Weigh-in-Motion (WIM) systems have improved the process of collecting data from heavy vehicles on the U.S. highway system and enforcing the laws that govern vehicle weights. The benefits of WIM are reaped by everyone from highway designers and voernments officials, to truck drivers and transportation industry owners. The data collected by WIM devices is essential for proper pavement design, developing pavement management systems, weight enforcement strategies, modeling traffic improvement projects, and predicting load-related distresses and performance. While WIM offers many advantages over its alternative, static weighing, the technology is limited by problems associated with the accuracy of its measurements. Weigh-in-Motion systems that lack accuracy require vehicles to travel slower and can result in higher queues, longer delays, and potential hazards. For these reasons, WIM system performance must be improved in order to adequately serve its purpose. In order to evaluate WIM system performance and determine what vehicle characteristics have the most affect on it, two systems in the Commonwealth of Virginia were evaluated. The first system was an in-service WIM system at the Troutsville weigh station on I-81. The Troutsville station had bending plate WIM scales located in both the northbound and southbound directions. The second system in a newly developed WIM system manufactured by Omni Weight Corporation (OWC) and was installed at the Virginia Smart Road for evaluation. The OWC scale is a completely sealed and buried system that has ten strain gauge sensors in its interior. Evaluation of both scales was performed by conducting a number of test runs under varying load conditions. Testing at Troutsville was performed using four different test vehicles with multiple loads on each. Variation in load was achieved by loading the test vehicles with various numbers of concrete Jersey Walls. Testing on the OWC scale was performed using only two test vehicles while varying the speed, load, tire pressure, and direction of travel over the scale. The study showed that the scales at the Troutsville weigh station yielded 10% error or less on only 77% of the tests, not complying with the required 95% set forth by ASTM E-1318. In comparison, using the manufacturer's processed data for the OWC scale yielded only 18% of its tests with 10% error or less, far below the ASTM standard. A model was developed to re-calculate the axle weights using the raw sensor data from the OWC scale; and an evaluation of the accuracy of this data showed that the OWC scale performed much better. While compliance with the ASTM standards was still not achieved, it rose from 18% to 71% of the tests having 10% error or less. Repeatability of the Troutsville scales and OWC scales was found to be comparable. / Master of Science

Weigh-in-Motion (WIM) systems improve the capacity of weigh station operations significantly by screening trucks while traveling at high speeds and only requiring trucks within a threshold of a maximum permissible gross of axle weight to be weighed on more accurate static scales. Consequently, the operation of a weigh station is highly dependent on the accuracy of the screening WIM system. This thesis develops a procedure for relating axle accuracy to gross vehicle accuracy and develops a field and modeling framework for evaluating weigh station operations. The WIM scale operation at the Stephens City weigh station in Virginia is examined to demonstrate how the field and modeling framework can be applied to evaluate the operation of a weigh station. Specifically, the field evaluation evaluated the accuracy of the WIM technology in addition to the operations of the weigh station in terms of service time, system time, and delay incurred at the static scales. During the field evaluation of the Stephens City WIM load cell system, the WIM technology was found to estimate truck weights to within 6 and 7 percent of the static weights 95 percent of the time. The modeling framework provides a methodology that can be used to determine the effects of the truck demand, the WIM accuracy, the system threshold, and the WIM calibration on system performance. The number of vehicles sent to the static scale and bypass lanes as well as the amount of delay experienced were analyzed for various system characteristics. The proposed framework can be utilized to estimate vehicle delay at a weigh station. / Master of Science

Traffic load model in standard or specification for bridge design should guarantee all newly designed bridges to have sufficient security margin for future traffic. Many different methods have been used to model extreme traffic load effects on bridges for predicting characteristic value for short or long return period. In order to provide some guidance on selecting parameter estimation when applying POT to bridge traffic loading, we focus on the effect that method used to estimate the parameters of the GPD has on the accuracy of the estimated characteristic values. Through this qualitative discussion on the methods, several available methods for traffic loading are selected. Numerical simulation data, Monte Carlo simulation traffic load effects and in-field traffic load effect measurements are analyzed and presented. Literature points out that the traffic load effect is induced by loading event that involves different number of vehicles, and the distribution of the load effects from different loading events are not identically distributed, which violates the assumption of classic extreme value theory that the underlying distribution should be identically independent distributed. Methods using mixture distribution (exponential or generalized extreme value) has been proposed in the literature to model the extreme traffic load effect by loading event. However, the traffic loading may be also importance if the bridge encounter traffic induced fatigue problem, components like orthotropic steel deck is governed by traffic induced fatigue load effects. We intend to explore the influence of traffic load on the fatigue behaviour of orthotropic steel deck, especially the influence of the loading position in terms of transverse location of vehicle. Measurements of transverse location of vehicle collected from by weigh-in-motion (WIM) systems in 2010 and 2011 four French highways showed a completely different distribution model of transverse location of vehicle to that recommended in EC1. Stress spectrum analysis and fatigue damage calculation was performed on the stresses induced traffic on orthotropic steel deck of Millau cable-stayed bridge. By comparing the stresses and damages induced by different traffic patterns (through distributions of transverse location of vehicle), it was found that the histogram of stress spectrum and cumulative fatigue damage were significantly affected by the distribution of transverse location of vehicle. Therefore, numerical analysis that integrates finite element modelling and traffic data with distributions of transverse location of vehicles can help to make an accurate predetermination of which welded connections should be sampled to represent the health of the deck

Este trabalho apresenta um estudo sobre o comportamento de sistemas de pesagem em movimento baseados em plataformas comumente utilizadas no Brasil. Parâmetros relevantes nesse comportamento são modelados: rugosidade aleatória da pista, dinâmica vertical do veículo e sua velocidade, desnível entre a pista e plataforma e dinâmica da plataforma. Duas classes de veículos são simuladas trafegando a diferentes velocidades e sendo pesados utilizando uma proposta de modelo de plataforma rígida e uma proposta de plataforma flexível. As forças de reação do solo e históricos de aceleração em vários GDL são registrados a fim de obter a carga estática por eixo e os erros nas estimativas do peso para o modelo de plataforma rígida. Já para o modelo de plataforma flexível, as forças de reação servem de entrada no modelo de elemento finitos de viga Euler-Bernoulli com consideração da área de contato do pneu através de um trem de cargas. Conclusões relacionadas à redução da precisão do sistema com o aumento da velocidade do veículo são confirmadas, embora importantes conclusões não tão óbvias sobre a importância da dinâmica do veículo, do nível de rugosidade da pista, da altura do degrau pista-plataforma e da dinâmica da plataforma de pesagem são ressaltadas. / This work proposes a numerical study on the behavior of weigh-in-motion systems based on load platforms useful in Brazil. Some important parameters that may control this behavior that are modeled are random road roughness, vehicle vertical dynamics, vehicle speed, load platform step’s height to the road and platform dynamics. Two vehicles types are modelled travelling at different speeds and being weighted using a rigid platform proposal and another proposal with a flexible platform. Ground reaction force and acceleration time history on several degree-of-freedom are recorded in order to obtain the static load per axis and the corresponding estimated errors for the rigid platform model. For the flexible platform model, the reaction forces serve as inputs into the Euler-Bernoulli finite element model with consideration of the contact area of the tire by train of loads. Some usual conclusions related to the reduction in the accuracy of the measuring system with increased vehicle speed are confirmed in the numerical study, although important conclusions not so obvious concerning the importance of road roughness, vehicle vertical dynamics, and vehicle speed, load platform step’s height to the road and platform dynamics are highlighted.

This research focuses on the data quality control methods for evaluating the performance of Weigh-In-Motion (WIM) systems on Oregon highways. This research identifies and develops a new methodology and algorithm to explore the accuracy of each station's weight and spacing data at a corridor level, and further implements the Statistical Process Control (SPC) method, finite mixture model, axle spacing error rating method, and data flag method in published research to examine the soundness of WIM systems. This research employs the historical WIM data to analyze sensor health and compares the evaluation results of the methods. The results suggest the new triangulation method identified most possible WIM malfunctions that other methods sensed, and this method unprecedentedly monitors the process behavior with controls of time and meteorological variables. The SPC method appeared superior in differentiating between sensor noises and sensor errors or drifts, but it drew wrong conclusions when accurate WIM data reference was absent. The axle spacing error rating method cannot check the essential weight data in special cases, but reliable loop sensor evaluation results were arrived at by employing this multiple linear regression model. The results of the data flag method and the finite mixed model results were not accurate, thus they could be used as additional tools to complement the data quality evaluation results. Overall, these data quality analysis results are the valuable sources for examining the early detection of system malfunctions, sensor drift, etc., and allow the WIM operators to correct the situation on time before large amounts of measurement are lost.

In the past, transportation related economic analysis has considered agency related costs only. However, transportation managers are moving towards more holistic economic analysis including road user and environmental costs and benefits. In particular, transportation air pollution is causing increasing harm to health and the environment. Transport managers are now considering related emissions in transport economical analyses, and have established strategies to help meet Kyoto Protocol targets, which specified a fifteen percent reduction in Canada's emissions related to 1990 levels within 2008-2012.<p>The objectives of this research are to model heavy vehicle emissions using a emissions computer model which is able to assess various transport applications, and help improve holistic economic transport modeling. Two case studies were evaluated with the model developed.<p>Firstly, the environmental benefits of deploying weigh-in-motion systems at weigh stations to pre-sort heavy vehicles and reduce delays were assessed. The second case study evaluates alternative truck sizes and road upgrades within short heavy oilfield haul in Western Canada. <p>The model developed herein employed a deterministic framework from a sensitivity analysis across independent variables, which identified the most sensitive variables to primary field state conditions. The variables found to be significant included idling time for the weigh-in-motion case study, road stiffness and road grades for the short heavy haul oilfield case study.<p>According to this research, employing WIM at weigh stations would reduce annual Canadian transportation CO₂ emissions by nearly 228 kilo tonnes, or 1.04 percent of the Canadian Kyoto Protocol targets. Regarding direct fuel savings, WIM would save from 90 to 190 million litres of fuel annually, or between $59 and $190 million of direct operating costs.<p>Regarding the short heavy oil haul case study, increasing allowable heavy vehicle sizes while upgrading roads could decrease the annual emissions, the fuel consumption, and their associated costs by an average of 68 percent. Therefore, this could reduce each rural Saskatchewan municipality's annual CO₂ emissions from 13 to 26.7-kilo tonnes, which translates to 0.06 and 0.12 percent of the Canadian Kyoto Protocol targets or between $544,000 and $ 1.1 million annually. <p>Based on these results, the model demonstrates its functionality, and was successfully applied to two typical transportation field state applications. The model generated emissions savings results that appear to be realistic, in terms of potential Kyoto targets, as well as users cost reductions and fuel savings.

In the past, transportation related economic analysis has considered agency related costs only. However, transportation managers are moving towards more holistic economic analysis including road user and environmental costs and benefits. In particular, transportation air pollution is causing increasing harm to health and the environment. Transport managers are now considering related emissions in transport economical analyses, and have established strategies to help meet Kyoto Protocol targets, which specified a fifteen percent reduction in Canada's emissions related to 1990 levels within 2008-2012.<p>The objectives of this research are to model heavy vehicle emissions using a emissions computer model which is able to assess various transport applications, and help improve holistic economic transport modeling. Two case studies were evaluated with the model developed.<p>Firstly, the environmental benefits of deploying weigh-in-motion systems at weigh stations to pre-sort heavy vehicles and reduce delays were assessed. The second case study evaluates alternative truck sizes and road upgrades within short heavy oilfield haul in Western Canada. <p>The model developed herein employed a deterministic framework from a sensitivity analysis across independent variables, which identified the most sensitive variables to primary field state conditions. The variables found to be significant included idling time for the weigh-in-motion case study, road stiffness and road grades for the short heavy haul oilfield case study.<p>According to this research, employing WIM at weigh stations would reduce annual Canadian transportation CO₂ emissions by nearly 228 kilo tonnes, or 1.04 percent of the Canadian Kyoto Protocol targets. Regarding direct fuel savings, WIM would save from 90 to 190 million litres of fuel annually, or between $59 and $190 million of direct operating costs.<p>Regarding the short heavy oil haul case study, increasing allowable heavy vehicle sizes while upgrading roads could decrease the annual emissions, the fuel consumption, and their associated costs by an average of 68 percent. Therefore, this could reduce each rural Saskatchewan municipality's annual CO₂ emissions from 13 to 26.7-kilo tonnes, which translates to 0.06 and 0.12 percent of the Canadian Kyoto Protocol targets or between $544,000 and $ 1.1 million annually. <p>Based on these results, the model demonstrates its functionality, and was successfully applied to two typical transportation field state applications. The model generated emissions savings results that appear to be realistic, in terms of potential Kyoto targets, as well as users cost reductions and fuel savings.

Este trabalho apresenta um estudo sobre o comportamento de sistemas de pesagem em movimento baseados em plataformas comumente utilizadas no Brasil. Parâmetros relevantes nesse comportamento são modelados: rugosidade aleatória da pista, dinâmica vertical do veículo e sua velocidade, desnível entre a pista e plataforma e dinâmica da plataforma. Duas classes de veículos são simuladas trafegando a diferentes velocidades e sendo pesados utilizando uma proposta de modelo de plataforma rígida e uma proposta de plataforma flexível. As forças de reação do solo e históricos de aceleração em vários GDL são registrados a fim de obter a carga estática por eixo e os erros nas estimativas do peso para o modelo de plataforma rígida. Já para o modelo de plataforma flexível, as forças de reação servem de entrada no modelo de elemento finitos de viga Euler-Bernoulli com consideração da área de contato do pneu através de um trem de cargas. Conclusões relacionadas à redução da precisão do sistema com o aumento da velocidade do veículo são confirmadas, embora importantes conclusões não tão óbvias sobre a importância da dinâmica do veículo, do nível de rugosidade da pista, da altura do degrau pista-plataforma e da dinâmica da plataforma de pesagem são ressaltadas. / This work proposes a numerical study on the behavior of weigh-in-motion systems based on load platforms useful in Brazil. Some important parameters that may control this behavior that are modeled are random road roughness, vehicle vertical dynamics, vehicle speed, load platform step’s height to the road and platform dynamics. Two vehicles types are modelled travelling at different speeds and being weighted using a rigid platform proposal and another proposal with a flexible platform. Ground reaction force and acceleration time history on several degree-of-freedom are recorded in order to obtain the static load per axis and the corresponding estimated errors for the rigid platform model. For the flexible platform model, the reaction forces serve as inputs into the Euler-Bernoulli finite element model with consideration of the contact area of the tire by train of loads. Some usual conclusions related to the reduction in the accuracy of the measuring system with increased vehicle speed are confirmed in the numerical study, although important conclusions not so obvious concerning the importance of road roughness, vehicle vertical dynamics, and vehicle speed, load platform step’s height to the road and platform dynamics are highlighted.

Este trabalho apresenta um estudo sobre o comportamento de sistemas de pesagem em movimento baseados em plataformas comumente utilizadas no Brasil. Parâmetros relevantes nesse comportamento são modelados: rugosidade aleatória da pista, dinâmica vertical do veículo e sua velocidade, desnível entre a pista e plataforma e dinâmica da plataforma. Duas classes de veículos são simuladas trafegando a diferentes velocidades e sendo pesados utilizando uma proposta de modelo de plataforma rígida e uma proposta de plataforma flexível. As forças de reação do solo e históricos de aceleração em vários GDL são registrados a fim de obter a carga estática por eixo e os erros nas estimativas do peso para o modelo de plataforma rígida. Já para o modelo de plataforma flexível, as forças de reação servem de entrada no modelo de elemento finitos de viga Euler-Bernoulli com consideração da área de contato do pneu através de um trem de cargas. Conclusões relacionadas à redução da precisão do sistema com o aumento da velocidade do veículo são confirmadas, embora importantes conclusões não tão óbvias sobre a importância da dinâmica do veículo, do nível de rugosidade da pista, da altura do degrau pista-plataforma e da dinâmica da plataforma de pesagem são ressaltadas. / This work proposes a numerical study on the behavior of weigh-in-motion systems based on load platforms useful in Brazil. Some important parameters that may control this behavior that are modeled are random road roughness, vehicle vertical dynamics, vehicle speed, load platform step’s height to the road and platform dynamics. Two vehicles types are modelled travelling at different speeds and being weighted using a rigid platform proposal and another proposal with a flexible platform. Ground reaction force and acceleration time history on several degree-of-freedom are recorded in order to obtain the static load per axis and the corresponding estimated errors for the rigid platform model. For the flexible platform model, the reaction forces serve as inputs into the Euler-Bernoulli finite element model with consideration of the contact area of the tire by train of loads. Some usual conclusions related to the reduction in the accuracy of the measuring system with increased vehicle speed are confirmed in the numerical study, although important conclusions not so obvious concerning the importance of road roughness, vehicle vertical dynamics, and vehicle speed, load platform step’s height to the road and platform dynamics are highlighted.

An existing analytical model, in use by Spoornet for the past two decades for calculating rail stresses on railway track, was revisited and improved. The model provided engineers with an easy-to-use program for evaluating track capacity and authorizing heavier loads on track. The model was modified to calculate rail and track component stresses more accurately. These modifications include the incorporation of current best practices and presentation of guidelines for the engineer on how to determine some input parameters which are normally difficult to obtain. Firstly it was determined which input parameters the model was the most sensitive to. Thereafter it was determined whether or not the correct information would generally be readily available for those sensitive parameters. The most sensitive parameters were further investigated and test results, as well as best practice analytical methods, were used to establish nominal input values and guidelines for determining such values. This research was necessary to establish whether or not the currently used analytical model still provided railway engineers with a useful tool and whether or not more modern and popular tools could validate or replace it. After some modifications to the analytical model, it was proved that it provides engineers with a suitably accurate tool for calculating rail and track component stresses, without the need to build time-consuming models of the track under investigation. It showed that the model, after some modifications, is current with calculational methods in recent publications and provides an immediate answer to "what-if" questions without the need to run lengthy analyses. / Dissertation (MEng (Mechanical Engineering))--University of Pretoria, 2006. / Mechanical and Aeronautical Engineering / unrestricted