8 research outputs found

    Validação de dois cenários para avaliar o comportamento de peões em ambiente virtual

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    Dois cenários virtuais foram modelados, com base em duas passagens para peões reais. Foi efetuada a validação destes cenários, comparando valores de tempo até à colisão (TTC) obtidos em experiências virtuais realizadas por 10 participantes, com valores do TTC adquiridos através de gravações vídeo in situ. Verificou-se consistência nas respostas dos participantes em ambos os cenários, assim como semelhança dos valores médios do TTC adquiridos na experiência e em captações de vídeo. Conclui-se que a modelação dos cenários foi bem realizada, o que viabiliza a sua utilização para estudos de comportamento de peões.Este trabalho enquadra-se nas atividades do projeto de investigação AnPeB – Análise do comportamento de peões com base em ambientes simulados e sua incorporação na modelação de risco (PTDC/ECM-TRA/3568/2014), foi financiado no âmbito do projeto Promover a Produção Científica e Desenvolvimento Tecnológico e a Constituição de Redes Temáticas (3599-PPCDT) e comparticipado pelo Fundo Comunitário Europeu FEDER e da bolsa de doutoramento SFRH/BD/131638/2017, financiada pela Fundação para a Ciência e a Tecnologia

    Optimization Model of Transit Signal Priority Control for Intersection and Downstream Bus Stop

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    Transit signal priority has a positive effect on improving traffic condition and level of transit service in the urban area. In this paper, a passenger-based transit signal priority (TSP) optimization model is formulated to optimize intersection signal phasing based on minimizing accessibility-based passenger delay at the intersection and increased waiting-delay at the downstream bus stop simultaneously. Genetic Algorithm is utilized to calculate passenger-based optimization model that is calibrated by evening rush hour actual traffic data (17:30–18:30, October 13th–October 15th, 2015) along Shuiximen Boulevard in Nanjing, China. The performance of the proposed optimization model in decreasing delay and improving system reliability is simulated and evaluated by VISSIM-based simulation platform, and the results illustrate that the proposed optimization model presents promising outcomes in decreasing accessibility-based passenger delay at intersection (average reduction of 12%) and passenger waiting-delay at downstream bus service stop (average reduction of 18%) compared with traditional vehicle-based TSP optimization method in rush hour

    Overtaking Safety Evaluation and Setting of Auxiliary Lane on Two-Lane Highway in China

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    Overtaking experiments on four two-lane highways were conducted. The data of overtaking conflict time (the time difference between the time of driving back to the original lane and the time of meeting with the first opposing vehicle) and experimental drivers’ risk feeling were observed. Membership was adopted to denote the experimental drivers’ risk feelings which also denote the severity of traffic conflict. Membership ranges from 0 to 1 and corresponding risk becomes higher; that is, traffic conflict becomes more serious. According to the observed relationship between overtaking conflict time, and drivers’ risk feeling membership, Cauchy distribution function was adopted as membership function. The thresholds of the severity of traffic conflict were determined through Delphi method. The relationship model among traffic volume, overtaking conflict time and design speed was established according to experimental data. Then the idea of setting auxiliary lane on two-lane highway in China was presented. And the traffic volume values that need setting auxiliary lane corresponding to different design speed and traffic conflict degree were given according to the established model. It is expected to improve the traffic safety level of two-lane highway in China through setting auxiliary lane

    Critical Scenario Identification for Testing of Autonomous Driving Systems

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    Background: Autonomous systems have received considerable attention from academia and are adopted by various industrial domains, such as automotive, avionics, etc. As many of them are considered safety-critical, testing is indispensable to verify their reliability and safety. However, there is no common standard for testing autonomous systems efficiently and effectively. Thus new approaches for testing such systems must be developed.Aim: The objective of this thesis is two-fold. First, we want to present an overview of software testing of autonomous systems, i.e., relevant concepts, challenges, and techniques available in academic research and industry practice. Second, we aim to establish a new approach for testing autonomous driving systems and demonstrate its effectiveness by using real autonomous driving systems from industry.Research Methodology: We conducted the research in three steps using the design science paradigm. First, we explored the existing literature and industry practices to understand the state of the art for testing of autonomous systems. Second, we focused on a particular sub-domain - autonomous driving - and proposed a systematic approach for critical test scenario identification. Lastly, we validated our approach and employed it for testing real autonomous driving systems by collaborating with Volvo Cars.Results: We present the results as four papers in this thesis. First, we conceptualized a definition of autonomous systems and classified challenges and approaches, techniques, and practices for testing autonomous systems in general. Second, we designed a systematic approach for critical test scenario identification. We employed the approach for testing two real autonomous driving systems from the industry and have effectively identified critical test scenarios. Lastly, we established a model for predicting the distribution of vehicle-pedestrian interactions for realistic test scenario generation for autonomous driving systems. Conclusion: Critical scenario identification is a favorable approach to generate test scenarios and facilitate the testing of autonomous driving systems in an efficient way. Future improvement of the approach includes (1) evaluating the effectiveness of the generated critical scenarios for testing; (2) extending the sub-components in this approach; (3) combining different testing approaches, and (4) exploring the application of the approach to test different autonomous systems

    Constructing pedestrian-centric street mobility: Observation and simulation for design

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    There are three principal components to the research presented in this thesis: a video-observation study of pedestrian behaviours and interactions with traffic, leading to the development of an agent-based digital simulation, and demonstrating the potential of this simulation for designing pedestrian-centric interventions in the streetscape. The long-term objective is to devise streetscapes that responsively adapt to the needs of pedestrians. Since the advent of car culture in the late 1930s, the approaches to street design have prioritised efficient motorised traffic flow, restricting walking and neglecting the pedestrian point of view. In recent years, however, a growing interest in making urban spaces more pedestrian-friendly has emerged, popularising concepts such as walkability, shared space, and traffic calming. These approaches aim to promote active travel and reduce car dependency in order to mitigate congestion, pollution, accidents and other harms. Urban studies have concentrated primarily on pedestrian-only zones and utilised spatial features as a way to reach pedestrian-friendly streets. Meanwhile, transport studies have tended to approach the street from a throughput and vehicle-oriented stance. Despite these endeavours, pedestrian-oriented approaches appear to lack systematic consideration of pedestrian behaviours as they interact with motor vehicles and street infrastructure. My PhD research differs from prior studies by focusing on these behaviours and interactions to support a pedestrian-oriented street mobility system. The current design of streets communicates to pedestrians via its structures and signs, such as barriers, crossings, and lights, while its capacity to respond and adapt is minimal. In contrast, this thesis argues that, since the street environment is inherently dynamic, we should analyse its dynamics and design the street to be responsive. Through responsiveness, my aim is to increase the convenience of pedestrian movement whilst creating a safe experience. This PhD asks the question 'how to design a pedestrian-centric street system that dynamically manages street mobility?'. The research takes a practice-based and reflective approach, designing agent-based simulations based on a qualitative observational study. Designing a simulation accomplishes two things: 1) it creates a space for implementing and evaluating possible design interventions, and 2) it prompts new insights into the behavioural processes of pedestrians. My research has followed an iterative cycle in line with second-order cybernetics: in two feedback loops, the first study informed the second study while the second informed the first. The video observation of street behaviours particularly explored pedestrian decision and interaction processes, identifying pedestrians’ own observational strategies and their varying levels of risk-taking. These aspects are reflected in the simulation. The first chapter introduces the pedestrian issues on the street and sets out the key concepts in pedestrian-centric street design. The second chapter examines the literature and existing practice that addresses pedestrian and vehicle interactions on the street. Chapter three sets out the theoretical framework and the following chapter describes the methodology. The three subsequent chapters present the following studies: (1) understanding the context by conducting qualitative video observation in a real street environment to observe and document the relations between streets, pedestrians and vehicles; (2) creating an artificial pedestrian society for simulation purposes, using agent-based modelling, both to refine the understanding developed through video analysis and to create a platform for experimentation; (3) design and implementation of prototype responsive interventions within the simulation, focusing on localised changes in the environment to empower pedestrians. The last chapter reflects on these projects by discussing the research contributions in terms of methods, techniques, and practices. The methodological innovation includes combining qualitative and computational tools as well as the use of simulation and video analysis in an iterative and reflexive cycle. Theoretical contributions include evaluating streets through pedestrian dynamics, creating a taxonomy of existing pedestrian interventions according to their spatial and temporal impacts, and rethinking the street as a responsive environment. The practical component advances the technical state of the art by expanding the capabilities of pedestrian agents when negotiating with vehicles and making crossing decisions and demonstrates the potential for designing novel interventions in the streetscape, including those that respond to pedestrian behaviour. The last chapter, also, emphasises the role of reflective design practice and the place of simulation within it

    Assessing the Active Transportation Potential of Neighbourhood Models Using GIS

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    This study sought to determine how five neighbourhood models (the Grid, Loop and Cul-de-Sac, Fused Grid, New Urbanist and Greenway) compare in terms of the characteristics known to affect active transportation rates, and which model is most likely to be able to facilitate active transportation as a result. In order to do so, model principles and design characteristics of case study neighbourhoods were described and used to create a range of design specifications for each model. These specifications were then used to develop a GIS-based representation of an example neighbourhood for each model, which included the transportation network, parcels of different land use types and densities, homes and destinations. GIS, statistical and graph-based techniques were then used to comprehensively assess and compare the models in terms of their potential to facilitate walking and biking through the built environment correlates identified in through a literature review. The models were ranked on each variable, and then an overall comparison was made on the basis diversity (land use mix), density and design - the three dimensions identified by Cervero and Kockelman (1997) as being the key ways through which the built environment can contribute to creating walkable (and potentially bikeable) neighbourhoods. Additional measures related to trip characteristics and issues of importance to developers (such as buildable area) were also included. The results illustrate how each model’s unique approach to facilitating walking and/or biking is reflected in the built environment characteristics assessed. While a model that was strong in one category was often weaker in another (a finding which echoes that of Filion and Hammond, 2003), the three alternative models (Fused Grid, New Urbanist and Greenway) consistently fared better than the more traditional Grid and Loop and Cul-de-Sac designs, with the New Urbanist scoring the highest on the overall evaluation of walkability and bikeability and the Greenway the best on network design for cyclists. In addition to these findings, the study also provided an opportunity to explore several challenges related to model assessment, such as issues arising from frame choice, off-set networks, and the use of roads as proxies for active transportation networks

    Untersuchungen zu Verhaltensanpassungen von zu Fuß Gehenden bei der Interaktion mit hochautomatisierten Pkw

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    Bereits heute wird die Interaktion zwischen hochautomatisierten Pkw und zu Fuß Gehenden erforscht, um zukünftig einen sicheren und effizienten Straßenverkehrsfluss zu gewährleisten. Die hohe Automatisierung der dynamischen Fahrzeugführungsaufgabe bedingt nicht nur die Ergänzung, sondern den zeitweisen vollständigen Ersatz des Menschen als fahrende Person, weshalb die Mensch-Maschine-Schnittstelle (MMS) für die Interaktion zwischen hochautomatisierten Pkw und zu Fuß gehenden Personen an Bedeutung gewinnt. Diese technologisch induzierte Veränderung kann die Ursache für Verhaltensanpassungen von zu Fuß Gehenden im Straßenverkehr sein. Eine Forschungslücke besteht darin, die Verhaltensanpassungen von zu Fuß Gehenden zu untersuchen. Dementsprechend ist das Ziel dieser Arbeit, Verhaltensanpassungen zu Fuß Gehender bei der Interaktion mit hochautomatisierten Pkw unter dem Aspekt steigender Erfahrung des Menschen bei der Interaktion sowie der Automationstransparenz, als Variable der Gestaltung der MMS von hochautomatisierten Pkw, zu untersuchen. Zur Erfüllung dieser Zielstellung wurden zwei empirische Untersuchungen als explorative Interviewstudie mit 36 Teilnehmenden und als quasi-experimentelle Studie mit Messwiederholungen durchgeführt. Auf einem abgesperrten Testgelände interagierten 37 Versuchspersonen an drei aufeinanderfolgenden Versuchstagen mit einem hochautomatisierten Pkw als Realfahrzeug mit Wizard-of-Oz Konzept. Neben der interaktionsbezogenen Variablen der Bereitschaft zur Querung wurden das Vertrauen in und das mentale Modell bezüglich hochautomatisierter Pkw erhoben. Die Ergebnisse der Interviewstudie zeigen, dass Erfahrung eine zentrale Einflussgröße einer Verhaltensanpassung von zu Fuß Gehenden bei der Interaktion mit hochautomatisierten Pkw ist. Außerdem deckt sich das mentale Modell der interviewten Personen nicht mit dem konzeptuellen Modell eines hochautomatisierten Pkw. Aus den explorativen Erkenntnissen der Interviewstudie wurden Hypothesen abgeleitet, die in dem kontrollierten Feldtest geprüft wurden. Die Ergebnisse dieser zweiten empirischen Untersuchung zeigen, dass in Abhängigkeit der Fahrstrategie des Pkw und der Automationstransparenz die Bereitschaft zur Querung von zu Fuß Gehenden mit zunehmender Erfahrung bei der Interaktion mit hochautomatisierten Pkw zunimmt. Des Weiteren nimmt das Vertrauen von zu Fuß Gehenden in hochautomatisierte Pkw mit zunehmender Interaktionserfahrung zu. Demgegenüber entwickelt sich das mentale Modell der Versuchspersonen von einem hochautomatisierten Pkw nicht innerhalb der drei Versuchstage. Die Ausprägung des mentalen Modells bezüglich hochautomatisierter Pkw ist jedoch von der erlebten Automationstransparenz abhängig. Für die Erforschung der Interaktion zwischen zu Fuß Gehenden und hochautomatisierten Pkw bietet diese Arbeit einen Mehrwert, weil bislang experimentelle Untersuchungen zu Verhaltensanpassungen von zu Fuß Gehenden in realitätsnahen Untersuchungsumgebungen fehlen. Aus der Arbeit leitet sich die praktische Implikation ab, dass hochautomatisierte Pkw mit einer hohen Automationstransparenz gestaltet werden sollten, wenn sie mit zu Fuß Gehenden im Straßenverkehr interagieren
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