Sameh Zaghloul

Project Scoping Using Falling Weight Deflectometer Testing: New Jersey Experience

The experience of New Jersey with pavements, like that of many other states, goes back to the last century. Highways constructed early in this century are still in service. During these extensive service lives, several maintenance and rehabilitation activities were applied to keep the pavements in good condition. These activities ranged from patching to full reconstruction. Also, most of New Jersey pavements have been widened at least once. With all these factors, it is difficult to identify the limits of homogeneous sections that should receive the same rehabilitation treatment. In 1996, the New Jersey Department of Transportation started a limited network level falling weight deflectometer (FWD) program. This program has short- and long-term goals. The short-term goals include identifying the limits of homogeneous sections (sectionalization), assessing the pavement structural capacity, estimating the remaining service life, and determining the future rehabilitation needs. The long-term goal of the project is to use the FWD measurements for the ongoing development and refinement of the models used to predict remaining structural life for use in economic evaluation models. The procedure followed to achieve the short-term goals of the project and an outline of the findings of the project are summarized.

Enhancement of Arizona Pavement Management System for Construction and Maintenance Activities

The Arizona Department of Transportation (ADOT) has used Markovian chain-based pavement management systems (PMS) to support its pavement design, construction, and preservation activities for three decades. These systems provide a strong tool for pavement network optimization. However, the probabilistic nature of the Markovian chain model means that the systems lack the flexibility to consider the distinct conditions associated with individual pavement projects or sections. Recently, a new PMS has been developed and implemented to replace the previous PMS through a research project funded by ADOT. The new system was designed to expand the use of PMS tools to support pavement design, construction, and maintenance operations. Various relevant data, including data on inventory, traffic, pavement structural history, maintenance, and performance, have been integrated into one centralized database to support the systems functions. The system has also incorporated ADOTs overlay design procedure based on the fal...

Validation of Enhanced Integrated Climatic Model Predictions with New Jersey Seasonal Monitoring Data

Environment is one of the essential factors that influence pavement material behavior and consequently its performance. The variation of climatic patterns from region to region, coupled with the variation of site-specific conditions across North America, makes it difficult to develop standard models to account for seasonal variation in material properties that apply for all regions. Consequently, the need to develop regional models becomes an essential requirement for most transportation departments. The enhanced integrated climatic model (EICM) was evaluated to determine its suitability in predicting subsurface temperature and moisture conditions within New Jersey sites. The validation of the model used environmental data collected through pavement instrumentation of a large-scale research study under the sponsorship of the New Jersey Department of Transportation. Site-specific data were input to the model, and the model output parameters were compared against field-measured values. The results of the va...

Full-Car Roughness Index as Summary Roughness Statistic

The international roughness index (IRI) and the half-car roughness index (HRI) are the two commonly used roughness indices for pavement management, decision making, prioritization, budgeting, and planning. This work presents a new statistic, termed the full-car roughness index (FRI), for calculation of roughness from longitudinal pavement profiles. FRI is calculated from a single, equivalent profile that is a composite of four corner profiles based on both civil and mechanical engineering principles. More specifically, the full-car (four-wheel) model combines the rear and front suspension systems through an interdependent relation of motion with the longitudinal axle. To validate this model, the FRI values for different pavement sections are determined for sampling roughness measurements from several states and provinces. Then, the behavior of FRI is compared with that of IRI and HRI. The methodology of assessment uses a Monte Carlo simulation for calibration and validation of the index. Correlations deri...

Investigations of Environmental and Traffic Impacts on Mechanistic-Empirical Pavement Design Guide Predictions

The Mechanistic-Empirical Pavement Design Guide (MEPDG) represents a major improvement on its predecessors, particularly in its comprehensive coverage of environmental impact on pavement performance. Another improvement is the approach introduced to assess and accumulate damage created by traffic. A major strength of the MEPDG is the consideration given to the interaction between environmental, material, and traffic parameters, rather than consideration of only the parameters themselves. The process through which these interactions are considered sounds very comprehensive; however, is it practical? The Enhanced Integrated Climatic Model (EICM) is a core component of the MEPDG; it controls the material properties used in the analysis to a great extent. As a result, EICMpredictionshaveasignificantimpactonMEPDG-accumulateddamage and therefore on predicted service life. In a previous study, an effort was made to validate EICM predictions with field-measured temperature and moisture profiles outside the MEPDG....

Comparative Analysis of Long-Term Field Performance of Recycled Asphalt in California Environmental Zones

A study was performed to evaluate the long-term performance of different pavement materials in California. The performance of many special materials, including recycled asphalt pavement (RAP), was evaluated for actual field performance rather than laboratory-based performance. The sections considered in this study were selected to allow the environmental impact on the performance of a specific treatment to be addressed and comparative analysis between two or more treatments to be performed. This paper focuses on a comparative analysis performed on 47 RAP sections located in three California environmental zones: desert, mountain, and north coast. Comparisons were made between the performance of the RAP sections and those of other treatments located within a reasonable distance on the same route. In total, 131 sections covering seven different treatments were considered. The performance comparisons were made with respect to in situ structural capacity, distress condition, roughness condition, and consistency of construction. Deterioration models were developed and used to estimate the in situ structural capacity, distress condition, and roughness condition for all sections at the same age (5 years) to allow fair comparisons. The expected structural, distress, and roughness service lives were also estimated for all treatments on the basis of the field-observed conditions. The results of the analyses suggested that in all three environmental zones, long-term RAP performance is likely to be comparable to other treatments located within a reasonable distance on the same route.

END-RESULT SPECIFICATIONS FOR WARRANTED ASPHALT PAVEMENTS

Long-term pavement performance is highly dependent on its initial condition. High initial roughness leads to higher maintenance and rehabilitation costs, to shorter service life, and to significant reduction in riding quality. A performance-based specification applicable for new and rehabilitated warranted pavements is developed and presented here. The primary purpose of this specification is control of the initial longitudinal roughness of pavements, which will lead to smoother pavements and hence satisfactory long-term performance. In this specification, pavement roughness is measured by using Class I or calibrated Class II profilometers, such as infrared and laser profilometers. Tests are performed on each asphalt layer before the next layer is constructed. Three criteria are considered in the specification: surface tolerance, roughness indices, and repeated waves. It should be noted that this specification focuses on the functional performance of pavements and does not directly address their structural performances. A user-friendly software is developed to implement this specification. The software is capable of simulating straightedge inspections, calculating roughness statistics, and performing frequency analyses, such as power spectral analysis. With the software, a pavement section can be evaluated, tested, and analyzed in few minutes. Highway agencies as well as contractors will benefit from implementing this specification. Highway agencies will benefit by being able to achieve the goal of having safe, smooth, and economic pavements, and contractors will benefit by reducing maintenance cost during maintenance and warranty periods. Also, contractors will get quick results and meaningful feedback to the paving operation. A payment structure, including bonus payments for extended service lives, is included in the specification. This payment structure is based on the long-term effects of the initial roughness on the pavement life-cycle costs. The bonus program will encourage contractors to achieve higher levels of quality.

Wavelet-Based Multiresolution Analysis of Pavement Profiles as a Diagnostic Tool

Discrete wavelet transform (DWT) was proposed as a new diagnostic tool for locating various frequency-related features of profiles, such as repeated waves and short-lived surface distress, that affect ride quality. The shortcomings of power spectrum density (PSD) analysis in evaluating the distribution of energy of a profile between various frequency bandwidths were pointed out. The theoretical background and the basics of the DWT decomposition algorithm are discussed. Advantages of DWT analysis over PSD analysis in detection of short-lived features of the profile are illustrated by an example. The results of both the PSD and DWT analyses of three profile data, taken from data collected as a part of an ongoing research project sponsored by New Jersey Department of Transportation, are presented. The results indicate that DWT analysis can capture both short-lived high-frequency and long-lived low-frequency features of the profile and, consequently, provides a better representation of the profile characteristics. The application of DWT in the development of new ride indices is also discussed.

PAVEMENT REHABILITATION SELECTION BASED ON MECHANISTIC ANALYSIS AND FIELD DIAGNOSIS OF FALLING WEIGHT DEFLECTOMETER DATA: VIRGINIA EXPERIENCE

The effectiveness of using the field diagnosis and falling weight deflectometer (FWD) mechanistic analysis in reducing a 65-km (40-mi) segment of asphalt pavement to project level segments is discussed, along with selecting a cost-effective rehabilitation strategy. A mechanistic-based analysis was performed on the deflection basins measured from I-85 in Virginia to backcalculate the layer moduli. The 65-km segment was divided into structurally homogeneous sections based on the back-calculated layer moduli. The data of each homogeneous section were analyzed further to assess the in situ structural capacity, to identify weak layers, to estimate the remaining structural life, and to determine the current and future rehabilitation needs. It was found that some sections have almost no remaining structural life, and others have remaining structural life of more than 10 years. A comparison was made between the FWD–field diagnosis rehabilitation program and a visual inspection rehabilitation program. Results of the comparison indicated that the visual inspection rehabilitation program resulted in selecting thicker overlays for some of the project sections (overdesigned) and thinner overlays for the other sections (underdesigned). It is estimated that the difference between the FWD–field diagnosis rehabilitation program and the visual inspection rehabilitation program for the overdesigned sections is in the range of 45 percent of the construction cost (savings). Life-cycle cost analysis (LCCA) was performed to quantify the difference between the two rehabilitation programs for the underdesigned sections. Results of the LCCA indicated that the FWD–field diagnosis rehabilitation program would result in 26 percent and 42 percent reduction in the construction cost and user delay cost, respectively.

Implementation of Reliability-Based Backcalculation Analysis

The reliability concept provides a means of incorporating some degree of certainty into the pavement design process to ensure that the outcomes of the process will provide acceptable levels of service until the end of the intended design life. Pavement structural performance and rehabilitation design are highly dependent on the in situ layer properties. Pavement layer thickness is an essential input in backcalculation analysis performed with measured surface deflections to evaluate the in situ structural capacity of a pavement. Inaccurate thickness information may lead to significant errors in the backcalculated layer moduli and, hence, in the rehabilitation design. Because pavement layer thickness has some degree of variability (normal variability), it is important to consider this variability in the backcalculation analysis and rehabilitation design. A procedure was developed to implement the reliability concept in backcalculation analysis to account for the normal variability in layer thickness within structurally homogeneous sections. This procedure was developed on the basis of in situ layer information obtained from a ground-penetrating radar study performed for the New Jersey Department of Transportation. This paper provides an overview of the procedure, along with the results of the pilot implementation of the procedure. This reliability procedure complements the reliability factor of the 1993 AASHTO pavement design guide, as the latter reliability factor does not account for the in situ layer thickness.