Correlation Between NJDOT Condition Status Rating and Federally-Mandated Condition Ratings / New Jersey DOT
NCHRP Web-Only Document 358, which is a supplemental report to the Guide to Effective Methods for Setting Transportation Performance Targets, provides examples documenting how target-setting methods are being used by various transportation agencies. One of the examples illustrates how the New Jersey DOT piloted the use of a scenario analysis approach for setting its pavement infrastructure condition targets. An important consideration in the use of this approach was the availability of a pavement management system (PMS) capable of forecasting future pavement conditions. However, the New Jersey DOT had not established prediction models for the Federal cracking metric, so methods were developed to correlate forecasted conditions from existing models to the Federally-required cracking metric. Correlations were developed using three years of condition data collected in accordance with both the agency’s legacy Condition Status rating and the Federal measures in 0.1-mi segment lengths. Using both sets of data, correlations were developed based on the likelihood that a pavement section rated “Good” using the agency’s CS rating would also be classified as a “Good” pavement using the Federal definitions. The correlations found that 88.43 percent of the segments were rated “Good” based on both approaches (Grant, M., et.al. 2023B). A similar approach was used to correlate “Poor” conditions, but the analysis showed more variability in correlating segments at this condition level. To address the variability, New Jersey DOT decided to use 3-year averages to establish the final correlations, which are presented below (Grant, M., et.al. 2023B).
Table 6.A - Correlation between NJDOT CS and Federally-mandated condition ratings (Grant, M., et.al. 2023B)
| Federal Good | Federal Fair | Federal Poor | |
|---|---|---|---|
| NJDOT Good | 87.5% | 13.78% | 0.00% |
| NJDOT | 23.74% | 76.25% | 0.01% |
| NJDOT | 6.36% | 86.02% | 7.62% |
The correlations were applied to the predicted conditions generated by the PMS to determine the expected conditions using the Federally-mandated performance measures. Several scenarios were generated, allowing the NJDOT to use the results to set realistic Federal targets.
Read more in the chapter: 6.1.3 Target Setting Methods