Evaluating Cost Effectiveness and Optimal Timing of Pavement Preventive-Maintenance Treatments in Wet-Freeze Climates

Preventive-maintenance treatments help preserve pavements and delay deterioration caused by traffic loads and environmental conditions. However, guidance is needed to ensure cost effectiveness of treatments, the benefit-to-cost ratio of different treatments applied based on time. In this study, the cost effectiveness of the thin overlay, slurry seal, crack seal, and chip seal methods applied at different times were evaluated using the regression model of performance curves from Long-Term Pavement Performance (LTPP) data. The cost effectiveness is found to depend on the type of treatment and the time of applications as well as the chosen benefit cutoff value. The benefit cutoff value is a predefined performance threshold limit of cracking, above which the pavement is not acceptable for use. For average climate, traffic, and pavement conditions, the highest cost effectiveness corresponding to treatment ages of 1, 4, 7, 10, 13, and 16 years were found to be at benefit cutoff values of 150, 150, 200, 250, 300, and 300 m, respectively. When treatment is applied at 1, 4, or 7 years, crack seal is found to give the maximum cost effectiveness, and if treatment is applied at 10, 13, or 16 years, chip seal is found to give the maximum cost effectiveness. Comparison of all the benefit-to-cost ratios shows that the overall highest cost effectiveness is obtained when chip seal is applied at 16 years with a 300-m benefit cutoff value. When the annual average freeze index is 34 degrees C days, crack seal gives the maximum cost effectiveness if treatment is applied at 1, 4, 7, 10, or 13 years. On the contrary, if treatment is applied at 16 years, slurry seal is found to give maximum cost effectiveness. When annual average freeze index is 1,699 degrees C days and annual average daily traffic is 450, chip seal gives the maximum cost effectiveness irrespective of treatment ages. When annual average daily traffic is 7,933 at all treatment ages, crack seal gives the maximum cost effectiveness. (C) 2020 American Society of Civil Engineers.