Gerardo W Flintsch

Pavement Surface Macrotexture Measurement and Applications

Different techniques for measuring pavement surface macrotexture and their application in pavement management are discussed. The main applications of surface macrotexture are to measure the frictional properties of the pavement surface and to detect hot-mix asphalt (HMA) construction segregation or nonuniformity. Since surface macro-texture can be measured quite efficiently using noncontact technologies and provides important information regarding pavement safety and HMA construction quality, this parameter may be included in the quality assurance or control procedures. Correlations between different measuring devices were investigated utilizing different HMA wearing surfaces. Excellent correlation was found between the circular track meter and sand patch measurements. In addition, the macrotexture determined using a laser profiler correlates well with that determined with sand patch measurements. Consistent with previous studies, it was found that the skid number gradient with speed is inversely proportional to the pavement macrotexture. However, there was a noticeable difference in speed dependency when smooth and ribbed tires were used. Oscillations in the percent normalized gradient with time due to seasonal variations were also observed. Macrotexture measurements hold great promise as tools to detect and quantify segregation for quality assurance purposes. A standard construction specification was proposed in a recent NCHRP study. However, the equation proposed for computing the nonsegregated estimated (mean) texture depth could not be applied to the mixes studied. An alternative equation has been proposed, which estimates the surface macrotexture using the mix nominal maximum size and voids in the mineral aggregate. The study was based on the mixes used at the Virginia Smart Road. Further investigation using other mixes is recommended.

Pavement Preservation Optimization Considering Multiple Objectives and Budget Variability

Pavement preservation programming often involves multiple objective considerations. Traditional single-objective optimization frameworks consider one single objective while imposing competing objectives as constraints in the optimization formulation. This paper proposes an approach for pavement preservation programming that uses multiobjective optimization and chance constraints. This approach can handle multiple incommensurable and conflicting objectives while considering probabilistic constraints related to the available budget over the planning horizon. The implementation of the approach in a case study with two conflicting objectives of: (1) maximizing the network level of service in terms of weighted average state condition; and (2) minimizing the total preservation cost, shows that its application provides a practical and flexible tool to determine optimal allocation of resources for pavement preservation that reflects agency goals, resource limitations, and performance targets.

Selection of pavement performance models for use in the Portuguese PMS

This paper compares different pavement performance models (PPMs) from around the world and recommends one for use in the Portuguese pavement management systems (PMS). The paper is divided into three complementary sections. The first section describes several PPMs used around the world. The models analysed are (or come from) the Highway Development and Management System, the American Association of State Highway and Transportation Officials, the Nevada PMS, the Collop–Cebon whole-life pavement performance, the Swedish PMS and the Spanish PMS. The second section compares the results obtained for a case study with those of the two most promising PPMs and presents the advantages and disadvantages of using these models. The models were tested using the strategies evaluation tool, one of the components of the PMS utilised by the main Portuguese concessionaire. The final section of the paper presents the conclusions of the study on the use of the PPM evaluated and recommends one model to be used for managing the Portuguese highway network.

Quality Management of Pavement Condition Data Collection

Transportation agencies are developing procedures and guidelines for managing the quality of pavement data collected to ensure the data meet the needs of the pavement management process. This study reviews the quality management practices being employed by public highway agencies for automated, semi-automated, and manual pavement data collection and delivery. Information was gathered through literature review, surveys of U.S. state and Canadian province public agencies and private contractors, and selected interviews.

Multi-attribute life cycle assessment of preventive maintenance treatments on road pavements for achieving environmental sustainability

PurposeAlthough a significant number of environmental protection measures concerning industrial products and processes have emerged over the past few years, similar measures have only started to appear in road construction and related practices. There is a need for understanding what a “sustainable pavement” would entail in terms of greenhouse gas emissions and energy consumption. Since environmental impact assessment of major projects is becoming mandatory in many countries, various research projects attempt to evaluate the environmental impact of different pavement materials, technologies, or processes over the road life cycle. To support these efforts, there is a need to measure and describe different aspects of sustainability related to road pavements. In particular, keeping road pavements at high service levels through a preventive maintenance approach during the pavement service life has been proven to provide significant improvement of their performance and reduce their deterioration rate.MethodologyThis paper describes an innovative methodology to evaluate the environmental impact of preventive maintenance activities. It relates these activities to performance and cost during the service life of the pavement through a multi-attribute “life cycle cost, performance, and environmental analysis”. Emissions and energy saved adopting several preventive maintenance strategies were computed, relating them to cost and performance. Equipment and materials usually involved in road maintenance practices were also analyzed in order to assess specific fuel consumption and energy spent. An ad hoc index was ultimately created, adopting a script file to evaluate the best strategy through the multi-attribute approach.Results and conclusionsResults show how eco-effective it can be to improve pavement management practices on roads by implementing energy efficient treatments and strategies. Furthermore, eco-saving factors could represent a new and innovative feature to be added in the sustainability assessment process for pavements to evaluate different alternatives and assist authorities choosing between different investment solutions as a part of a decision support system.

A life cycle assessment model for pavement management: methodology and computational framework

Despite the general consensus among stakeholders on how useful the life cycle assessment (LCA) methodology can be in helping to reduce the environmental burdens of a road pavement, very few pavement LCA models have considered the entire pavement life cycle. This paper presents the development of a highly customisable LCA tool that provides an integrated, project-level approach that includes all six pavement life cycle phases. The developed tool encompasses six main modules, including extraction of raw materials and production; construction, maintenance and rehabilitation; transportation of materials; work-zone traffic management; usage; and end-of-life. Data regarding the Portuguese practise of pavement construction and management have been collected on site with certified Portuguese construction companies and complemented using published literature and databases. The research described in this paper provides a widely applicable pavement LCA model that will enable highway agencies, private companies and the construction industry to estimate emissions and environmental impacts during the project analysis period for road pavement. The use of the proposed tool for benchmarking current practises in pavement construction and management enhances the scientific basis for understanding where further efforts can be undertaken to promote sustainable pavement investment decisions.

Comparing Resilient Modulus and Dynamic Modulus of Hot-Mix Asphalt as Material Properties for Flexible Pavement Design

With the current trend toward developing mechanistic flexible pavement design and the need for more reliable design procedures, accurate characterization of hot-mix asphalt (HMA) properties is needed. Resilient and dynamic modulus tests were performed at five temperatures on two typical mixes used in the Commonwealth of Virginia to compare the test results. The dynamic modulus was measured at six frequencies at each of the testing temperatures, and the resilient modulus test was performed at one loading time. The study found that the size of the specimen statistically affected the measured resilient modulus value. Resilient modulus values obtained in the 100-mm-diameter specimens were higher than those obtained in the 150-mm-diameter specimens at all testing temperatures. No statistical differences were observed in the resilient modulus of the two mixes. However, statistical differences were found in the dynamic modulus of the two mixes. A strong relation between the dynamic modulus test performed at 5 Hz...

A life cycle assessment of in-place recycling and conventional pavement construction and maintenance practices

The application of in-place recycling techniques has emerged as a practical and effective way to enhance the sustainability of agency pavement management decisions for asphalt-surfaced pavements. However, the potential environmental benefits resulting from applying in-place recycling techniques have not been fully documented in the literature. This paper presents a comprehensive pavement life cycle assessment (LCA) model that extends the typical pavement LCAs system boundaries to include the environmental impacts resulting from the usage phase and the production of the energy sources. The results of the application of the pavement LCA model to a specific highway rehabilitation project in the state of Virginia showed that in-place recycling practices and an effective control of the pavement roughness can improve significantly the life cycle environmental performance of a pavement system.

Examining Effects of Climatic Factors on Flexible Pavement Performance and Service Life

The potential risk of climate change raises interest in how it may affect the deterioration rates of flexible pavements and how pavement service lives would be altered as a consequence. Previous studies demonstrated that temperature is the most influential environmental factor for the Mechanistic–Empirical Pavement Design Guide. In this study, temperature factors, both the increase in average annual temperature and the seasonal variation in temperature, are examined through a sensitivity analysis. The sensitivity of the pavement performance to temperature as well as other environmental factors such as precipitation, wind speed, percent sunshine, and groundwater level is included as a comparison. This study concluded that temperature factors, both the increase in average annual temperature and the seasonal variation, are the most influential in pavement performance. Moreover, pavement service life may experience considerable reduction because of climate change in some regions if design is not adapted to the changed climate.

Stereo-vision applications to reconstruct the 3D texture of pavement surface

Characterisation of pavement surface texture has significant effects on ride comfort and road safety. Pavement texture is typically reported as a single attribute, such as mean profile depth, root mean square roughness or hydraulic radius, which limits the usefulness of information extracted from texture measurements. Therefore, advanced methods that characterise pavement texture in three dimensions are needed. This paper reviews recent advances in the development of two imaging-based texture evaluation methods. The main objective of these methods is to recover the 3D heights of the pavement surface. Also, the validation of the proposed image-based texture indicators is examined. Results show that image-based techniques can be successfully applied to recover the 3D heights of pavement surface textures and provide substantial information on the friction and noise characteristics of the surface.