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o' CTA &GO Countywide Pavement Management Plan Guidelines <br />Local Tax Dollars at Work <br />Prequalification/Calibration of Inspectors <br />Prequalification or calibration of inspectors ensures that proper procedures are followed and that <br />the results obtained are within acceptable variability ranges. This will be implemented by OCTA. <br />Briefly, the procedures to prequalify or calibrate inspectors are as follows: <br />a. OCTA will select approximately 20 pavement sections to be used as control or test sites. <br />Collectively, the control sites should exhibit common distress types and levels of severity <br />that will be encountered in the pavement network and should be across all functional <br />classes, pavement age, surface type, pavement condition and distresses. <br />b. Inspect the sections manually (walking survey) using at least two different experienced <br />inspectors and the established survey protocols (Appendix A and ASTM D6433), including <br />any modifications. This will establish the baseline PCI for each control section. <br />C. The candidate inspectors should then survey the same pavement sections within one <br />month of the control surveys established in Step (b). The data for the sections should be <br />collected and submitted to OCTA as soon as they are completed. <br />d. OCTA will calculate the PCIs based on the survey data collected by inspectors. <br />e. Compare the control PCI data with survey results by candidate inspectors. Identify the <br />differences and areas of variability. <br />Acceptability Criteria <br />The criteria for acceptability are: <br />a. nRMSE 5 1.4 where: <br />n RPCII — BPCII z <br />nRMSE = 1 SDPCI <br />n <br />Where: <br />nRMSE = Normalized root mean square error or deviation <br />RPCI; = Reported PCI for control section i <br />BPCI; = Baseline PCI for control section i <br />n = Number of control sections <br />and <br />SDPCI = <br />100 + 3(5.29 — BPCI) <br />5.29 <br />b. Inspectors that obtain nRMSE values higher than 1.4 will be allowed to re -inspect and <br />re -submit PCI values for three control sections. OCTA will indicate the three control <br />sections where the inspectors showed the highest deviations from the baseline survey. <br />Re -inspections are allowed only once. The normalized root mean square error (nRMSE) <br />will be recalculated and the criteria described at point (a) applied. <br />c. All inspections must be performed independently by each inspector. <br />Effective March 2024 2-7 <br />