abstract: Pavement preservation is the practice of selecting and applying maintenance activities in order to extend pavement life, enhance performance, and ensure cost effectiveness. Pavement preservation methods should be applied before pavements display significant amounts of environmental distress. The long-term effectiveness of different pavement preservation techniques can be measured in terms of life extension, relative benefit, and benefit-cost ratio. Optimal timing of pavement preservation means that the given maintenance treatment is applied so that it will extend the life of the roadway for the longest possible period with the minimum cost. This document examines the effectiveness of chip seal treatment in four climatic zones in the United States. The Long-Term Pavement Performance database was used to extract roughness and traffic data, as well as the maintenance and rehabilitation histories of treated and untreated sections. The sections were categorized into smooth, medium, and rough pavements, based upon initial condition as indicated by the International Roughness Index. Pavement performance of treated and untreated sections was collectively modeled using exponential regression analysis. Effectiveness was evaluated in terms of life extension, relative benefit, and benefit-cost ratio. The results of the study verified the assumption that treated sections performed better than untreated sections. The results also showed that the life extension, relative benefit, and benefit cost ratio are highest for sections whose initial condition is smooth at the time of chip seal treatment. These same measures of effectiveness are lowest for pavements whose condition is rough at the time of treatment. Chip seal treatment effectiveness showed no correlation to climatic conditions or to traffic levels. / Dissertation/Thesis / M.S. Civil Engineering 2012

Preventive maintenance has the potential to improve network condition by retarding future pavement deterioration. The Virginia Department of Transportation uses its pavement management system to determine maintenance targets for each district. The districts then use these recommendations to select pavements that will receive maintenance and the types of treatments that will be applied. Each district has a different approach to preventive maintenance. There was a need for more consistent preventive maintenance practices across the state. This thesis outlines guidelines for the implementation of a preventive maintenance policy. Preventive maintenance treatments currently being used within Virginia include chip seal, slurry seal, microsurfacing, and thin hot mix asphalt overlays. Historical pavement condition data was obtained from the VDOT PMS for these treatments and treatment performance models were developed. A district level treatment selection tool was developed to assist 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. The treatment selection tool was then run for each pavement classification in each district. The results of this analysis were presented. Although the recommended budget for each district was very close to the targets set by the central office, the recommended lane miles for each district were about half the targets set by the central office.  It is believed that the unit costs used in this analysis were higher than those used in the VDOT PMS analysis. This selection tool has the potential to be a very powerful decision support tool if the unit costs are representative of what the expected treatment costs are for each district. / Master of Science

Pavement management is one of the primary responsibilities for departments of transportation and other municipalities across the country. Efficient and proper use of taxpayer dollars to preserve and improve the existing transportation system has never been more important due to the current fiscal environment. Agencies use pavement management systems to store data describing the state of the network. This information is often used to help make decisions regarding the location of pavement preservation actions. There is often a discrepancy between the need estimates of network-level pavement management systems and where and how pavement preservation and improvement dollars are actually spent (i.e., actual pavement preservation and improvement projects). This research focuses on evaluating the Texas Department of Transportation’s (TxDOT) Pavement Management Information System (PMIS) to assess the agreement between its need estimates and actual construction projects at the district level. The research revealed there is little agreement between the output of PMIS’s Needs Estimate tool and actual construction projects. Possible reasons for this disagreement include the inability of PMIS’s Needs Estimates to consider the decision makers preferences and priorities, and also its inability to consider multiple years of condition data simultaneously. Through the use of the Analytic Hierarchy Process (AHP), the research was able to capture the effect of several variables on the decision making process. Using this method, pavement project suggestions were created that more closely matched actual projects than what the current Needs Estimate tool suggests. The projects selected using the new method were then tested against actual construction within three counties of the Bryan district. The new method closely matches actual preservation decisions made by the district within these three counties.

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