Nadarajah Sivaneswaran

Mechanistic-Empirical and Life-Cycle Cost Analysis for Optimizing Flexible Pavement Maintenance and Rehabilitation

In this study, an attempt was made to evaluate and select an optimal Maintenance and Rehabilitation (MR Maintenance; Rehabilitation; Life cycles; Costs. Author keywords: Mechanistic; Empirical; Perpetual; Pavement; Maintenance & rehabilitation; Preservation; Life cycle cost.

Efficient Simulation Techniques for Reliability Analysis of Flexible Pavements Using the Mechanistic-Empirical Pavement Design Guide

Many sources of uncertainty are inherent in pavement design. These uncertainties must be incorporated systematically in a reliability analysis to compute their combined effects on the probability of failure of a given pavement structure. Monte Carlo simulation has been the technique of choice in the past to simulate the effects of uncertainties in input parameters on pavement distress and the resultant reliability analyses. The impractical computational time associated with a Monte Carlo scheme, however, has prompted the deferral of the implementation of similar techniques in the current Mechanistic-Empirical Pavement Design Guide (MEPDG). Instead, the reliability analysis implemented in the current MEPDG is performed on the basis of a simple assessment of the overall standard error of the predicted distress compared to the observed distress of the long-term pavement performance (LTPP) sections. It relies on a set of predetermined variability values obtained from a performance database instead of the site...

Robust Deflection Indices from Traffic-Speed Deflectometer Measurements to Predict Critical Pavement Responses for Network-Level Pavement Management System Application

AbstractTraffic-speed deflectometers (TSD) are used in several countries to evaluate the pavement structural condition at the network level. Fatigue and rutting strains are commonly used as pavement critical responses in mechanistic-empirical design procedures to predict pavement structural performance. For successful pavement management system (PMS) application, robust indices that can be readily computed from TSD measurements and best related to the pavement critical responses should be identified. In this study, a comprehensive sensitivity analysis on deflection basin indices and their correlations with fatigue and rutting strains is performed using a range of pavement structures. A commercially available program was used in the first part of the study to compute dynamic deflection basins and evaluate the effects of material properties and vehicle speed on the indices. The indices that best relate to critical responses were identified from the software analyses and subsequently evaluated with a wider r...

Impact of Pavement Monitoring Frequency on Pavement Management System Decisions

Pavement performance monitoring is an essential part of a pavement management system (PMS). Therefore, highway agencies collect pavement condition data containing various structural and functional distresses on a regular basis. How frequently pavement condition data are collected varies. The effect of pavement monitoring frequency on pavement performance prediction and its consequence at network-level PMS decisions were explored. A statistical methodology was developed to investigate the impact of monitoring frequency on performance prediction with different model forms. The results of the analyses showed that performance predictions were affected by monitoring interval. Furthermore, the various types of distress to be collected might need different monitoring intervals because of their unique growth over time and associated uncertainty in prediction. When cost consequences and prediction uncertainties were combined, monitoring of cracking (image based) at 1-year intervals appeared to be more appropriate, whereas for roughness (sensor based), a monitoring interval of 1 to 2 years appeared to be suitable. The results of network-level analyses demonstrated that monitoring interval might significantly affect the short- and long-term network conditions for various preservation strategies. Increasing the monitoring interval may have consequences for PMS decisions. Longer intervals for crack monitoring (image based) might cause an overestimation of agency costs for pavement repair at the network level. Longer intervals for international roughness index monitoring (sensor based) will result in an underestimation of repair costs at the network level.

Geographic Information System-Based Regional Transit Feasibility Analysis and Simulation Tool

A regional transit feasibility analysis and simulation tool (called RTFAST) can be used to analyze and simulate regional transit system performance. The growth of urban areas coupled with changes in socioeconomic and demographic patterns has resulted in the need to provide for mobility and accessibility in regional and multijurisdictional contexts. In this context, the ability to analyze, simulate, identify, and plan regional transit systems to best serve personal travel patterns is necessary. RTFAST has been developed within a geographic information system–based environment and effectively interfaced with existing travel-demand modeling systems. The capabilities of the tool were demonstrated, and sample results were obtained from its application in Florida.

ENGINEERING APPLICATION OF WASHINGTON STATE'S PAVEMENT MANAGEMENT SYSTEM

Previous investigation into the Washington State Department of Transportation’s (WSDOT) Pavement Management System (WSPMS) revealed pavement sections on the state route system that were outperforming or underperforming other pavement sections constructed of similar materials and subjected to similar traffic and environmental conditions. Reasons were not clear. The WSPMS was used to identify superior and inferior candidate pavements for further investigation. All state route pavements were stratified into 18 distinct analysis groups, and population statistics were generated for each group providing WSDOT with a snapshot of the current “state of the state route system” and providing the basis for selecting candidate pavements. The five performance measures considered included: age of the surface course, a distress-based pavement structural condition score, annual design-lane equivalent single axle loads, roughness (in terms of International Roughness Index), and rutting. Results of the analysis suggest that WSDOT is properly designing layer thicknesses at appropriate reliability levels. Also, in 6 of 10 analysis group comparisons, inferior pavements were actually thicker than superior pavements. Both findings suggest that thickness design factors are not the primary cause of inferior performance in Washington State; construction, material and site specific factors are likely the cause. Additionally, in an international effort to exchange information on pavement performance and construction practices, highlights of a comparative study of pavement performance with South Africa’s Gauteng Department of Transportation are presented.

Incorporating Traffic Speed Deflection Devices in Structural Evaluation of Flexible Pavement: Methodologies for Pavement Management Application

Pavement management systems of highway agencies in the various states are primarily based on surface condition data. Surface cracking is used as the main indicator of pavement structural condition. However, with effective pavement treatment that intervenes early to preserve and extend the life of pavements and increasingly thicker long-life pavements, surface cracks no longer tell the true structural condition, or health, of the pavement structure. In addition, surface cracks lack an indicator of pavement deterioration. Knowledge of the true pavement structural condition and the rate of deterioration is needed not only for planning of optimal structural rehabilitation activities and future budget needs but also for implementing a performance-based federal-aid program. This paper presents a methodology for interpreting measurements from traffic speed deflection devices (TSDDs) to track flexible pavement structural condition over time and for assessing rehabilitation needs at a network level to address both structural adequacy and surface condition. The paper also demonstrates a methodology for interpreting TSDD measurements to estimate remaining pavement structural capacity. Curvature indexes measured from TSDD were found to be reasonable estimators of pavement structural condition and were used in the demonstration. Horizontal tensile strain, a primary initiator of fatigue damage and cracking, can be estimated from periodic TSDD measurements and used as a leading indicator of pavement deterioration and structural performance. Any differences in pavement structural performance arising from the pavements as-designed versus as-constructed state and its assumed versus actual traffic and climate effects can be assessed and future treatments modified as necessary.

Probabilistic Life-Cycle Assessment as Network-Level Evaluation Tool for Use and Maintenance Phases of Pavements

Agencies that manage pavement networks have a role in mitigating the factors affecting global climate change by managing their networks in such a way that these factors are minimized. Although much research is still required to quantify the climate change impact of many variables relating to pavements, the impact of pavement condition on vehicle fuel consumption has been clearly demonstrated in several research projects. In the light of extensive research that shows pavement characteristics as having a significant impact on vehicle fuel consumption, it can be shown that maintaining a network of pavements to minimize roughness can limit the energy consumption of vehicles traveling along the pavement network. The objective of this study was to demonstrate a method by which transportation agencies could measure the impact of their management decisions on reducing the energy consumption of their networks. The use of a life-cycle assessment (LCA) to quantify energy consumption probabilistically for a given set of expected maintenance actions defined at the network level is demonstrated. This study shows how the results of the LCA can be used to evaluate the energy consumption attributed to the pavement network over a defined time frame.

Part 3: Managing and Evaluating Pavement Efforts: The Highway Development and Management System in Washington State: Calibration and Application for the Department of Transportation Road Network

The Highway Development and Management System (HDM-4) developed by the World Bank is a powerful pavement management software tool capable of performing technical and economic appraisals of road projects, investigating road investment programs, and analyzing road network preservation strategies. Its effectiveness is dependent on the proper calibration of its predictive models to local conditions. Although significant work has been done in calibrating and applying HDM-4 worldwide (especially in developing nations), no substantial effort has been made within the United States. This paper describes the calibration and application of HDM-4 (Version 1.3) to the Washington State Department of Transportations (WSDOT) road network. WSDOT hopes to use HDM-4 to supplement its existing Washington State Pavement Management System (WSPMS) in long-term pavement performance and financial needs. Significant findings are that (a) HDM-4 can be used to analyze the WSDOT road network, (b) HDM-4 was successfully calibrated fo...

Washington State's Web-Enabled Pavement-Management System

WebWSPMS is an Internet application that allows Washington State Pavement Management System (WSPMS) data to be accessed and analyzed via the World Wide Web. With WebWSPMS, data can be searched, browsed, and accessed either textually or spatially and displayed in a web format. Data available to users include, but are not limited to, roadway geometric data, pavement surveys, performance projections, historical project data, traffic data, and a complete set of digital images for the entire Washington State Department of Transportation (WSDOT) road network. Access is readily available to all authorized users and requires only a computer, a web browser, and an Internet or intranet (for WSDOT personnel) connection. The increased access and analysis capabilities offered by WebWSPMS allow much greater and easier use of the system by both experts and novices alike, which has the potential to increase efficiency and produce more varied and novel approaches to data analysis. Overall, this effort improves WSDOTs ability to develop knowledge, relationships, and models to facilitate improved pavement planning, design, construction, rehabilitation, and performance predictions for Washington State pavements. The envisioned complete WebWSPMS product is described, with examples provided from the current development effort, which is available online at http://hotmix.ce.washington.edu/wspms.