Browsing by Author "McGhee, Kevin K."
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- Best Practices and Performance Assessment for Preventative Maintenance Treatments for Virginia Pavementsde León Izeppi, Edgar; Morrison, Akyiaa; Flintsch, Gerardo W.; McGhee, Kevin K. (Virginia Transportation Research Council, 2015-08)Preventive maintenance has the potential to improve network condition by retarding future pavement deterioration. This report outlines guidelines for implementing a preventive maintenance policy for bituminous pavements. Preventive maintenance treatments currently being used in Virginia include chip seal, slurry seal, microsurfacing, and thin hot mix asphalt overlays. Historical pavement condition data were obtained from the Virginia Department of Transportation’s Pavement Management System for these treatments, and treatment performance models were developed. A district-level treatment selection tool was developed to facilitate the district-level decision-making process. A prioritized list of pavement sections was generated, maximizing the cost-effectiveness of the selected treatments subject to budgetary constraints set by the Central Office. As a pilot implementation, the treatment selection tool was then run for each pavement classification in each district. The results of this pilot suggest that this selection tool has the potential to be a practical decision support tool.
- Comparison of United States Air Force PCI Standard Deviation Values to Default Values to Default Values in ASTM D5340Pullen, Aaron B.; Parsons, Timothy (2015-06-04)This paper presents the results of an analysis of nearly 20 years of Pavement Condition Index (PCI) inspection data from the United States Air Force (USAF), comprised of over 10,000 inspected pavement sections, and compares the standard deviation of the PCI of individual sample units within pavement sections to the published defaults in ASTM D5340 (Standard Test Method for Airport Pavement Condition Index (PCI) Surveys), which is 10 points for asphalt pavements and 15 for Portland cement pavements. The USAF is committed to proactively maintaining and rehabilitating its airfields, in part through performing routine PCI surveys to identify and document distresses present in its airfield pavements. Pavements are divided into sections for inspection based on the pavement design, construction history, and traffic area. Because of the time and effort involved, surveys of entire sections are often beyond available manpower, funding, or time. A statistical sampling routine is defined in ASTM D5340 to reduce the effort required to determine the PCI of a given section of pavement. The sampling rate calculation is based on surveying enough samples to achieve a 95% confidence interval of + or - 5 PCI points and is calculated using the number of sample units and the standard deviation of PCI values of sample units in the section. The standard deviation is not known until after the survey has been accomplished; therefore, default values are provided. This study calculates the standard deviation for each inspected section and compares the results to the defaults. The paper also investigates the effect of other factors such as pavement use, pavement rank, age at time of inspection, and slab size on PCI standard deviation. Results indicate that the default values provided in the standard are generally not conservative for all pavements.
- Continuous Friction Measurement Equipment As a Tool for Improving Crash Rate Prediction: A Pilot Studyde León Izeppi, Edgar; Katicha, Samer W.; Flintsch, Gerardo W.; McCarthy, Ross; McGhee, Kevin K. (Virginia Transportation Research Council, 2016-01)A comprehensive pavement management system includes a Pavement Friction Management Program (PFMP) to ensure pavement surfaces are designed, constructed, and maintained to minimize friction-related crashes in a costeffective manner. The Federal Highway Administration’s (FHWA) Technical Advisory 5040.38 on Pavement Friction Management supersedes a previous advisory that focused on skid crash reduction. In addition to traditional locked-wheel friction-testing devices, this new advisory recommends continuous friction measuring equipment (CFME) as an appropriate method for evaluating pavements. The study described in this report developed a pavement friction inventory for a single construction district in Virginia using the Grip Tester, a low-cost CFME. The continuous friction data were then coupled with crash records to develop a strategy for network analysis that could use friction to improve the ability to predict crash rates. The crash rate analysis applied the well-established methodology suggested by the FHWA for the identification of high crash risk areas using safety performance functions (SPFs), which include empirical Bayes rate estimation from observed crashes. The current Virginia Department of Transportation SPF models were modified to include skid resistance and radius of curvature (interstate and primary system only) to improve the predictive power of the models. A variation of the same methodology was also used to contrast the effect of two different friction repair treatments, i.e., conventional asphalt overlay and high friction surface treatments, to explore how their strategic use can impact network level crash rates. The result suggests significant crash reductions with comprehensive economic savings of $100 million or more when applied to a single relatively rural district. These findings easily justify an aggressive state-level PFMP and further support continued research to quantify the influence of other pavement-related characteristics such as macrotexture, grade, and cross-slope.
- Determination of the In-Place Hot-Mix Asphalt Layer Modulus for Rehabilitation Projects Using a Mechanistic-Empirical ProcedureLoulizi, Amara; Flintsch, Gerardo W.; McGhee, Kevin K. (Virginia Center for Transportation Innovation and Research, 2006-07-01)This project evaluated the procedures proposed by the Mechanistic-Empirical Pavement Design Guide (MEPDG) to characterize existing hot-mix asphalt (HMA) layers for rehabilitation purposes. Thirty-three cores were extracted from nine sites in Virginia to measure their dynamic moduli in the lab. Falling-weight deflectometer (FWD) testing was performed at the sites because the backcalculated moduli are needed for the Level 1 procedure. The resilient modulus was also measured in the lab because it is needed for the Level 2 procedure. A visual pavement rating was performed based on pavement condition because it is needed for the Level 3 procedure. The selected cores were tested for their bulk densities (Gmb) using the AASHTO T166 procedure and then for their dynamic modulus in accordance with the AASHTO TP62-03 standard test method. Then the cores were broken down and tested for their maximum theoretical specific gravity (Gmm) using the AASHTO T-209 procedure. Finally an ignition test was performed to find the percentage of binder and to reclaim the aggregate for gradation analysis. Volumetric properties were then calculated and used as input for the Witczak dynamic modulus prediction equations to find what the MEPDG calls the undamaged master curve of the HMA layer. The FWD data, resilient modulus data, and pavement rating were used to find the damaged master curve of the HMA layer as suggested for input Levels 1, 2, and 3, respectively. It was found that the resilient modulus data needed for a Level 2 type of analysis do not represent the entire HMA layer thickness, and therefore it was recommended that this analysis should not be performed by VDOT when implementing the design guide. The use of Level 1 data is recommended because FWD testing appears to be the only procedure investigated that can measure the overall condition of the entire HMA layer.
- Effect of Air Temperature, Vehicle Speed, and Pavement Surface Aging on Tire/Pavement Noise Measured with On-Board Sound Intensity MethodologyMogrovejo Carrasco, Daniel Estuardo (Virginia Tech, 2013-02-01)The study of the traffic noise as an environmental impact, the search for solutions to this problem, and the development of noise measurement methodologies that help in the search of these solutions, is now a fundamental responsibility for the transportation industry. So, in line with this responsibility, consistent work was made with focus on tire/pavement noise measured over different pavement surfaces, and under different environmental conditions, and different speeds. In a parallel way, work was conducted for the development, improvement, and practical use of the On- Board Sound Intensity (OBSI) methodology for tire/pavement noise measurements. The first part of this thesis shows the results of field experimentation about the influence of external factors like air temperature and vehicle speed over the tire/pavement noise measured with the OBSI methodology. Temperatures from 40 to 90"F were targeted, and speeds from 35 mph to 60 mph (range in which tire/pavement noise becomes predominant for the overall vehicle noise) were tested. For this work a series of seasonal field tests were conducted on a primary road in Virginia over various months. The results were analyzed to quantify the variation of tire/pavement noise with respect to the air temperature and test speed, and therefore to find correction factors for this variables in order to normalize the data taken under different conditions. In the second part of this thesis, the study of tire/pavement noise over different surfaces and measured over a timeframe of three seasons is presented. This part presents results about noise reduction potentials of two proposed "quiet" concrete technologies and 3 proposed "quiet" asphalt surfaces when compared with one another, and with control sections. Also the second part of the thesis includes results about the susceptibility of the proposed surfaces to external factors such as: aging (three seasons involved), air temperature differentials and winter maintenance. In general, the findings show trends that tire/pavement noise slightly decreases as air temperature increases. A gradient of approximately -0.05 dBA/"F was found. It was found as well that tire/pavement noise increases an average of 2.5 dBA for every 10 mph of increased speed. The statistical analysis results for the second part of the thesis shows that all proposed concrete surfaces and asphalt surfaces present benefits in terms of noise reduction, For the asphalt surfaces, it was found that more voids in the surface helps to absorb the noise. In addition, the rubber modified mixes show an improved noise reduction potential. Air temperature normalization was performed an a statistical analysis was conducted; it was found that air temperature has a significant influence in the noise measurements especially for the first months of use. Finally it was found that there is a slightly increase in noise over time after the first months of use.
- Evaluation of Continuous Friction Measuring Equipment (CFME) for Supporting Pavement Friction Management ProgramsNajafi, Shahriar (Virginia Tech, 2010-12-07)It is the responsibility of pavement engineers to design pavements that provide safe and smooth riding surfaces over their entire life cycle. Each year many people around the world lose their lives in vehicle crashes, which are one of the leading causes of death in the United States (US). One of the contributing factors in many of these crashes is inappropriate friction between tires and the pavement. To minimize the impact of this factor, state Departments of Transportation (DOTs) must monitor the friction of their pavement networks systematically and regularly. Several devices are used around the world for measuring friction. Locked-wheel skid trailers are the predominant technology for roadways in the U.S. However, Continues Friction Measuring Equipment (CFME) is emerging as a practical alternative, especially for network-level monitoring. This type of technology has been used for monitoring runway friction for many years and is starting to be used also for measuring roadway friction. This thesis evaluates the different operational characteristics of CFME to provide guidelines for highway agencies interested in using this technology for supporting their friction management programs. It follows a manuscript format and is composed of two papers. The first part of the thesis presents a methodology to objectively synchronize and compare CFME measurements using cross-correlation. This methodology allows for comparing the “shape” of the friction profiles, instead of only the average friction values. The methodology is used for synchronizing friction measurements and assessing the repeatability and reproducibility of the CFME using friction measurements taken on a wide range of surfaces at the Virginia Smart Road. The proposed approach provides highway agencies with a rigorous method to process CFME measurements. The second part of the thesis evaluates the impact of several operational characteristics on the CFME measurements using a field experiment. The results of the experiment confirmed that the measurements are significantly affected by (1) the direction of testing while testing on sections of road with a significant grade, (2) water film thickness, and (3) testing speed. The experiment showed that measurements taken downhill on a 6% grade were significantly higher than those taken uphill. The analysis also verified that, consistent with previous studies, the measured friction decreases with higher water depth and testing speeds. It also showed that the change of friction with speed is approximately linear over the range of speeds used in the experiment. In general, the thesis results suggest that CFME can provide repeatable and reproducible friction profiles that can be used to support friction management programs and other asset management business functions. However, care should be taken with regard to the operational conditions during testing since the measurements are affected by several factors. Further research is needed to (1) quantify the effect of these, and potentially other, operational factors; and (2) establish standard testing condition and approaches for correcting measurements taken under other conditions.
- A Fair Division Approach to Performance-based Cross-Asset Resource AllocationPorras-Alvarado, Juan D.; Han, Zhe; Zhang, Zhanmin (2015-06-04)Resource allocation mechanisms have become a major issue for transportation agencies in the United States and around the world. In order to meet budgetary restrictions resulting from reductions in funding, transportation agencies have explored alternatives to modify the traditional approaches to funding allocation. Most of the alternative methods for funding allocations focus on maximizing infrastructure performance, obviating the consideration of equity. Equity considerations often influence allocation decisions; therefore, the impact of equity should be considered in funding allocation analyses. This paper presents a methodological framework for performance-based cross-asset resource allocation using the fair division method. The fair division method allocates resources in such a way that participants believe they are receiving a fair share based on utility functions. Collective utility functions are used to conduct tradeoff analyses of different allocations in terms of total utility and total envy which are compared to the predicted asset performance. A case study using performance data maintained by the Texas Department of Transportation was conducted to demonstrate the applicability of the proposed framework. Results from the study suggested that the proposed framework for cross-program resource allocation could be an effective and reliable tool for transportation agencies to allocate resources in an objective manner. Additionally, this framework provides the necessary means to incorporate equity factors in the allocation processes, addressing a major shortcoming associated with most traditional approaches to resource allocation.
- Field Investigation of High Performance Pavements in VirginiaFlintsch, Gerardo W.; Al-Qadi, Imad L.; Loulizi, Amara; Lahouar, Samer; McGhee, Kevin K.; Trenton Clark (Virginia Center for Transportation Innovation and Research, 2005-01-01)This study evaluated 18 pavement sections located in high-traffic highways in Virginia to find a premium pavement design with a life span of 40 years or more using current and past field experience. The selected pavement sections were thought to perform well. Eight flexible pavements, six composite pavements, two continuously reinforced concrete pavements, and two jointed plain concrete pavements were investigated. Field testing consisted of (1) falling weight deflectometer (FWD) testing to assess the structural capacity of the different pavements and to backcalculate the pavement layer materials' moduli, (2) ground-penetrating radar (GPR) scanning to determine layer thicknesses and to locate any abnormalities inside the pavements, (3) digital imaging to determine condition indices, (4) longitudinal profile measurements to calculate International Roughness Index, and (5) coring and boring to perform material characterization of pavement layers. Hot mix asphalt tests included resilient modulus and creep compliance. Concrete was tested for compressive strength. The analysis of the collected data suggests that premium pavement designs can be obtained. The field investigations suggest that all the tested sites are performing satisfactorily and show very low structural distress. Limited material-related problems were found at some sites, which induced non-load related distresses. It was also confirmed that FWD, GPR, and digital imaging are very useful tools to assess the condition of existing pavements. Since the three categories of pavements (flexible, composite, and rigid) were found to perform well, the study recommends that evaluation of other pavement sections, which are thought to perform in a less than optimal state, be conducted to define the causes of the less than desired performance. The selection of the most appropriate premium pavement design should be based on a detailed life-cycle cost analysis; hence, such analysis should be performed. Mechanistic empirical modeling of the best performing section within each category would allow the prediction of future pavement performance for use in the life-cycle cost analysis.
- Field Performance of High Friction Surfacesde León Izeppi, Edgar; Flintsch, Gerardo W.; McGhee, Kevin K. (Virginia Center for Transportation Innovation and Research, 2010-06-01)This report describes an evaluation of high friction surface (HFS) systems. The goal of this evaluation was to develop guidance for agencies when considering whether an HFS was an appropriate solution when addressing specific instances of low skid resistance and/or especially high friction demand. HFS systems are specially designed thin surface treatments that provide significant additional skid resistance of pavements and bridge decks without significantly affecting other qualities of the surface such as noise, ride quality, or durability. This report documents the location and climatic conditions where some of these systems are placed, recounts the experiences reported by the agencies that were responsible for their placement, and summarizes key HFS service-level indicators (friction and texture). The agency experiences include a sample benefit-cost analysis from an installation in Wisconsin that justified an HFS application through crash reductions that resulted following the measured increase in skid resistance. Analysis of the service-level indicators included development of the coefficients necessary to obtain the International Friction Index (IFI) values for each of the tested systems. Review of the IFI values suggested that more experiments with different types of wearing surfaces, to include HFS systems as well as more conventional surface treatments, are necessary in order to demonstrate the validity of the speed gradient and friction coefficients recommended by the ASTM standard for the IFI.
- High-speed texture measurement of pavementsMcGhee, Kevin K.; Flintsch, Gerardo W. (Virginia Center for Transportation Innovation and Research, 2003-02-01)This study was conducted to validate high-speed texture measuring equipment for use in highway applications. The evaluation included two high-speed systems and a new static referencing device. Tests were conducted on 22 runway and taxiway test sections from the National Aeronautics and Space Administration's Wallops Flight Facility and 7 surfaces from Virginia's Smart Road. Texture estimates recorded with the high-speed (dynamic) equipment correlated extremely well with estimates made with static referencing methods. The system developed by International Cybernetics Corporation was very functional for most conventional highway surfaces. However, a better correlation may be achieved with the referencing methods by using a system (such as the MGPS surface system developed by the Federal Highway Administration) that produces the American Society for Testing and Materials' standard mean profile depth. Finally, an analysis conducted using the CTMeter (circular track meter, a laser-based but static system) demonstrated an important advantage of combining indices produced from high-definition surface profiles. By comparing the mean profile depth with the root mean square data for a particular surface, it is possible to characterize more fully the shapes that contribute to a pavement's macrotexture.
- Performance Evaluation of Thin Wearing Courses Through Scaled Accelerated TraffickingDruta, Cristian; Wang, Linbing; McGhee, Kevin K. (Virginia. Department of Transportation, 2014-01)The primary objective of this study was to evaluate the permanent deformation (rutting) and fatigue performance of several thin asphalt concrete wearing courses using a scaled-down accelerated pavement testing device. The accelerated testing was conducted using a model mobile load simulator (MMLS3). Field testing with the MMLS3 was conducted on a 4.75-mm nominal maximum aggregate size dense-graded mixture installed at the Turner-Fairbank Highway Research Center. This mixture (designated SM-4.75), two other conventional dense-graded mixtures, and a thin gap-graded mixture were also used to prepare specimens for laboratory rutting tests using the MMLS3. Test results from more than 100,000 wheel load applications of the MMLS3 showed that the thin wearing courses underwent various degrees of permanent deformation depending on their compacted air void content. According to the protocol guidelines developed for the evaluation of permanent deformation and moisture damage when using the MMLS3, most of the mixtures performed well. One exception was a coarser dense-graded material with a high amount of recycled asphalt pavement. No indication of fatigue cracking or other distress was observed for any mixture during or after testing. The study supports use of the SM-4.75 mixture on low- to medium-traffic roadways and for maintenance and/or preservation applications. It further recommends that the Virginia Department of Transportation apply the methods demonstrated through this research to assess better the stability of experimental wearing course mixtures in advance of wider spread field applications.
- Performing Network Level Crash Evaluation Using Skid ResistanceMcCarthy, Ross James (Virginia Tech, 2015-09-09)Evaluation of crash count data as a function of roadway characteristics allows Departments of Transportation to predict expected average crash risks in order to assist in identifying segments that could benefit from various treatments. Currently, the evaluation is performed using negative binomial regression, as a function of average annual daily traffic (AADT) and other variables. For this thesis, a crash study was carried out for the interstate, primary and secondary routes, in the Salem District of Virginia. The data used in the study included the following information obtained from Virginia Department of Transportation (VDOT) records: 2010 to 2012 crash data, 2010 to 2012 AADT, and horizontal radius of curvature (CV). Additionally, tire-pavement friction or skid resistance was measured using a continuous friction measurement, fixed-slip device called a Grip Tester. In keeping with the current practice, negative binomial regression was used to relate the crash data to the AADT, skid resistance and CV. To determine which of the variables to include in the final models, the Akaike Information Criterion (AIC) and Log-Likelihood Ratio Tests were performed. By mathematically combining the information acquired from the negative binomial regression models and the information contained in the crash counts, the parameters of each network's true average crash risks were empirically estimated using the Empirical Bayes (EB) approach. The new estimated average crash risks were then used to rank segments according to their empirically estimated crash risk and to prioritize segments according to their expected crash reduction if a friction treatment were applied.
- Quantifying the Relationship Between Skid Resistance and Wet Weather Accidents for Virginia DataKuttesch, Jeffrey S. (Virginia Tech, 2004-09-13)One of the factors contributing to motor vehicle crashes is lack of sufficient friction at the tire-pavement interface. Although the relationship between surface friction and roadway safety has long been recognized, attempts to quantify the effect of pavement skid resistance on wet accident rates have produced inconsistent results. This thesis analyzes the relationships between skid resistance, accident, and traffic data for the state of Virginia. The correlation between wet skid resistance measured with a locked-wheel trailer using a smooth tire and wet accident rates is examined. Additionally, the influence of traffic volumes on accident rates is considered. The research used accident and skid data from the Virginia wet accident reduction program as well as from sections without pre-identified accident or skid problems. The wet accident data was aggregated in 1.6 km (1 mi) sections and divided by the annual traffic to obtain wet accident rates. The minimum skid number measured on each of these sections was then obtained and added to the database. Regression analyses indicated that there is statistically significant effect of skid resistance on wet accident rate; the wet accident rate increases with decreasing skid numbers. However, as expected, skid resistance alone does a poor job of modeling the variability in the wet accident rates. In addition, the wet accident rate also decreases with increasing traffic volume. Based on the data studied, a target skid number (SN(64)S) of 25 to 30 appears to be justified.
- Recovering from the 2010 Nashville Flood: Pavement Management as a Tool in Long Term Disaster RecoveryReid, Donald; Walter, Jacob (2015-06-04)In the spring of 2010, Nashville, Tennessee and surrounding Davidson County (commonly referred to as "Metro") was hit by a massive flood along the Cumberland River and its associated tributaries. This event broke nearly all flood-related records for the Nashville area and was identified as a 1,000-year flood by the National Weather Service. Damage to the transportation network was significant; flood related damages to pavement included major surface damage, washouts, and erosion of the soil that Metro's roads are built upon. This paper is a case study of Metro's response to the 2010 flood with respect to its roadway network and the role the existing pavement management system played in the long-term recovery of Metro's pavements. It discusses the impacts of the flooding, how the system was used to identify repair areas, how the appropriate approach was determined for specific damaged areas, and how the results of repairs were tracked to ensure that they were both appropriate and effective. The development of new approaches used to address an event of this magnitude along with the impact to Metro's financial reporting and ability to issue bonds will also be discussed.
- Road Network Pavement Management ProgramMcCarthy, Ross; de León Izeppi, Edgar; Flintsch, Gerardo W.; McGhee, Kevin K. (2014-09-01)
- Splash and Spray Assessment Tool Development Program: Final ReportFlintsch, Gerardo W.; Tang, Lijie; Katicha, Samer W.; de León Izeppi, Edgar; Viner, Helen; Dunford, Alan; Nesnas, Kamal; Coyle, Fiona; Sanders, Peter; Gibbons, Ronald B.; Williams, Brian M.; Hargreaves, David; Parry, Tony; McGhee, Kevin K.; Larson, Roger M.; Smith, Kelly L. (Virginia Tech. Virginia Tech Transportation Institute, 2014-10-07)The effects of vehicle splash and spray are well known to motorists who have driven in wet weather conditions. Research suggests that splash and spray contribute to a small but measurable portion of road traffic accidents and are the source of considerable nuisance to motorists. Splash and spray from highway pavements also can carry a number of pollutants and contaminants. When deposited, these contaminants can be poisonous to plant life and accelerate the corrosion of roadway appurtenances. Splash and spray are individually definable processes that are the product of a number of different factors. Many parties have gone to great lengths to reduce the splash and spray created by motor vehicles, especially that from heavy vehicles, by retrofitting devices that alter the vehicle’s aerodynamics. Another possible solution to the problem is to change the characteristics of the highway pavement. Previous research shows that pavement geometry, drainage, texture, and porosity all contribute to splash and spray generation, but the exact mechanisms are largely unknown. A model capable of predicting the splash and spray propensity of pavements can be used by highway engineers to support decisions in highway maintenance and design. The project objective was to develop a simple and practical assessment tool to characterize the propensity of highway sections to generate splash and spray during rainfall and the impact of splash and spray on road users. This report summarizes the development of the splash and spray model and its implementation in an easy-to-use, practical tool.
- Use of a Digital Survey Vehicle for Pavement Condition Surveys at AirportsWilke, Paul W. (2015-06-04)Pavement Management Systems (PMS's) are used extensively as a tool to manage airfield pavements. The pavement surface condition survey is a primary component of all PMS's. Traditionally, pavement condition surveys at airports have been conducted using a foot-on-ground (FOG) approach where inspectors walk the pavement area and collect detailed distress data. In contrast, most highway pavement condition surveys are conducted by driving over the paved area; many of these driving surveys are now completed using a digital survey vehicle (DSV). The DSV collects downward facing pavement video, photographs, and other data while traveling at speeds up to 60 miles per hour (100 kilometers per hour). The DSV offers several advantages over the FOG approach. One of the main advantages for airports is the speed of field data collection which minimizes the disruption to airfield operations. Some have been reluctant to use the DSV for airport condition surveys because of real or perceived limitations of the DSV approach. Airport pavements, especially runways, are significantly wider than roadway lanes thus requiring multiple passes of a DSV to collect data over the full pavement width which can pose challenges in referencing the relative position of each run. Other concerns include detection of pavement defects that pose a risk of foreign object damage (FOD) to aircraft and detection of slight rutting that may not be visible from DSV images. This paper describes the advantages and disadvantages of DSV and FOG approaches to airport condition surveys as well as special considerations for mitigation of potential problems while using the DSV approach.
- Use of Emerging Technologies in support of Pavement Preservation Decision MakingRada, Gonzalo R.; Visintine, Beth A.; Hicks, R. Gary; Cheng, DingXin; Van, Thomas P. (2015-06-04)Pavement preservation represents a proactive approach to maintaining and extending the lives of existing highways. Not surprisingly, pavement performance is at the heart of the preservation decision-making process. Traditionally, non-structural factors, such as distress and ride quality, have been used as the primary indicators for pavement preservation strategy selection and timing. However, these factors do not address structural condition, which is of great significance since the concept of preservation is predicated upon applying treatments to structurally sound pavements. Accordingly, the Federal Highway Administration (FHWA) undertook a study to identify emerging technologies to better characterize pavement conditions, predict future deterioration and demonstrate their applicability in the selection and timing of preservation strategies. As part of this study, a literature review and expert interviews were conducted to build a foundation for identifying and evaluating technologies. The evaluation process resulted in four technologies being recommended based on their potential application for pavement evaluation and forecasting. Case study reviews of these technologies were prepared, which highlighted the benefits provided by implementation of the technologies by agencies as well as some of the challenges faced during implementation. This paper focuses on the use of the recommended technologies within the pavement preservation operations of highway agencies. To accomplish this, relevant information extracted from the case study reviews as well as implementation considerations developed during the study are presented in the paper.
- Using high-speed texture measurements to improve the uniformity of hot-mix asphaltMcGhee, Kevin K.; Flintsch, Gerardo W.; de León Izeppi, Edgar (Virginia Center for Transportation Innovation and Research, 2003-05-01)This study introduces Virginia's efforts to apply high-speed texture measurement as a tool to improve the uniformity of hot-mix asphalt (HMA) pavements. Three approaches for detecting and quantifying HMA segregation through measuring pavement surface macrotexture were evaluated: (1) applying the methods proposed in NCHRP Report 441, which build on the ability to predict the expected "non-segregated" macrotexture; (2) using acceptance bands for texture similar to those used for HMA density; and (3) considering the standard deviation of the macrotexture as a measure of construction uniformity. Based on the findings from a series of field tests, the researchers concluded that macrotexture measurement holds great promise as a tool to detect and quantify segregation for quality assurance purposes. None of the available equations for predicting non-segregated macrotexture (the approach in NCHRP Report 441) was found to work for all the construction projects evaluated. Additional information is necessary to establish target macrotexture levels. The acceptance bands approach produced reasonable results in most of the field-verification experiments, but it was significantly influenced by the actual variability within the section. An approach that used target levels of standard deviations was selected for further testing and implementation on a pilot basis.