Driving a horizontal roadway curve requires a change in vehicle alignment and a potential reduction in speed. Curves may present a challenging situation during adverse conditions or to inattentive drivers. Chevron signs provide advanced warning and positive guidance throughout the curve. Some agencies place supplemental retroreflective material on sign posts to enhance the signs? conspicuity and visibility. The objective of this study was to determine any incremental benefits in vehicle speed and lateral lane position when retroreflective material was applied to Chevron sign posts (ChevFull). This study analyzed three separate evaluation scenarios in a before, after, and after-after experimental design. There was an existing Baseline evaluation with no vertical delineation, a standard Chevron evaluation, and an experimental ChevFull treatment evaluation. Data collection measured vehicle speed and lateral position data at the point of curvature and mid-point on two separate curves. Findings showed that both Chevrons and the ChevFull treatment moved vehicles away from oncoming traffic by about 15 inches. Overall, there was little difference between the lateral position findings of the two Chevron treatment scenarios. Chevrons achieved a 1.28 MPH reduction in mean vehicle speed from the Baseline evaluation and the ChevFull treatment obtained a 2.20 MPH reduction. The findings determined that the benefits of the ChevFull treatment were not substantial. The author recommends that the MUTCD should continue to present the ChevFull treatment as an optional delineation tool. Based on this research, the author does not recommend any changes to the MUTCD.

This thesis documents the linear mixed model developed for vehicle speed along two-lane two-way rural horizontal curves in the outside lane. Speed data at each curve was collected at four points along the curve including the midpoint of the curve for a minimum of 48 hours during weekdays. Vehicle speed was analyzed separately for day and night conditions. The horizontal curves were categorized into different groups using different methods using side friction demand, radius and pavement edgeline marking retroreflectivity. In the speed prediction model, radius, superelevation at the midpoint of the curve, deflection angle, posted speed limit and pavement edgeline marking retroreflectivity were used to predict the vehicle speed at the midpoint of the horizontal curve. The regression analysis indicates that all of these variables are statistically significant in predicting the vehicle speed at the midpoint of horizontal curves with a 95 percent confidence interval. The linear model determined that the vehicle speed has a positive relation with the radius of the curve, superelevation and posted speed limit but has a negative relation with the deflection angle and pavement edgeline marking retroreflectivity. Curves were categorized based on side friction demand or radius and retroreflectivity of pavement edgeline marking. ANOVA was used to compare the day and night time speed. The comparisons reveal that vehicle speed at the horizontal curves decreases as the side friction demand value of the curves increases. Another finding of this research was that even though the posted speed limit is incorporated into the calculation of side friction demand, it may be necessary to analyze the impact of posted speed limit on vehicle speed for both daytime and nighttime. Previous literature determined that drivers may drive at an unsafe speed during nighttime at high levels of retroreflectivity. The results of this study could not confirm this statement as data from this study suggests that for curves with pavement edgeline marking retroreflectivity greater than 90 mcd/m2/lx, the effects of retroreflectivity on speed was determined to be minimal. This is based on the finding that the daytime and nighttime speeda were basically the same as the daytime and nighttime speed difference was both statistically and practically insignificant.

This diploma thesis deals with relation between car velocity and the impacts od traffic accidents. The basic keywords are described in the first part of the thesis and legislative regulations follow in the second chapter. The third and the fourth chapters introduce particular sanctions and statistics concerning the Czech Republic and they are compared to foreign countries. The influence of active safety on traffic accidents consequences is solved in the next part of the thesis. Subsequent figures and tables containing diffrent parametres are provided to demonstrate the relations between various crash car speed and particular braking distances. The tables also present mutual relations between rising initial velocity and changes in a numbers. The seventh chapter analyses a few selected case studies of real accidents and the final chapter focuses on individual relations between velocity and its impacts.

According to the US Department of Transportation, around 20 people die on a daily basis in a signalized intersection, with most of these resulting from angle or head-on collisions. The US-DoT’s Federal Highway Administration (FHWA) has identified modern roundabout intersections to be substantially safer than signalized intersections, due in part to the reduction in conflict points from 32 in a traditional signalized intersection to 8 in a modern roundabout. Despite the increased adoption of modern roundabouts across the US, there are a number of specific design elements for which the direct impact they have on operational and safety related performance of the roundabout remains unknown. To be specific, there is currently no conclusive research on the direct effects related to the introduction of a reverse curve (S-curve) on the approach to a roundabout. Moreover, what are the impacts of S-curves of varying geometries on the approach to a roundabout? This research employed a series of microsimulation-based analyses to investigate the speed related impacts related to the introduction to S-curves on the entry to a roundabout. An existing roundabout, in Amherst, MA, USA was used as a case study for this experiment. The data at each approach of the roundabout was collected by a static camera strategically placed to attain both the pedestrian and vehicle count during peak traffic hours. The data was manually reviewed to determine the upstream and downstream vehicle counts. The dimensions and angles of the existing roundabout were measured from Google earth and the image was extracted to AutoCaD Civil 3D. Since the objective is to check whether S-curves near an approach have a significant impact in speed, the deflection angle of the roundabout was not altered. The turning radius and angle at the approach was cross verified by measuring it on site. The existing roundabout was considered as the base model. The four approaches of the roundabout have different entry angles and radii. The revised models were drafted by strategically placing the S-curve at each approach and by steadily increasing their deflection angle and approach radius. The base and revised models cases were initially modelled, after which the conventional linear approach was modified to an S-curve and evaluated. Field data from the locations were to and calibrate microsimulation models on AIMSUN. The resulting trajectory data was analyzed for both the base case as well as three levels of experimental S-curves (ranging from 30 to 60 degrees) on each roundabout approach (16 total). The results provide evidence to suggest that a significant reduction in speed can be realized with a minimal amount of the reverse curvature on the roundabout approach. The trajectory output files were then imported into the Surrogate Safety Assessment Model (SSAM) to determine the number and type of conflicts experienced at each approach under each scenario evaluated in AIMSUN.

The diploma thesis deals with the issue of driver´s subjective estimation of vehicle speed and at the same time it is a project dealing with acquisition and evaluation of data obtained during the driving tests. The perceived vehicle speed is examined from the perspective of a driver - the respondent, who has no possibility of controlling the actual vehicle speed on the vehicle's speedometer. The aim is to either confirm or refute whether the driver is able to adequately estimate the speed of a moving vehicle in the event of an accident as well as describe the factors that may affect a subjective estimation of the driver's speed.

This master’s thesis deals with the issue of the perception of speed of a vehicle from pedestrian’s point of view. The theoretical part consists of a research into sense perception of humans and construction of motor vehicles. The practical part designs and describes the experiment which was performed in order to provide data used for analyzing different factors and their effect on the accuracy of vehicle speed estimations.

No description available.

Esta dissertação tem como objetivo estudar um método para estimar a velocidade de veículos ferroviários usando processamento de vídeo. O sistema proposto consiste na utilização de câmeras ao longo das vias férreas que permitam não só o monitoramento do tráfego ferroviário, mas cujo vídeo captado possa ser utilizado para a obtenção de estimativas para a velocidade instantânea dos trens que por ela trafegam. Tal sistema seria utilizado independentemente dos sistemas de controle já utilizados pela operadora do sistema ferroviário, permitindo que os controladores possam ter uma segunda análise no caso de falha da primeira, assim como um modelo que permita avaliar a velocidade instantânea do veículo ferroviário ao longo do percurso. Os algoritmos de rastreamento empregados para esse fim abordaram diferentes métodos. Confrontaram-se os resultados obtidos com os algoritmos propostos com os dados empíricos de forma a determinar aquele com melhor resposta dada as características do sistema. O algoritmo que apresentou os melhores resultados emprega um único bloco de referência para todos os quadros comparados. A métrica de similaridade responsável por determinar quais blocos são mais ou menos similares dentro do universo de busca estipulado é a soma de diferenças absolutas (SAD, Sum of Absolute Differences). O tempo de processamento requerido por cada um dos métodos de rastreamento estudados também foi considerado nas avaliações de resultados apresentadas. Uma comparação realizada entre as velocidades coletadas e aquelas informadas pelo sistema de controle mostraram que os resultados obtidos com o sistema atual, utilizando a sinalização apenas por circuito de via apresenta resultados pouco confiáveis com erros bastante significativos. Os resultados obtidos com o sistema proposto apresentaram erros menores quando comparados àqueles obtidos pelo sistema vigente, apresentando-se assim como uma solução viável e de baixo custo quando comparada às técnicas atualmente empregadas para a medida de velocidade de trens. / This dissertation aims to study a method of estimating the speed of railway vehicles using video processing. The proposed system uses cameras disposed alongside railways to monitor traffic as well as estimate train speeds. Such a system would allow the machinist to have a backup control system, regardless of the control systems already used by the operator of the rail system. In this dissertation, tracking algorithms with different methods are discussed. By comparing results obtained with the proposed algorithm and results from empirical data, it was possible to determine the one that best provided the desired results given the characteristics of the system. The algorithm which presented the best results was the one that employs a single block for all reference frames compared. The metric of similarity used for determining which blocks are most similar within the searched universe is the sum of absolute differences (SAD). The processing time required by each of the screening methods studied was also considered in assessing the results presented. A comparison between the rates collected and those informed by the control system showed that the results obtained with the current system, which only uses the signal track circuit, provides unreliable results with very significant errors. The results obtained with the proposed system had errors smaller than those obtained with the current system, suggesting the proposed system is viable and cost-effective compared to currently employed techniques.

Esta dissertação tem como objetivo estudar um método para estimar a velocidade de veículos ferroviários usando processamento de vídeo. O sistema proposto consiste na utilização de câmeras ao longo das vias férreas que permitam não só o monitoramento do tráfego ferroviário, mas cujo vídeo captado possa ser utilizado para a obtenção de estimativas para a velocidade instantânea dos trens que por ela trafegam. Tal sistema seria utilizado independentemente dos sistemas de controle já utilizados pela operadora do sistema ferroviário, permitindo que os controladores possam ter uma segunda análise no caso de falha da primeira, assim como um modelo que permita avaliar a velocidade instantânea do veículo ferroviário ao longo do percurso. Os algoritmos de rastreamento empregados para esse fim abordaram diferentes métodos. Confrontaram-se os resultados obtidos com os algoritmos propostos com os dados empíricos de forma a determinar aquele com melhor resposta dada as características do sistema. O algoritmo que apresentou os melhores resultados emprega um único bloco de referência para todos os quadros comparados. A métrica de similaridade responsável por determinar quais blocos são mais ou menos similares dentro do universo de busca estipulado é a soma de diferenças absolutas (SAD, Sum of Absolute Differences). O tempo de processamento requerido por cada um dos métodos de rastreamento estudados também foi considerado nas avaliações de resultados apresentadas. Uma comparação realizada entre as velocidades coletadas e aquelas informadas pelo sistema de controle mostraram que os resultados obtidos com o sistema atual, utilizando a sinalização apenas por circuito de via apresenta resultados pouco confiáveis com erros bastante significativos. Os resultados obtidos com o sistema proposto apresentaram erros menores quando comparados àqueles obtidos pelo sistema vigente, apresentando-se assim como uma solução viável e de baixo custo quando comparada às técnicas atualmente empregadas para a medida de velocidade de trens. / This dissertation aims to study a method of estimating the speed of railway vehicles using video processing. The proposed system uses cameras disposed alongside railways to monitor traffic as well as estimate train speeds. Such a system would allow the machinist to have a backup control system, regardless of the control systems already used by the operator of the rail system. In this dissertation, tracking algorithms with different methods are discussed. By comparing results obtained with the proposed algorithm and results from empirical data, it was possible to determine the one that best provided the desired results given the characteristics of the system. The algorithm which presented the best results was the one that employs a single block for all reference frames compared. The metric of similarity used for determining which blocks are most similar within the searched universe is the sum of absolute differences (SAD). The processing time required by each of the screening methods studied was also considered in assessing the results presented. A comparison between the rates collected and those informed by the control system showed that the results obtained with the current system, which only uses the signal track circuit, provides unreliable results with very significant errors. The results obtained with the proposed system had errors smaller than those obtained with the current system, suggesting the proposed system is viable and cost-effective compared to currently employed techniques.

M. Tech. (Information Technology, Faculty of Applied and Computer Sciences), Vaal University of Technology / Traffic congestion is a concern within the main arteries that link Johannesburg to Pretoria. In this study Matlab function Randperm is used to generate random vehicle speeds on a simulated highway. Randperm is used to mimic vehicle speed sensors capturing vehicle traffic on the highway. Java sockets are used to send vehicle speed to the Road Traffic Control Centre (RTCC)-database server through a wireless medium. The RTCC-database server uses MySQL to store vehicle speed data. The domain controller with active directory together with a certificate server is used to manage and provide security access control to network resources. The wireless link used by speed sensors to transmit vehicle speed data is protected using PEAP with EAP-TLS which employs the use of digital certificates during authentication. A java database connectivity driver is used to retrieve data from MySQL and a multilayer perceptron (MLP) model is used to predict future traffic status on the highway being monitored i.e. next 5 minutes from previous 5 minutes captured data. A dataset of 402 instances was divided as follows: 66 percent training data was used to train the MLP model, 15 percent data used during validation and the remaining 19 percent was used to test the trained MLP model. An excel spreadsheet was used to introduce novel (19 percent data not used during training) data to the trained MLP model to predict. Assuming that the spreadsheet data represent captured highway vehicle data for the last 5 minutes, the model showed 100 percent accuracy in predicting the four classes: congested, out congested, into congested and normal traffic flow. Predicted traffic status is displayed for the motorist on the highway to know. Ability of the proposed model to continuously capture the traffic pattern on the highway (monitor) helps in redirecting (controlling) the highway traffic during periods of congestion. Implementation of this project will definitely decrease traffic congestion across main arteries of Johannesburg. Pollution normally experienced when cars idle for a long time during congestion will be reduced by free highway traffic flow. Frequent servicing of motor vehicles will no longer be required by the motorists. Furthermore the economy of Gauteng and South Africa as a whole will benefit due to increase in production. Consumers will also benefit in obtaining competitive prices from organizations that depend on haulage services.