National Highway System Pavement Condition

percent of NHS facility miles

Poor: IRI > 170

Fair: IRI 95 - 170

Good: IRI < 95


Pavement condition is measured by the International Roughness Index (IRI) which takes a longitudinal profile of pavement roughness based on one-way facility centerline miles. A lower IRI indicates smoother highway conditions and a higher IRI indicates rougher highway conditions.


U.S. Department of Transportation, Federal Highway Administration, Highway Statistics, table HM-47, available at

Last Updated: November 2020