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2.0 Methodology <br />Figure 2-1: Sample Pavement Deterioration Curve <br />100 <br />Very Good \ <br />85 — — — — — — <br />Good <br />75 — — — — — — <br />Fair <br />60+-----------------------`- <br />Poor <br />40�---- <br />Very Poor <br />0 <br />Pavement Life (yrs) <br />Do Nothing <br />— — — — — — Surface Seal — <br />Overlay <br />Resurfacing <br />Reconstruction <br />To develop an accurate PDC, "suspicious" data / anomalies outside of the maximum and <br />minimum envelopes generated from StreetSaver are filtered out. For example, data with PCI <br />increase significantly with age (recording error) or lack of past inspection data must be removed <br />because pavements are load carrying structures, which degrade over time due to the combined <br />action of environmental and traffic. This data filtering processing is critical because pavements <br />with unusual performance would have substantial impact on the PDC behavior and the pavement <br />life cycle consequently. <br />The final PDCs illustrate that the rate of deterioration is fairly slow in the early years of the <br />pavement's design life. During the first 65 percent to 75 percent of a pavement's design life, <br />which varies based on functional classifications and surface type, a pavement deteriorates <br />approximately 40 percent of its quality, i.e. from a PCI of 100 ("Very Good" condition) to a PCI of <br />60 ("Fair" condition). However, the rate of deterioration starts to increase rapidly with age after a <br />pavement reaches this point in its life cycle. Typically, a pavement can deteriorate 40 percent in <br />its quality (PCI quickly drops from 60 ("Fair" condition) to 20 ("Very Poor" condition)) in the next <br />15 percent to 25 percent of its design life. Although the local and arterial networks have different <br />design life spans, both PDCs share similar characteristics because the pavement will crack and <br />these cracks will propagate out and become severe with continued traffic loadings and weathering <br />without any M&R treatment. Therefore, a PCI of 60 is assigned as the critical PCI for both the <br />arterial and local networks. The critical PCI is defined as the PCI value after which a pavement <br />section is expected to deteriorate rapidly with age or where the rate of PCI loss increases <br />significantly with time. <br />City of Santa Ana 2024 Pavement Management Program 2-3 <br />