Relating Pavement Condition Index and Present Serviceability Rating for Asphalt-Surfaced Pavements

In response to the two latest transportation funding authorization bills, the Moving Ahead for Progress in the 21st Century Act and the Fixing America’s Surface Transportation Act, rules that require the reporting of specific pavement condition measures have been developed and encoded into federal regulation. Pavement performance rules published to the federal register require the reporting of the International Roughness Index (IRI), percent cracking, rutting (for asphalt-surfaced pavements) and faulting (for jointed concrete pavements). Allowing that the measurement of the IRI on pavements with a speed limit below 40 mph is not expected to provide a reliable estimation of ride quality, the rules permit the reporting of the present serviceability rating (PSR) on these routes. However, many agencies do not measure the PSR or collect the slope variance data required to estimate the PSR. In light of not having the data required to directly estimate the PSR, this paper presents a model to estimate the PSR using data collected during a Pavement Condition Index (PCI) survey. Furthermore, this paper explores the reasons why pavements can have a good PCI and poor PSR and vice versa. The model presented in this paper provides a reasonable estimate of the PSR, though it is noted that agencies who wish to report PSR should conduct an updated assessment of rider satisfaction to develop a stronger correlation of PSR and PCI.