Life-cycle cost analysis of pavement preservation techniques in Texas
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The proper implementation of pavement preservation techniques can extend the life of a pavement structure in a cost-effective manner. For this reason, a large part of the Texas Department of Transportation (TxDOT) annual budget is assigned to the maintenance and rehabilitation of the State highway network. Within this budget, a fair share is allocated to the implementation of preventive maintenance (PM) techniques, whose timely application has proved the best approach to keep the pavement sections in “Good” or “Very Good” condition. The main objective of this research study was to develop a probabilistic life-cycle cost analysis (LCCA) that allowed the evaluation and comparison of highway pavement sections subjected to one of the three main PM treatments used in Texas, namely, chip seals, microsurfacing and thin overlays. Effective life and the cost per mile lane were the main variables used to develop the analysis. The analysis was performed through Monte Carlo Simulation using data from TxDOT databases containing historical information on more than 14,000 projects constructed between 1994 and 2016. Because TxDOT maintains a plethora of information on its databases, the methodology to use those databases and to extract the relevant information used in this study was also described. During the study, the effect of the facility type, traffic volume and traffic loads on the treatments were also analyzed. Based on the results of the analysis, it was established that all three treatments present a similar service life regardless of external factors, but have different costs, with chip seals having the lowest, followed by microsurfacing and thin overlays. Findings suggest that chip seals have the most cost-effective LCC, even in environments where they are not commonly employed, like heavily trafficked sections. However, microsurfacing emerges as an interesting alternative as traffic volumes and traffic loads increase. Finally, thin overlays are to be evaluated in a case-by-case basis as they have the less predictable behavior. This is most probably consequence of being the newest type of treatment, having the steepest learning curve. They could work well in pavement sections located in intersections, turning points and stop signs, where higher shear stresses are involved.