFO software programs. Then an urban street information model was developed in form of digital network in the computer database which could perform the functions of data inventory, spatial traffic analysis, and mapping manipulation. Finally the case studies were performed to demonstrate the application of this GIS network model. The findings and analysis results generated by GIS operation were used to evaluate the traffic conditions as well as to determine the feasibility of alternative route for State Road tables, ARC/INFO macro programs, traffic maps, and print-out of analysis results.<br>Department of Urban Planning
39
Barnett, Joel Stephen. "On the Estimation of Volumes of Roadways: An Investigation of Stop-Controlled Minor Legs." PDXScholar, 2015. https://pdxscholar.library.pdx.edu/open_access_etds/2196.
Testo completoAbstract (sommario):
This effort seeks to answer the question; can a transferable model be developed from easily obtainable, publicly available land-use, census, roadway, and network data for the use in safety performance functions? 474 stop-controlled minor legs were used as the training data set using ordinary least squares regression. A best-fit model of maximum independent variables, n=12 was chosen using an exhaustive approach using Mallow's Cp to select the model with least bias in the predictors. The results of the analysis revealed that the combination of variables from Washington, Ohio, and North Carolina did not have a strong relationship. The best-fit model incorporated functional class information of the major-leg, minor leg functional class information, longitudinal markings, access to a parking lot, and population density of census tract. Validation of the model demonstrated an average 59 percent error between the model estimated and actual AADT values for validation data set (n=54). Furthermore, separate models for each state revealed a lack of uniformity in the dependent variables, and more variance description of the state specific AADT.
40
Powell, James Eckhardt. "Building a Multivariable Linear Regression Model of On-road Traffic for Creation of High Resolution Emission Inventories." PDXScholar, 2017. https://pdxscholar.library.pdx.edu/open_access_etds/3415.
Testo completoAbstract (sommario):
Emissions inventories are an important tool, often built by governments, and used to manage emissions. To build an inventory of urban CO2 emissions and other fossil fuel combustion products in the urban atmosphere, an inventory of on-road traffic is required. In particular, a high resolution inventory is necessary to capture the local characteristics of transport emissions. These emissions vary widely due to the local nature of the fleet, fuel, and roads.
Here we show a new model of ADT for the Portland, OR metropolitan region. The backbone is traffic counter recordings made by the Portland Bureau of Transportation at 7,767 sites over 21 years (1986-2006), augmented with PORTAL (The Portland Regional Transportation Archive Listing) freeway traffic count data. We constructed a regression model to fill in traffic network gaps using GIS data such as road class and population density. An EPA-supplied emissions factor was used to estimate transportation CO2 emissions, which is compared to several other estimates for the city's CO2 footprint.
41
Li, Lok-man Jennifer, and 李諾文. "Schedule delay of work trips in Hong Kong: anempirical analysis." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B40988041.
Testo completo
42
Hallmark, Shauna L. "Analysis and prediction of individual vehicle activity for microscopic traffic modeling." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/20736.
Testo completo
43
Hwang, Kuo-Ping. "Applying heuristic traffic assignment in natural disaster evacuation: a decision support system." Diss., Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/54455.
Testo completoAbstract (sommario):
The goal of this research is to develop a heuristic traffic assignment method to simulate the traffic flow of a transportation network at a real-time speed. The existing assignment methods are reviewed and a heuristic path-recording assignment method is proposed. Using the new heuristic assignment method, trips are loaded onto the network in a probabilistic approach for the first iteration; paths are recorded, and path impedance is computed as the basis for further assignment iteration. The real-time traffic assignment model developed with the new assignment method is called HEUPRAE. The difference in link traffic between this new assignment and Dial's multipath assignment ranges from 10 to 25 percent. Saving in computer time is about 55 percent. The proposed heuristic path-recording assignment is believed to be an efficient and reliable method.
Successful development of this heuristic assignment method helps solve those transportation problems which need assignment results at a real-time speed, and for which the assignment process lasts a couple of hours. Evacuation planning and operation are well suited to the application of this real-time heuristic assignment method.
Evacuation planning and operations are major activities in emergency management. Evacuation planning instructs people where to go, which route to take, and the time needed to accomplish an evacuation. Evacuation operations help the execution of an evacuation plan in response to the changing nature of a disaster.
The Integrated Evacuation Decision Support System (IEDSS) is a computer system which employs the evacuation planning model, MASSVAC2, and the evacuation operation model, HEUPRAE, to deal with evacuations. The IEDSS uses computer graphics to prepare input and interpret output. It helps a decision maker analyze the evacuation system, review evacuation plans, and issue an evacuation order at a proper time. Users of the IEDSS can work on evacuation problems in a friendly interactive visual environment.
The application of the IEDSS to the hurricane and flood problems for the city of Virginia Beach shows how IEDSS is practically implemented. It proves the usefulness of the IEDSS in coping with disasters.<br>Ph. D.
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Østerbø, Olav. "Mathematical modelling and analysis of communication networks: transient characteristics of traffic processes and models for end-to-end delay and delay-jitter." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Information Technology, Mathematics and Electrical Engineering, 2003. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-6.
Testo completoAbstract (sommario):
<p>The first part of the thesis (Part I) is devoted to find methods to describe transient behaviour of traffic processes, where the main emphasis is put on the description and analysis of excess periods and excess volumes of quite general stochastic processes. By assuming that traffic changes on different time scales, the transient characteristics such as excess periods could be important measures to describe periods of congestion on a communication link and moreover, the corresponding excess volume will represent lost information during such periods. Although the results obtained are of rather general nature, they provide some rather fundamental insight into transient characteristics of traffic processes. The distributions of the length of excess periods may then be expressed it terms of some excess probabilities that are related to the minimum of the process in the time interval considered. Similar relationsfor the excess volumes are harder to obtain and require the joint probability of the arrived volume and the minimum of the process in the same time interval.</p>
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Olstam, Johan. "A model for simulation and generation of surrounding vehicles in driving simulators." Licentiate thesis, Linköpings universitet, Institutionen för teknik och naturvetenskap, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-4672.
Testo completoAbstract (sommario):
Driving simulators are used to conduct experiments on for example driver behavior, road design, and vehicle characteristics. The results of the experiments often depend on the traffic conditions. One example is the evaluation of cellular phones and how they affect driving behavior. It is clear that the ability to use phones when driving depends on traffic intensity and composition, and that realistic experiments in driving simulators therefore has to include surrounding traffic. This thesis describes a model that generates and simulates surrounding vehicles for a driving simulator. The proposed model generates a traffic stream, corresponding to a given target flow and simulates realistic interactions between vehicles. The model is built on established techniques for time-driven microscopic simulation of traffic and uses an approach of only simulating the closest neighborhood of the driving simulator vehicle. In our model this closest neighborhood is divided into one inner region and two outer regions. Vehicles in the inner region are simulated according to advanced behavioral models while vehicles in the outer regions are updated according to a less time-consuming model. The presented work includes a new framework for generating and simulating vehicles within a moving area. It also includes the development of enhanced models for car-following and overtaking and a simple mesoscopic traffic model. The developed model has been integrated and tested within the VTI Driving simulator III. A driving simulator experiment has been performed in order to check if the participants observe the behavior of the simulated vehicles as realistic or not. The results were promising but they also indicated that enhancements could be made. The model has also been validated on the number of vehicles that catches up with the driving simulator vehicle and vice versa. The agreement is good for active and passive catch-ups on rural roads and for passive catch-ups on freeways, but less good for active catch-ups on freeways.
46
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.
Testo completoAbstract (sommario):
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.
47
Witosurapot, Suntorn, and wsuntorn@fivedots coe psu ac th. "Resolving competition for resources between multimedia and traditional Internet applications." Swinburne University of Technology, 2004. http://adt.lib.swin.edu.au./public/adt-VSWT20050309.123048.
Testo completoAbstract (sommario):
Although the Internet is the dominant broadband network, it still has a fundamental shortcoming in traffic management that does not properly support efficient use of resources together with differentiated quality of service for mixed traffic types. Even though a number of mechanisms have been proposed under key approaches of resource adaptation, resource reservation, and resource pricing, this problem remains unsolved to date because of its complexity and the way it relates to so many considerations of engineering and economics, and the diverse range of services desired by users. Hence it is considered difficult to devise a perfect mechanism that can universally solve this problem. In this respect, this dissertation contributes to insights into potential combinations and trade-offs of key approaches above in some efficient manner for managing traffic and scarce resources in the Internet. The first part of this work considers the combination of relaxed resource reservation and resource pricing schemes for handling the unfair bandwidth distribution problem in soft-bandwidth guarantee services of the Differentiated Services (DiffServ) Internet. We show that this unfairness problem can be handled using a network-user cooperative approach that addresses both individual user satisfaction and global optimization. We propose to add a mechanism based on price-based feedback signaling to DiffServ-capable routers providing Assured Forwarding (AF) Service so that they can offer per-flow signaling. This still allows them to work at an aggregate traffic level, hence the scalability feature of the DiffServ network can be retained. Our proposed mechanism allows the network to offer reliable service assurances via a distributed optimization algorithm, without introducing special protocols or requiring routers to have access of individual user requirements. Moreover, it can provide incentives for users to cooperate so that optimum performance can be accomplished. This approach has broad applicability and is relevant to all types of assured service classes. The second part of this work considers the combination of a specific resource pricing scheme based on a distributed optimization algorithm and multimedia adaptation schemes. Such a capability has not been available because most utility functions of multimedia applications do not meet the concavity constraints required by optimization algorithm. We proposed to overcome this limitation by redefining user utility functions into equivalent discrete forms and using combinatorial (discrete) optimization so that interfacing the resource-pricing scheme can be done in a normal way. However, to obtain feasible solutions in a scalable manner, an agent is included into the scheme for solving the combinatorial (discrete) optimization on behalf of a small group of users. In return, all users belonging to this group can benefit from social welfare maximization of their utilities over a network resource constraint. The last part of this work considers the combination of relaxed resource reservation and resource pricing schemes to enable a proper charging scheme for adaptive applications in the DiffServ Internet. We provide an optimization formulation of the problems of revenue and social welfare maximization, applied at a service provider (SP) who gives access to the DiffServ Internet. In this scheme, resources are provisioned per QoS-oriented class in a long time scale (service level agreement (SLA) duration), then priced based on user demand in the short time scale. We also show that the proposed charging scheme can provide feedback and incentives for users to use the network resource optimally via the standard packet marking, hence eliminating the need for specific pricing protocol. All of the proposals in this work can be used together, solving these key problems as a coordinated whole, and all use readily available network mechanisms.
48
Shell, Michael David. "Cascaded All-Optical Shared-Memory Architecture Packet Switches Using Channel Grouping Under Bursty Traffic." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4892.
Testo completoAbstract (sommario):
This work develops an exact logical operation model to predict the performance of the all-optical shared-memory architecture (OSMA) class of packet switches and provides a means to obtain a reasonable approximation of OSMA switch performance within certain types of networks, including the Banyan family.
All-optical packet switches have the potential to far exceed the bandwidth capability of their current electronic counterparts. However, all-optical switching technology is currently not mature. Consequently, all-optical switch fabrics and buffers are more constrained in size and can cost several orders of magnitude more than those of electronic switches. The use of shared-memory buffers and/or links with multiple parallel channels (channel grouping) have been suggested as ways to maximize switch performance with buffers of limited size. However, analysis of shared-memory switches is far more difficult than for other commonly used buffering strategies. Obtaining packet loss performance by simulation is often not a viable alternative to modeling if low loss rates or large networks are encountered. Published models of electronic shared-memory packet switches (ESMP) have primarily involved approximate models to allow analysis of switches with a large number of ports and/or buffer cells. Because most ESMP models become inaccurate for small switches, and OSMA switches, unlike ESMP switches, do not buffer packets unless contention occurs, existing ESMP models cannot be applied to OSMA switches. Previous models of OSMA switches were confined to isolated (non-networked), symmetric OSMA switches using channel grouping under random traffic. This work is far more general in that it also encompasses OSMA switches that (1) are subjected to bursty traffic and/or with input links that have arbitrary occupancy probability distributions, (2) are interconnected to form a network and (3) are asymmetric.
49
Yao, Yufeng. "Topics in Fractional Airlines." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14563.
Testo completoAbstract (sommario):
Fractional aircraft ownership programs offer companies and individuals all the benefits of owning private jet, such as safety, consistency, and guaranteed availability, at a fraction of the cost of owning an aircraft. In the fractional ownership model, the partial owners of an aircraft are entitled to certain number of hours per year, and the management company is responsible for all the operational considerations and making sure an aircraft is available to the owners at the requested time and location.
This thesis research proposes advance optimization techniques to help the management company to optimally operate its available resources and provides tools for strategic decision making. The contributions of this thesis are:
(i) The development of optimization methodologies to assign and schedule aircraft and crews so that all flight requests are covered at the lowest possible cost. First, a simple model is developed to solve the crew pairing and aircraft routing problem with column generation assuming that a crew stays with one specific aircraft during its duty period. Secondly, this assumption is partially relaxed to improve resource utilization by revising the simple model to allow a crew to use another aircraft when its original aircraft goes under long maintenance. Thirdly, a new comprehensive model utilizing Benders decomposition technique and a fleet-station time line is proposed to completely relax the assumption that crew stays with one specific aircraft. It combines the fleet assignment, aircraft routing, and crew pairing problems. In the proposed methodologies, real world details are taken into consideration, such as crew transportation and overtime costs, scheduled and unscheduled maintenance effects, crew rules, and the presence of non-crew-compatible fleets. Scheduling with time windows is also discussed.
(ii) The analysis of operational strategies to provide decision making support. Scenario analyses are performed to provide insights on improving business profitability and aircraft availability, such as impact of aircraft maintenance, crew swapping, effect of increasing demand by Jet-card and geographical business expansion, size of company owned aircraft, and strategies to deal with the stochastic feature of unscheduled maintenance and demand.
50
Zambrano, Martínez Jorge Luis. "Efficient Traffic Management in Urban Environments." Doctoral thesis, Universitat Politècnica de València, 2019. http://hdl.handle.net/10251/129865.
Testo completoAbstract (sommario):
[ES] En la actualidad, uno de los principales desafíos a los que se enfrentan las grandes áreas metropolitanas es la congestión provocada por el tráfico, la cual se ha convertido en un problema importante al que se enfrentan las autoridades de cada ciudad. Para abordar este problema es necesario implementar una solución eficiente para controlar el tráfico que genere beneficios para los ciudadanos, como reducir los tiempos de viaje de los vehículos y, en consecuencia, el consumo de combustible, el ruido, y la contaminación ambiental. De hecho, al analizar adecuadamente la demanda de tráfico, es posible predecir las condiciones futuras del tráfico, y utilizar esa información para la optimización de las rutas tomadas por los vehículos. Este enfoque puede ser especialmente efectivo si se aplica en el contexto de los vehículos autónomos, que tienen un comportamiento más predecible, lo cual permite a los administradores de la ciudad mitigar los efectos de la congestión, como es la contaminación, al mejorar el flujo de tráfico de manera totalmente centralizada.
La validación de este enfoque generalmente requiere el uso de simulaciones que deberían ser lo más realistas posible. Sin embargo, lograr altos grados de realismo puede ser complejo cuando los patrones de tráfico reales, definidos a través de una matriz de Origen/Destino (O-D) para los vehículos en una ciudad, son desconocidos, como ocurre la mayoría de las veces. Por lo tanto, la primera contribución de esta tesis es desarrollar una heurística iterativa para mejorar el modelado de la congestión de tráfico; a partir de las mediciones de bucle de inducción reales hechas por el Ayuntamiento de Valencia (España), pudimos generar una matriz O-D para la simulación de tráfico que se asemeja a la distribución de tráfico real.
Si fuera posible caracterizar el estado del tráfico prediciendo las condiciones futuras del tráfico para optimizar la ruta de los vehículos automatizados, y si se pudieran tomar estas medidas para mitigar de manera preventiva los efectos de la congestión con sus problemas relacionados, se podría mejorar el flujo de tráfico en general. Por lo tanto, la segunda contribución de esta tesis es desarrollar una Ecuación de Predicción de Tráfico para caracterizar el comportamiento en las diferentes calles de la ciudad en términos de tiempo de viaje con respecto al volumen de tráfico, y aplicar una regresión logística a esos datos para predecir las condiciones futuras del tráfico.
La tercera y última contribución de esta tesis apunta directamente al nuevo paradigma de gestión de tráfico previsto, tratándose de un servidor de rutas capaz de manejar todo el tráfico en una ciudad, y equilibrar los flujos de tráfico teniendo en cuenta las condiciones de congestión del tráfico presentes y futuras. Por lo tanto, realizamos un estudio de simulación con datos reales de congestión de tráfico en la ciudad de Valencia (España), para demostrar cómo se puede mejorar el flujo de tráfico en un día típico mediante la solución propuesta. Los resultados experimentales muestran que nuestra solución, combinada con una actualización frecuente de las condiciones del tráfico en el servidor de rutas, es capaz de lograr mejoras sustanciales en términos de velocidad promedio y tiempo de trayecto, ambos indicadores de un menor grado de congestión y de una mejor fluidez del tráfico.<br>[CA] En l'actualitat, un dels principals desafiaments als quals s'enfronten les grans àrees metropolitanes és la congestió provocada pel trànsit, que s'ha convertit en un problema important al qual s'enfronten les autoritats de cada ciutat. Per a abordar aquest problema és necessari implementar una solució eficient per a controlar el trànsit que genere beneficis per als ciutadans, com reduir els temps de viatge dels vehicles i, en conseqüència, el consum de combustible, el soroll, i la contaminació ambiental. De fet, en analitzar adequadament la demanda de trànsit, és possible predir les condicions futures del trànsit, i utilitzar aqueixa informació per a l'optimització de les rutes preses pels vehicles. Aquest enfocament pot ser especialment efectiu si s'aplica en el context dels vehicles autònoms, que tenen un comportament més predictible, i això permet als administradors de la ciutat mitigar els efectes de la congestió, com és la contaminació, en millorar el flux de trànsit de manera totalment centralitzada.
La validació d'aquest enfocament generalment requereix l'ús de simulacions que haurien de ser el més realistes possible. No obstant això, aconseguir alts graus de realisme pot ser complex quan els patrons de trànsit reals, definits a través d'una matriu d'Origen/Destinació (O-D) per als vehicles en una ciutat, són desconeguts, com ocorre la majoria de les vegades. Per tant, la primera contribució d'aquesta tesi és desenvolupar una heurística iterativa per a millorar el modelatge de la congestió de trànsit; a partir dels mesuraments de bucle d'inducció reals fetes per l'Ajuntament de València (Espanya), vam poder generar una matriu O-D per a la simulació de trànsit que s'assembla a la distribució de trànsit real.
Si fóra possible caracteritzar l'estat del trànsit predient les condicions futures del trànsit per a optimitzar la ruta dels vehicles automatitzats, i si es pogueren prendre aquestes mesures per a mitigar de manera preventiva els efectes de la congestió amb els seus problemes relacionats, es podria millorar el flux de trànsit en general. Per tant, la segona contribució d'aquesta tesi és desenvolupar una Equació de Predicció de Trànsit per a caracteritzar el comportament en els diferents carrers de la ciutat en termes de temps de viatge respecte al volum de trànsit, i aplicar una regressió logística a aqueixes dades per a predir les condicions futures del trànsit.
La tercera i última contribució d'aquesta tesi apunta directament al nou paradigma de gestió de trànsit previst. Es tracta d'un servidor de rutes capaç de manejar tot el trànsit en una ciutat, i equilibrar els fluxos de trànsit tenint en compte les condicions de congestió del trànsit presents i futures. Per tant, realitzem un estudi de simulació amb dades reals de congestió de trànsit a la ciutat de València (Espanya), per a demostrar com es pot millorar el flux de trànsit en un dia típic mitjançant la solució proposada. Els resultats experimentals mostren que la nostra solució, combinada amb una actualització freqüent de les condicions del trànsit en el servidor de rutes, és capaç d'aconseguir millores substancials en termes de velocitat faig una mitjana i de temps de trajecte, tots dos indicadors d'un grau menor de congestió i d'una fluïdesa millor del trànsit.<br>[EN] Currently, one of the main challenges that large metropolitan areas have to face is traffic congestion, which has become an important problem faced by city authorities. To address this problem, it becomes necessary to implement an efficient solution to control traffic that generates benefits for citizens, such as reducing vehicle journey times and, consequently, use of fuel, noise and environmental pollution. In fact, by properly analyzing traffic demand, it becomes possible to predict future traffic conditions, and to use that information for the optimization of the routes taken by vehicles. Such an approach becomes especially effective if applied in the context of autonomous vehicles, which have a more predictable behavior, thus enabling city management entities to mitigate the effects of traffic congestion and pollution by improving the traffic flow in a city in a fully centralized manner.
Validating this approach typically requires the use of simulations, which should be as realistic as possible. However, achieving high degrees of realism can be complex when the actual traffic patterns, defined through an Origin/Destination (O-D) matrix for the vehicles in a city, are unknown, as occurs most of the times. Thus, the first contribution of this thesis is to develop an iterative heuristic for improving traffic congestion modeling; starting from real induction loop measurements made available by the City Hall of Valencia, Spain, we were able to generate an O-D matrix for traffic simulation that resembles the real traffic distribution.
If it were possible to characterize the state of traffic by predicting future traffic conditions for optimizing the route of automated vehicles, and if these measures could be taken to preventively mitigate the effects of congestion with its related problems, the overall traffic flow could be improved. Thereby, the second contribution of this thesis was to develop a Traffic Prediction Equation to characterize the different streets of a city in terms of travel time with respect to the vehicle load, and applying logistic regression to those data to predict future traffic conditions.
The third and last contribution of this thesis towards our envisioned traffic management paradigm was a route server capable of handling all the traffic in a city, and balancing traffic flows by accounting for present and future traffic congestion conditions. Thus, we perform a simulation study using real data of traffic congestion in the city of Valencia, Spain, to demonstrate how the traffic flow in a typical day can be improved using our proposed solution. Experimental results show that our proposed solution, combined with frequent updating of traffic conditions on the route server, is able to achieve substantial improvements in terms of average travel speeds and travel times, both indicators of lower degrees of congestion and improved traffic fluidity.<br>Finally, I want to thank the Ecuatorian Republic through the "Secretaría de Educación Superior, Ciencia, Tecnología e Innovación" (SENESCYT), for granting me the scholarship to finance my studies.<br>Zambrano Martínez, JL. (2019). Efficient Traffic Management in Urban Environments [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/129865<br>TESIS