2009 - USA - Effectiveness of Treatment Lives/Survival Curves

The pavement analysis in this study considers various combinations of pavement rehabilitation treatments (two-course HMA overlay with or without surface milling, concrete pavement restoration, three-course HMA overlay with or without surface milling, three-course HMA overlay with crack and seat of PCC pavement and 3-R and 4-R overlay or replacement treatments). Six road functional classes (rural and
urban of interstates, non-interstates of the NHS, and non-interstates non-NHS) are considered. This allows for estimation of the performance and service life of the pavement, corresponding to each treatment and road functional class. Main findings;

• More than 95 percent of the data points of the RUT pavement performance indicator were below 0.5 inches indicating that this type of distress has become relatively rare on INDOT highways.
• Data points of the PCR were scattered in a very narrow range (between a PCR value of 70 and 100) compared to the scatter of the IRI and deflection. Consequently, distinct thresholds can be obtained from the wide scatter of the IRI and the deflection. This suggests that IRI and deflection are more reliable performance measures than PCR when programming pavement rehabilitation treatments.
• Two-course hot mix asphalt, HMA, overlay (with or without surface milling) treatments were found to have a forecasted
average annual deterioration in IRI of roughly 6 in/mi.
• Three-course HMA overlay with or without surface milling treatments were found to have a forecasted annual average
deterioration in IRI of about 5 in/mi. Three-course HMA overlay with crack and seat of PCC pavement treatments were found
to have a forecasted average annual deterioration in IRI of roughly 4 in/mi. Pavement projects identified as 3-R and 4-R overlay or replacement treatments were found to have a forecasted average deterioration in IRI in the range of 4 to 5 in/mi. Concrete pavement restoration treatments were found to have a forecasted average annual deterioration in IRI of roughly 7 in/mi.
• Average service life of two-course HMA overlay (with or without surface milling) was found to be roughly 10 years; 12 years for concrete pavement restoration; 12 years for three-course HMA overlay (with or without surface milling); 15 years for threecourse HMA overlay with crack and seat of PCC pavement; and 15 years for 3-R and 4-R overlay or replacement treatments. These numbers match closely with the estimated service lives in the current INDOT design manual.
• Unit cost of pavement rehabilitation treatment was strongly correlated (with a high degree of statistical confidence) to the
service life prediction and consequently was used in the performance prediction models.