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O desenvolvimento de novas técnicas de dimensionamento, construção e gerência de pavimentos requer o conhecimento dos efeitos dinâmicos da interação veículo-via, que dependem da irregularidade longitudinal do pavimento e de fatores associados ao veículo, como o espaçamento entre eixos, a velocidade de operação, caraterísticas de suspensão, a pressão de enchimento dos pneus e o tipo de rodagem dos eixos traseiros (rodagem dupla ou simples). Esta pesquisa tem por objetivo principal a quantificação das solicitações dinâmicas de veículos rodoviários de carga sobre os pavimentos, mediante utilização do programa computacional TruckSim e visa a quantificação dos efeitos dos fatores carga por eixo, tipo de veículo, velocidade dos veículos e irregularidade longitudinal sobre o desempenho dos pavimentos. Os resultados mostram que os efeitos dinâmicos, particularmente quando os pavimentos estão em condição ruim (IRI superior a 4), têm potencial de intensificar as forças atuantes na via em até 280%, considerando-se um excesso de carga de 7,5%, que é a tolerância estabelecida pela legislação brasileira, e que, de uma maneira global, podem reduzir a vida em serviço de um pavimento em até 87%. / The development of new techniques for design, construction and management of pavements requires the knowledge of the dynamic effects associated to vehicle-track interactions, which depends on the pavement roughness and vehicle characteristics, such as the spacing between axles, the operational speed, characteristics of suspension, the tire inflation pressure and wheel type of rear axle (dual or single). The main goal of this research is quantifying the dynamic stresses of road freight vehicles on the pavements, by using the computer program TruckSim, and aims to quantify the effects of the factors: axle load, vehicle type, vehicle speed and longitudinal roughness on the pavement performance. The results show that the dynamic effects, particularly when the pavements are in poor condition (IRI greater than 4), have the potential to intensify the forces acting on the road up to 280%, considering an overload of 7.5%, which is the tolerance established by Brazilian law, and that in global effects it can reduce the service-life of a pavement up to 87%.

O desenvolvimento de novas técnicas de dimensionamento, construção e gerência de pavimentos requer o conhecimento dos efeitos dinâmicos da interação veículo-via, que dependem da irregularidade longitudinal do pavimento e de fatores associados ao veículo, como o espaçamento entre eixos, a velocidade de operação, caraterísticas de suspensão, a pressão de enchimento dos pneus e o tipo de rodagem dos eixos traseiros (rodagem dupla ou simples). Esta pesquisa tem por objetivo principal a quantificação das solicitações dinâmicas de veículos rodoviários de carga sobre os pavimentos, mediante utilização do programa computacional TruckSim e visa a quantificação dos efeitos dos fatores carga por eixo, tipo de veículo, velocidade dos veículos e irregularidade longitudinal sobre o desempenho dos pavimentos. Os resultados mostram que os efeitos dinâmicos, particularmente quando os pavimentos estão em condição ruim (IRI superior a 4), têm potencial de intensificar as forças atuantes na via em até 280%, considerando-se um excesso de carga de 7,5%, que é a tolerância estabelecida pela legislação brasileira, e que, de uma maneira global, podem reduzir a vida em serviço de um pavimento em até 87%. / The development of new techniques for design, construction and management of pavements requires the knowledge of the dynamic effects associated to vehicle-track interactions, which depends on the pavement roughness and vehicle characteristics, such as the spacing between axles, the operational speed, characteristics of suspension, the tire inflation pressure and wheel type of rear axle (dual or single). The main goal of this research is quantifying the dynamic stresses of road freight vehicles on the pavements, by using the computer program TruckSim, and aims to quantify the effects of the factors: axle load, vehicle type, vehicle speed and longitudinal roughness on the pavement performance. The results show that the dynamic effects, particularly when the pavements are in poor condition (IRI greater than 4), have the potential to intensify the forces acting on the road up to 280%, considering an overload of 7.5%, which is the tolerance established by Brazilian law, and that in global effects it can reduce the service-life of a pavement up to 87%.

Roadway grades have a diverse effect on vehicle speeds, depending on vehicle and roadway characteristics. For example, passenger cars can generally negotiate grades of 5 percent or less without considerable reductions in vehicle speeds, while heavy-duty trucks are affected significantly by grades because of their inferior operating capability. Consequently, due to the potential significant speed differential between automobiles and heavy-duty trucks, these trucks can have a significant impact on the quality of flow, throughput, and safety of a traffic stream. Truck climbing lanes are typically constructed in an attempt to lessen this negative impact. Currently, the American Association of State Highway and Transportation Officials (AASHTO) and Highway Capacity Manual (HCM) represent the state-of-art and state-of-practice procedures for the design of truck climbing lanes. These procedures only consider the tangent vertical profile grades in the design of climbing lanes and do not capture the impact of vertical curvature on truck performance. The dissertation describes the TruckSIM framework for modeling vehicle motion along roadway sections by considering both the longitudinal and lateral forces acting on a vehicle. In doing so, the tool reflects the impact of horizontal and vertical alignment on a vehicle's longitudinal motion. The model is capable of reading Global Positioning System (GPS) (longitude, latitude, and altitude), roadway, and vehicle data. The dissertation demonstrates the validity of the software modeling procedures against field data and the HCM procedures. It is anticipated that by automating the design procedures and considering different vehicle and roadway characteristics on truck motion, the TruckSIM software will be of considerable assistance to traffic engineers in the design of roadways. The Global Positioning System (GPS) was originally built by the U.S. Department of Defense to provide the military with a super-precise form of worldwide positioning. With time, GPS units were introduced into the civilian domain and provided transportation professionals with an opportunity to capitalize on this unique instrumentation. With this GPS capability, this research investigates the feasibility of using inexpensive WAAS-capable units to estimate roadway vertical and horizontal profiles. The profiles that are generated by these inexpensive units (less than $500) are compared to the profiles generated by expensive carrier-phase DGPS units ($30,000 per unit including the base station). The results of this study demonstrate that the use of data smoothing and stacking techniques with the WAAS data provides grade estimates that are accurate within 10% of those generated by the carrier-phase DGPS units and thus offer a cost effective tool for providing input data to the TruckSIM software. Using the TruckSIM software, this research effort investigates truck performance reflective of various truck and road characteristics. These characteristics include vehicle engine power, weight-to-power ratio, pavement type, pavement condition, aerodynamic aid features, engine efficiency, tire type, and percentage mass on tractive axle. The study demonstrates that the vehicle weight-to-power ratio, vehicle engine power, pavement surface condition, tire type, aerodynamic aids, and engine efficiency are critical factors in the design of truck climbing lanes. / Ph. D.

The objective of this research is to develop a customized hardware-in-the-loop system that is used to test Electronic Stability Program (ESP) systems to prevent heavy truck rollovers when navigating horizontal roadway curves. While most of the published literature on electronic stability control focuses on the effectiveness of stability systems in passenger cars, very few researchers have considered its application as it pertains to commercial vehicles. Detailed crash data that have been extracted from the crashes that are represented in the Large Truck Crash Causation Study database have been used to draw conclusions regarding the main cause of the crashes and the geometry of the road upon which the crashes occurred. Those crash scenarios were run through a hardware-in-the-loop system that communicates between the TruckSim software, a vehicle dynamics based simulation program, and a real-time tractor-trailer braking rig. The simulations were first run without the ESP enabled to determine the critical speed which will cause the truck to roll, then the same simulation runs were executed with the Bendix stability system enabled to determine the difference in speeds in which a rollover is inevitable with and without the technology. A third speed that represents the lowest speed in which the stability system activates was also determined. As requested by the National Highway Traffic Safety Administration (NHTSA), this study also serves as a comparison between the Bendix system and the Meritor WABCO system which has already been tested by the University of Michigan Transportation Research Institute. / Master of Science

This research presents an investigation to actively improve the rollover stability of articulated heavy vehicles (AHVs) during high speed manoeuvres using anti-roll control systems. A 3-dimensional (3-D) linear yaw/roll model with 5 degrees of freedom is developed. Based on this model a linear quadratic regulator (LQR) controller is designed to improve the rollover stability of a tractor/semi-trailer combination. A design optimization method for AHVs using genetic algorithms (GAs) and multibody vehicle system models is also presented. AHVs have poor manoeuvrability when travelling at low speeds on local roads and city streets. On the other hand, these vehicles exhibit unstable motion modes at high speeds, including jack-knifing, trailer sway and rollover. From the design point of view, the low-speed manoeuvrability and high-speed stability have conflicting requirements on some design variables. The design method based on a GA and a multibody vehicle dynamic package, TruckSim, is proposed to coordinate this trade-off relationship. To test the effectiveness of the design method, a tractor/semi-trailer combination is optimized using the proposed method. It is demonstrated that the proposed design method can be used for identifying desired design variables and predict performance envelopes in the early design stages of AHVs. / UOIT

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The use of global positioning systems, or GPS, as a means of logistical organization for fleet vehicles has become more widespread in recent years. The system has the ability to track vehicle location, report on diagnostic trouble codes, and keep tabs on maintenance schedules. This helps to improve the safety and productivity of the vehicles and their operators. Additionally, the increasing use of yaw and roll stability control in commercial trucks has contributed to an increased level of safety for truck drivers. However, these systems require the vehicle to begin a yaw or roll event before they assist in maintaining control. This thesis presents a new method for utilizing the GPS signal in conjunction with a new fuzzy logic-based stability index, the Total Safety Margin (TSM), to create a superior active safety system. This thesis consists of four main components: An overview of GPS technology is presented with coverage of several automotive-based applications. The proposed implementation of GPS in the new Hardware-in-the-Loop (HIL) driving simulator under development at the Virginia Tech Center for Vehicle Systems and Safety (CVeSS) is presented. The three degree-of-freedom (3DOF), linear, single track equation set used in the Matlab simulations is derived from first principles. Matlab and TruckSim 7® simulations are performed for five vehicle masses and three forward velocities in a ramp-steer maneuver. Using fuzzy logic to develop the control rules for the Total Safety Margin (TSM), TSM matrices are built for both the Matlab and TruckSim 7® results based on these testing conditions. By comparing these TSM matrices it is shown that the two simulation methods yield similar results. A discussion of the development and implementation of the aforementioned HIL driving simulator is presented, specifically the steering subsystem. Using Matlab/Simulink, dSPACE ControlDesk, and CarSim RT® software it is shown that the steering module is capable of steering the CarSim RT® simulation vehicle accurately within the physical range of the steering sensor used. / Master of Science

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