No description available.

No description available.

No description available.

No description available.

No description available.

Potholes are caused by erosion and as such always emerging on our roadnetwork. Potholes may not only cause great damages to vehicles, but can alsocause road accidents, which in the worst case are fatal. Today, the detection ofpotholes is usually based on citizen reports or ocular inspection by vehicle,where a loose description of the potholes properties and location can be given.Recent research has explored the possibility of aerial inspection of paved roadswith the new, cost effective, Structure-from-Motion (SfM) technique, whichcan produce 3D point clouds from photogrammetric data. SfM point cloudshave then been used in conjunction with processing algorithms toautomatically detect and extract potholes from paved surfaces. However, theresults have not been optimal for practical use. The purpose of this study is,therefore, to explore the possibility of using UAV LiDAR for potholedetection in paved roads as a better alternative to the currently popularStructure-from-Motion (SfM) technique. A LiDAR point cloud is derived by alaser scanner and may have several advantages over SfM, for instance, theinsensitivity to poor light conditions and modelling errors. This study is setout to answer how point clouds derived from UAV SfM and UAV LiDARcompare to each other regarding detecting potholes of different sizes, wheredetected potholes will be compared to ground truth data. An elevation check,consisting of 126 height control points along the paved road, will also be usedto evaluate the height accuracy in the clouds. Data collection is done with theUAV system mdLiDAR3000DL aaS containing a RIEGL miniVUX-1DLlaser scanner for LiDAR data and Sony RX1R II 42.4 megapixel camera forSfM data. The data for both methods are collected during the same flight. Theproposed method automatically detects and extracts potholes from a pavedsurface based on the vertical distance to local reference planes which representthe undamaged road surface. The point clouds are filtered in CloudComparebefore imported to TerraScan for detection and extraction of potholes. Theextraction results are then controlled by a set of terrestrial measurements bytotal station. The results show that potholes with a smaller width of at least16.5 cm and a depth of at least 2.7 cm can be detected and extracted frompoint clouds derived by UAV LiDAR at a flight altitude of 30 m. Theextracted potholes had a standard deviation of 1.40 cm in width and 6.7 mmin depth. Shadows on the road caused height anomalies in the point cloudproduced by Structure-from-Motion (SfM), which made pothole detectionimpossible with the proposed methodology. / Potthål skapas genom erosion i vägar och uppstår varje år i vägnätet. Skadornapåverkar inte bara fordonens skick, utan kan även vara orsaken till olyckorsom i vissa fall är dödliga. I dagsläget detekteras potthål genom ockulärt frånfordon av kommunala arbetare eller så rapporteras de in av medborgare via etjänst där en lös beskrivning kan ges angående potthålens egenskaper ochposition.På senare tid har studier utforskat möjligheterna för flygburen inspektion avasfalterade vägar med den nya, kostnadseffektiva, Structure-from-Motion(SfM) tekniken som kan producera 3D-punktmoln från fotogrammetrisk data.Punktmolnen som är framtagna genom denna metod har vidare använtstillsammans med bearbetningsalgoritmer för att detektion och extraktion avpotthål i asfalterade vägar. Dock har resultaten inte varit optimala för attmetoden ska fungera i praktiken. Syftet med den här studien är därför attutforska möjligheten för att använda UAV LiDAR som en bättre metod fördenna process. Punktmoln framtagna genom LiDAR-teknik, mer känt somlaserskanning, kan ha ett flertal potentiella fördelar över SfM som okänslighetmot modelleringsfel och dåliga ljusförhållanden.Denna studie ger svar på hur punktmoln framtagna genom UAV LiDAR ochUAV SfM förhåller sig till varandra när det gäller detektion av potthål i olikastorlekar från asfalterade vägar, där potthålens dimensioner kommer attjämföras mot markbundna kontrollmätningar. Vidare görs en höjdkontrollmot 126 höjdstöd i båda punktmolnen för att jämföra kvaliteten förhöjdmätningar på den asfalterade vägen genom respektive metod.Insamlingen av data gjordes samtidigt under samma flygning för bådametoderna. Drönaren som användes var Microdrones mdLiDAR3000DL aaSmed en RIEGL miniVUX-1DL laserskanner och en Sony RX1R II 42,4megapixelkamera monterad. Mjukvarorna som har använts för bearbetning ärCloudCompare för filtrering av brus med mera och TerraScan för självadetektions -och extraktionsprocessen.Resultatet visar att det är möjligt att extrahera potthål från LiDAR-baseradepunktmoln med en mindre bredd på minst 16,5 cm och ett djup på 2,7 cm.Standardavvikelsen för potthålens bredd är 1,4 cm och 6,7 mm i djup.Grupper av avvikande punkter skapades på vägen i det SfM-baseradepunktmolnen som en följd av ett modelleringsfel i skuggområden på vägen,vilket vidare gjorde detektion -och extraktionsprocessen omöjlig med denframtagna metoden.

In-service pavements require maintenance and rehabilitation (MandR) interventions to keep them in compliance with structural and functional standards. With the increased focus on the sustainability of our roadway systems, it has become important to document the cost and environmental impacts of different MandR strategies over the life cycle of the pavement to facilitate project selection decisions in the future. Asphalt pavement recycling, while cost-effective and environmentally friendly compared to other traditional MandR treatments, still faces some widespread implementation push-back, leading to policy enactments by the FHWA aimed at encouraging the use of recycling in road projects. Many agencies and contractors have cited the lack of project selection criteria, and uncertainty about long-term performance of these recycling alternatives as reasons impeding rapid implementation of these treatments in road projects. One of the gray areas of the FHWA's 2015 Recycled Material Policy in project selection was, until recently, the lack of guidelines or tools for the assessment of the environmental suitability of candidate MandR treatments. Today, it is almost impossible to evaluate the environmental suitability of various recycling-based end-of-service-life treatments because available databases do not have relevant information on the details of unit processes, construction equipment and activities, and use-stage roughness data. Development of future MandR plans throughout the service life of pavements rehabilitated with recycling-based treatments is somewhat limited as deterioration is not fully understood. Also, available modeling tools no not address all LCA phases, or in cases where they do, key life cycle phases including the MandR, and use phases are not well covered due to the lack of quantification highlighted earlier. To address the highlighted concerns, this dissertation developed a user-friendly comprehensive LCA tool that was further validated with a case study to quantify the service life (when the pavement has reached a critical threshold performance value) and potential environmental benefits of pavement recycling projects executed by the Virginia Department of Transportation over the past decade. The tool, pySuPave, includes an excel spreadsheet user-inputs interface, and database of economic flows for unit processes used in the production of pavement materials and subsequent construction of the pavement system, considering transportation of materials and construction machinery to plants and construction site. A python-based program was used to perform matrix-based computations to generate the environmental burdens from the available public LCA Ecoinvent database. A substantive part of the dissertation was dedicated to evaluating the performance of in-service pavements rehabilitated with cold recycling and full-depth reclamation treatments, focusing on developing pavement performance prediction models (PPPM) that goes on to improve modelling of the MandR and use stages in the pavement LCA and ultimately bridges the knowledge gap on how these treatments perform in the long term. This part of the dissertation was presented in two chapters; trends in pavement recycling and performance data collection, and development of PPPMs for recycled asphalt pavements. The first provides an update and examines the current state of pavement recycling techniques, highlighting trends in the various recycling methods, examining what is and is not working from the agency perspective, and assessing the progress made in the last decade through a web-based survey. The survey results did not indicate significant changes in the adoption of the asphalt pavement recycling concept in the last decade. However, recycling techniques, such as hot in-place recycling, are being used less and more agencies seem to be adopting lower temperature techniques such as cold in-place recycling, cold central plant recycling and full depth reclamation. Improvements in mix design methods were noticeable, as more agencies have adopted contemporary methods, such as the Superpave design. Among states, very few agencies collected performance data for completed asphalt pavement recycling projects. The second chapter on performance focused on developing individual and family-type PPPMs from the data collected from the states of Virginia and Colorado, respectively. While regression modeling forms the backbone of the approach used, the chapter also presents an approach to developing family-type models using functional data analysis to find groups of projects with similar deterioration trends. In the case of Colorado, cold in-place recycling (CIR) projects completed with an initial IRI between 71 and 91 in/mi are most likely to deteriorate at an average group rate of 1.37 in/mi/year. Similarly, full depth reclamation (FDR) projects will most likely deteriorate following an average group rate of 1.40 in/mi/yr, with an initial IRI between 52 and 70 in/mi. These projects will stay in service well over 30 years if a threshold IRI of 140 in/mi were used a failure criterion. For the individual roughness models developed for VDOT, the initial IRI values and the rate of change for the treatments analyzed were found to range between 48 and 85 in/mi and between 0.70 and 5.20 in/mi/year, respectively, depending on the recycling method and type of stabilization treatment. Finally, a context-based life cycle assessment case study was conducted to benchmark and compare the environmental impacts associated with rehabilitating a low-volume road with various recycled-based and equivalent conventional methods. Several impact indicators were assessed but only the global warming (GW) score and the single score index that combines all the environmental impact indicators into a single number using normalization and weighting factors were reported in this study for the sake of brevity. Four restorative maintenance projects including two CIR (4-in. HMA over a 5-in. CIR with foamed asphalt and emulsion stabilization), one cold central plant recycling (CCPR): 4-in. HMA over a 5-in. foamed asphalt CCPR (CCPR FA), and one non-recycling structural overlay (8-in. HMA over an existing pavement) were evaluated. In addition, the following reconstruction projects were assessed; two FDR (4-in. HMA over a 12-in. FDR with foamed asphalt with 1% cement additive, and a 4-in. HMA over 10.5-in. cement stabilized FDR), and a non-recycling reconstruction project (a new reconstruction project with 8-in. HMA over a 16-in. aggregate base and subbase). The functional unit was a two lane-mile length, 12 feet wide project with a traffic volume of 1000 vehicles (3% trucks) and the analysis was conducted for 50 years. The GW score and a few other impact indicators showed an increase in the observed results where cement is used as a main stabilizer or as an additive. Between the asphalt stabilized projects, the difference in impact scores is only seen when cement is used as an additive as highlighted in the case of foamed asphalt applications. Even for the low-volume road under study, the use stage contributes the largest share to global warming and is—among several factors—attributed to the initial surface roughness of completed projects. Thus, for state DOTs looking to reduce the environmental footprints for road infrastructure projects and achieve federal legislative goals, building smoother roads and taking steps to keep the annual deterioration rate low would be an important measure, in addition to pavement recycling. Comparing the projects based on the overall single score derived from weighting factors from the National Institute of Standards and Technology (NIST) ranks the projects as follows (listed in order decreasing impacts per rehabilitation category); restorative maintenance projects: T. OVERLAY (non-recycling structural overlay—8 in. HMA over an existing pavement) - 1.06 pts, CCPR FA (4 in. HMA over a 5 in. cold central plant recycling with foamed asphalt) - 1.02 pts, CIR FA (4 in. HMA over a 5 in. cold in-place recycling with foamed asphalt) - 1.00 pts, CIR AE (4 in. HMA over a 5 in. cold in-place recycling with emulsion)- 0.86 pts; reconstruction projects: RECONS (a new reconstruction project—8 in. HMA over a 16 in. aggregate base and subbase) -1.42 pts, FDR FA+C (4 in. HMA over a 12 in. FDR with foamed asphalt with 1% cement additive) - 1.15 pts, FDR C (4 in. HMA over 10.5 in. cement stabilized FDR) - 1.02 pts. / Doctor of Philosophy / Due to harsh environmental conditions and continual damage from moving traffic, highway pavements or roadways deteriorate and grow weak over time. Throughout their life in service, different maintenance and rehabilitation (MandR) activities are performed with the intention of slowing down the deterioration to always keep the highway at a certain level of service to road users. For a long time, these MandR activities have included the use of virgin materials in techniques ranging from minor treatment applications such as fog seals, chip seals, thin overlays through more heavy treatments such as mill and fills, thicker overlays all the way to total reconstruction. Other MandR alternatives include pavement recycling which reuses materials from the existing distressed roadways either in-place or at a nearby mobile plant have gained popularity among several state highway agencies over the last decade. The advantages of using the recycling alternatives compared to non-recycling options are many and have been known to include cost savings, less construction time, and low environmental footprint. Many highway agencies, however, have expressed the lack of information on project selection criteria and the uncertainty about long-term performance of these recycling alternatives as reasons impeding rapid and widespread implementation in road projects. Agencies need selection criteria to help them identify the right treatments to apply to the right road at the right time. In a bid to encourage the use of pavement recycling treatments, the Federal Highway Administration (FHWA) enacted the Recycled Materials Policy in 2006 (revised 2015) but the policy did not fully address certain aspects of project selection. Directives on assessing the environmental suitability of recycling projects, for instance, was not given. There are no tools with modern databases incorporating the various unit processes for pavement recycling to aid agencies carry out this environmental assessment. To address the highlighted concerns, we developed a user-friendly comprehensive environmental assessment tool called pySuPave as part of this dissertation. We later validated the tool with a case study to quantify the potential environmental benefits of pavement recycling projects executed by the Virginia Department of Transportation over the past decade. Next, we conducted a survey of the departments of transportation (DOT) around the United States and Canada to collect performance data from agencies with active in-place recycling programs. Approximately 18% of the DOTs surveyed were able to provide performance data. Data received from Colorado and Virginia were subsequently used to developed models to predict deterioration in recycled pavements. In the case of Colorado, CIR projects completed with an initial roughness (IRI) between 71 and 91 in/mi are most likely to deteriorate at a rate of 1.37 in/mi/year. Similarly, FDR projects will most likely deteriorate following an average group rate of 1.40 in/mi/yr, with an initial IRI between 52 and 70 in/mi. These projects will stay in service well over 30 years if a threshold IRI of 140 in/mi were used a failure criterion. For the individual roughness models developed for VDOT, the initial IRI values and the rate of change for the treatments analyzed were found to range between 48 and 85 in/mi and between 0.70 and 5.20 in/mi/year, respectively, depending on the recycling method and type of stabilization treatment Finally, we conducted an environmental assessment case study to benchmark and compare the environmental burdens i.e., global warming (GW) and other impacts associated with rehabilitating a low-volume road with various recycled-based and equivalent non-recycling methods. Four restorative maintenance projects including two CIR (4-in. HMA over a 5-in. CIR with foamed asphalt and emulsion stabilization), one CCPR (4-in. HMA over a 5-in. foamed asphalt CCPR [CCPR FA]), and one non-recycling structural overlay (8-in. HMA over an existing pavement) were evaluate. In addition, the following reconstruction projects were assessed; two FDR (4-in. HMA over a 12-in. FDR with foamed asphalt with 1% cement additive, and a 4-in. HMA over 10.5-in. cement stabilized FDR), and a non-recycling reconstruction project (a new reconstruction project with 8-in. HMA over a 16-in. aggregate base and subbase). The functional unit was a two lane-mile length, 12 feet wide project with a traffic volume of 1000 vehicles (3% trucks) and the analysis was conducted for 50 years. The study results showed that the recycling-based projects had lower overall environmental burdens compared to their equivalent non-recycling alternatives. The GW score and a few other environmental impact indicators were higher when cement is used as a main stabilizer or as an additive in the recycling projects. Between the asphalt stabilized recycling projects, the difference in impact scores is only seen when cement is used as an additive as emphasized in the case of foamed asphalt applications. Even for the low-volume roads under study, the use stage (when the project is open to road-users) in the pavement life cycle contributes the largest share to global warming and is—among several factors—attributed to the initial surface roughness of completed projects. Thus, for state DOTs looking to reduce the environmental footprints for road infrastructure projects and achieve federal legislative goals, building smoother roads and taking steps to keep the annual deterioration rate low would be an important measure, in addition to pavement recycling. The results from this research support the hypothesis that pavement recycling can reduce global warming and other environmental burdens compared to non-recycling methods. Therefore, agencies should encourage more pavement recycling programs.

Induced vibrations due to tire-pavement interaction are one of the main sources of vehicle exterior noise, especially near highways and main roads where traveling speeds are above 50 kph. Its dominant spectral content is approximately within 500-1500 Hz. However, accurate prediction tools within this frequency range are not available. Current methods rely on structural modeling of the complete tire using finite elements and modal expansion approaches that are accurate only at low frequencies. Therefore, alternative physically-based models need to be developed. This work proposes a new approach that incorporates wave behavior along the tire's circumferential direction, while modes are assumed along its transversal direction. The formulation for new infinite plate and cylindrical shell structural models of a tire is presented. These are capable of accounting for orthotropic material properties, different structural parameters between the belt and sidewalls, inflation pressure, and rotation of the tire. In addition, a new contact model between the pavement and the tire is developed presented. The excitation of the tire due to the impact of the tread-pattern blocks in the contact patch region is characterized and coupled to the structure of the tire. Finally, a Boundary Element Method is implemented in order to compute the vibration-induced noise produced by the tire. All the modeling components are combined in a single prediction tool named Wave Pro Tire. Lastly, simulated responses and validation cases are presented in terms of harmonic responses, Frequency Response Functions (FRF), and produced noise. / Doctor of Philosophy / Induced vibrations due to tire-pavement interaction are one of the main sources of vehicle exterior noise, especially near highways and main roads where traveling speeds are above 50 kph. Accurate prediction tools are not currently available. Therefore, new physically based models need to be developed. This work proposes a new approach to model the tire’s structure with a formulation that accounts for multiple physical phenomena. In addition, a model that simulates the contact between the pavement and the tire’s tread is presented. Finally, the vibrations are coupled to the produced noise in a single prediction tool named Wave Pro Tire. This work also includes simulated responses and validation cases.

This thesis investigates the application of In-Situ Recycling and provides guidelines for localities to aid in the selection of recycling methods, as well as documents a local government's experience with Cold In-Place Recycling. The recycling methods discussed in this study include Cold In-Place Recycling (CIR), Hot In-Place Recycling (HIR), and Full Depth Reclamation (FDR). These methods are performed onsite and in-place in a continuous process of milling, mixing, and placement. The In-Situ Recycling guidelines include suggestions based on: traffic characteristics, existing road condition, distress types, road access, local climate, road geometry, and other road characteristics. The guidelines are based on information from sources including NCHRP Synthesis 421, American Recycling and Reclamation Association (ARRA), FHWA, and state agencies with recycling experience. This study also resulted in documenting obstacles that localities may face when in-situ recycling, as well as the impact of limited experience with recycling. The study also evaluated the construction of Cold In-Place Recycled pavement sections in Christiansburg, VA, using Falling Weight Deflectometer (FWD) and Ground Penetrating Radar (GPR). Additionally, using the FWD and GPR data, alternate recycled designs were proposed in addition to a cost comparison to a conventional design. / Master of Science

La baja resistencia y las fallas estructurales tempranas en carreteras asfálticas son problemas comunes en la ingeniería de pavimentos. La causa principal de estos problemas es la deformación constante de las capas que lo componen provocada por el aumento de operación de las cargas del tráfico. La modificación de los ligantes asfálticos es una aplicación empleada desde hace algunos años para mejorar las propiedades del cemento asfaltico y prolongar la vida útil de los pavimentos asfálticos. Los modificadores deben tener características especiales, como en el caso de los elastómeros, que son polímeros con propiedades elásticas y que se pueden manejar a altas temperaturas. En la presente investigación, se analizaron las propiedades básicas del ligante modificado con el elastómero Poliuretano Termoplástico (TPU) en 5, 10 y 15% de adición en peso de asfalto. Asimismo, se empleó el método Marshall para evaluar las propiedades mecánicas y el comportamiento elástico de las mezclas bituminosas modificadas para tránsito liviano, mediano y pesado. Se logró determinar que el punto de inflamación y la recuperación elástica torsional del ligante modificado tuvieron un comportamiento positivo incremental con el aumento de contenido de TPU, mientras que otras propiedades como la solubilidad y la ductilidad no sufrieron variaciones significativas. Por otro lado, la propiedad de penetración disminuía con el contenido del polímero, mejorando su consistencia. Además, se descubrió que las mezclas asfálticas tendrán una mejor capacidad para resistir las deformaciones y un comportamiento mejorado a la fatiga, aunque este último no tan notable. / Low strength and early structural failures in asphalt roads are common problems in pavement engineering. The main cause of these problems is the constant deformation of the layers that compose it caused by the increase in the operation of traffic loads. The modification of asphalt binders is an application that has been used for some years to improve the properties of asphalt cement and extend the useful life of asphalt pavements. Modifiers must have special characteristics, as in the case of elastomers, which are polymers with elastic properties and can be handled at high temperatures. In the present research, the basic properties of the binder modified with the elastomer Thermoplastic Polyurethane (TPU) were analyzed in 5, 10 and 15% addition by weight of asphalt. In addition, the Marshall method was used to evaluate the mechanical properties and elastic behavior of bituminous mixtures modified for light, medium and heavy traffic. It was determined that the flash point and torsional elastic recovery of the modified binder had an incremental positive behavior with the increase in TPU content, while other properties such as solubility and ductility did not undergo significant variations. On the other hand, the penetration property decreased with the content of the polymer, improving its consistency. In addition, it was found that asphalt mixtures will have a better ability to resist deformations and improved fatigue behavior, although the latter is not as noticeable.