THE USE OF THREE-DIMENSIONAL VISUALIZATION TOOLS TO DETECT DEFICIENCIES IN GEOMETRIC ROADWAY DESIGNS

The use of three-dimensional (3D) visualization technologies in the field oftransportation sciences has contributed not only to the assessment of the impact of aroad project on its surroundings but also to the development and study of elementsof the geometric design itself. The present study aimed to assess the effectiveness ofthe use of 3D visualization tools in the detection of poor compatibility between thehorizontal and vertical alignments of a road project. The assessment was performedby conducting tests with groups of participants who were students from a civilengineering course with no experience in the development of geometric roadwaydesigns. These participants each assessed two road stretches: one stretch withunflawed coordination between the vertical and horizontal alignments of the roadand another stretch in which this coordination had been intentionally distorted. Itwas used an application software for roadway geometric designs that allowed the creation of a video of the trajectory of the targeted road. Subsequently, theparticipants answered a questionnaire that aided the interpretation of the resultsregarding the design deficiencies in road layouts perceived from the 3Dvisualization of the roadways

USO DE SIMULADORES DE DIREÇÃO APLICADO AO PROJETO DE SEGURANÇA VIÁRIA

O presente documento apresenta e discute tecnologias de visualização por meio de simuladores de direção e sua aplicação na engenharia de transportes, no que tange o projeto rodoviário e seu auxílio na melhoria da segurança das rodovias. O artigo foi elaborada com vistas a contribuir para o desenvolvimento e modernização tecnológica de parte dos estudos desenvolvidos no Brasil, relacionados com a segurança em rodovias, que se apresentam desatualizados em quase 15 anos em relação ao estado-da-arte desta linha de pesquisa em países pioneiros, como é o caso dos EUA, França, Itália, Alemanha. Esta desatualização culmina por contribuir para um cenário nacional trágico, onde, nos últimos dois anos, morreram 42.844 pessoas decorrentes de acidentes em trânsito – número que colocou as rodovias brasileiras entre as mais perigosas do mundo e o Brasil como 5º país entre os recordistas em mortes no trânsito. Apresenta inicialmente uma descrição técnica e as potencialidades e limitações dos simuladores de direção na condução de experimentos que apresentam realismo natural, com a vantagem do controle das diversas variáveis do estudo, sem risco aos usuários. Adicionalmente, descreve os principais tipos de simuladores de  direção existentes no mercado, com a caracterização dos três níveis de sofisticação – simuladores de nível básico, nível intermediário e alta fidelidade.

Comparação de GPS L1 com transdutores de deslocamentos e acelerômetros em aplicações de monitoramento de pontes.

The Department of Transportation of São Carlos Engineering School, Brazil, has been researching about deflections monitoring of large structures, mainly bridges, with Global Positioning System (GPS), since year 2000. This work had technical support from researches of the Timber Wood Laboratory of Sao Carlos Engineering School and researches of the Department of Geodesy and Geomatics Engineering from the University of New Brunswick, Canada. The experiments had the objective to compare the measurements of two geotechnical conventional instruments, displacement transducer and accelerometer, with L1 GPS receiver measurements. The evaluation with the displacement transducer was performed at a cable stayed timber bridge, measuring the amplitude and frequency of its dynamic displacements induced by the stepping of pedestrians. The comparison with the accelerometer consisted in applying a periodic vertical movement by means of an electro-mechanical device. GPS results were obtained by Phase Residual Method (PRM). As this method is not based on coordinate determination, it is very useful for measuring short-lived oscillations at millimeter level. The PRM is not susceptible to multipath-induced position errors (which can be up to several centimeters) and there are minimal satellite visibility constraints. By analyzing results with the different techniques, repeated tests results were obtained which indicate the precision and accuracy of GPS.O Departamento de Transportes da Escola de Engenharia de São Carlos, Brasil, tem desenvolvido pesquisas sobre monitoramento das deflexões de grandes estruturas, principalmente pontes, com o Sistema de Posicionamento Global (GPS), desde o ano de 2000. Este trabalho teve a colaboração de pesquisadores do Departamento de Madeiras da Escola de Engenharia de São Carlos e pesquisadores do Department of Geodesy and Geomatics Engineering da University of New Brunswick, Canadá. Os ensaios tiveram como objetivo comparar as medidas de dois instrumentos geotécnicos convencionais, transdutor de deslocamento e acelerômetro, com as medidas obtidas por meio de receptores GPS de uma freqüência, L1. A comparação com o transdutor de deslocamento foi realizada em uma passarela de madeira, medindo-se a amplitude e freqüência dos seus deslocamentos dinâmicos, induzidos pelo caminhar de pedestres. A comparação com o acelerômetro consistiu em aplicar um deslocamento periódico vertical nos instrumentos por meio de um oscilador eletromecânico. Os dados do GPS foram obtidos pelo Método dos Resíduos de Fase (MRF). Como este método não necessita do uso de coordenadas conhecidas é muito prático para medidas de oscilações de amplitude milimétrica. As análises dos resultados obtidos pelos diferentes instrumentos permitem indicar precisão e acurácia das medidas realizadas com o GPS

Driver Behavioral Classification on Curves Based on the Relationship between Speed, Trajectories, and Eye Movements: A Driving Simulator Study

Horizontal curves of rural highways are prone to a considerably high number of fatalities because an erroneous perception can lead to unsafe driving. This generally occurs when a driver fails to notice the highway geometry or changes in the driving environment, particularly curved segments. This study aimed to understand the geometric characteristics of curved segments, such as radius and approach tangents, on the driving performance towards minimizing vehicle crashes. Speed profiles and lateral position, the most common indicators of successful negotiation in curves, and eye movements were recorded during an experiment conducted in a fixed-base driving simulator equipped with an eye-tracking system with a road infrastructure (a three-lane highway) and its surroundings. A driving simulator can faithfully reproduce any situation and enable sustainable research because it is a high-tech and cost-effective tool allowing repeatability in a laboratory. The experiment was conducted with 28 drivers who covered approximately 500 test kilometers with 90 horizontal curves comprising nine different combinations of radii and approach tangent lengths. The drivers’ behavior on each curve was classified as ideal, normal, intermediate, cutting, or correcting according to their trajectories and speed changes for analyses of the performance parameters and their correlation conducted by factorial ANOVA and Pearson chi-square tests. The cross-tabulation results indicated that the safest behavior significantly increased when the curve radius increased, and the performance measures of curve radii were greatly affected. However, the driving behavior was not affected by the approach tangent length. The results revealed segments of the road that require a driver’s closer attention for essential vehicle control, critical information, and vehicle control in different parts of the task

Effects of Fog in a Brazilian Road Segment Analyzed by a Driving Simulator for Sustainable Transport: Drivers’ Visual Profile

Visibility is a critical factor for drivers to perceive roadway information, and fog is an inclement weather condition that directly impacts their vision, since it reduces both overall contrast and visibility of the driving scene. Visual attention has been considered a contributing factor to traffic crashes, and fog-related accidents are prone to be more severe and involve multiple vehicles. The literature lacks studies on the influence of fog on drivers’ visual performance and environment’s infrastructure design. This article investigates the effects of fog on drivers’ performance in a Brazilian curved road segment through a driving simulator experiment – more precisely, whether the presence of fog (foggy scenario) or its absence (clear scenario) significantly affects the visual profile. In the foggy scenario, the results showed the tracked area was concentrated in a smaller region, despite an increase in the number of fixations compared with the clear scenario. The fixation duration did not change between the scenarios and the pupil dilation was shorter in the foggy one. The study shows the influence of environmental conditions on the driver’s performance and is one of the first on the use of driving simulators with realistic representations of the road infrastructure and its surrounding for the understanding of driving under fog in the Brazilian scenario. Besides roadway geometry elements, driving simulator studies enable analyses of features related to the interaction between route environment and driver’s answer, and can improve safety in places with visibility problems caused by fog, reducing their environmental impact and preserving drivers’ lives

Driver Behavioral Classification on Curves Based on the Relationship between Speed, Trajectories, and Eye Movements: A Driving Simulator Study

Horizontal curves of rural highways are prone to a considerably high number of fatalities because an erroneous perception can lead to unsafe driving. This generally occurs when a driver fails to notice the highway geometry or changes in the driving environment, particularly curved segments. This study aimed to understand the geometric characteristics of curved segments, such as radius and approach tangents, on the driving performance towards minimizing vehicle crashes. Speed profiles and lateral position, the most common indicators of successful negotiation in curves, and eye movements were recorded during an experiment conducted in a fixed-base driving simulator equipped with an eye-tracking system with a road infrastructure (a three-lane highway) and its surroundings. A driving simulator can faithfully reproduce any situation and enable sustainable research because it is a high-tech and cost-effective tool allowing repeatability in a laboratory. The experiment was conducted with 28 drivers who covered approximately 500 test kilometers with 90 horizontal curves comprising nine different combinations of radii and approach tangent lengths. The drivers’ behavior on each curve was classified as ideal, normal, intermediate, cutting, or correcting according to their trajectories and speed changes for analyses of the performance parameters and their correlation conducted by factorial ANOVA and Pearson chi-square tests. The cross-tabulation results indicated that the safest behavior significantly increased when the curve radius increased, and the performance measures of curve radii were greatly affected. However, the driving behavior was not affected by the approach tangent length. The results revealed segments of the road that require a driver’s closer attention for essential vehicle control, critical information, and vehicle control in different parts of the task

Study of Influence of Barriers on Visibility of Two-Way Highways

Stopping Sight Distance (SSD) must be guaranteed the entire length of a highway. However, elements of the cross-section in the design can interfere with sight distances. This can be the case when barriers, rather than medians, are used on two-way highways, especially along left curves. Thus, this study analyzed the position of barriers in a hypothetical scenario using graphic three-dimensional simulations. The lateral offset of the barrier relative to the roadway was defined according to each design speed and radius of the horizontal curve was analyzed. The results of the simulation were compared with the model, which was found in Brazilian guides, for offsetting fixed objects from horizontal curves. The differences found in this study demonstrated the viability of the method used, and the project was considered useful as a whole because it was developed in a three-dimensional fashion

Analyzing the Dynamic Behavior of Suspension Bridge Towers Using GPS

ABSTRACT The aim of this work is to characterize the dynamic oscillation of the top of the towers of a suspension bridge with GPS and to analyze the resulting values by Fourier analysis and wavelet transform. It is a complementary research about the analysis of the dynamic movements of the Pierre-Laporte Suspension Bridge in Quebec City, Canada. A previous work [Larocca et al., 2005b] analyzed the deck's movements of this bridge. Suspension bridge fundamentally consists of cables anchored to the earth at their ends and supported by towers at intermediate points. From these cables, a floor or 'deck' is suspended. Therefore, the towers have to be flexible enough to allow for changes in length due to live loads and temperature. Theoretically, the tower can be assumed as a thin beam. GPS data were collected at the towers of the bridge. The data sets were collected by researchers from the Centre de Recherché en Géomatique at Université Laval in July 1996. One GPS receiver was installed on the top of each of the towers, both 110 m in height, whereas a third receiver was placed on the ground, used as reference. Two 3-hour GPS sessions with a data-sampling interval of 2 seconds were collected. As no other sensors were used for measuring the deflections, the conclusions about the results are supported by theoretical values