IRI
International Roughness Index (IRI) means a statistic used to estimate the amount of roughness in a measured longitudinal profile. The IRI is computed from a single longitudinal profile using a quarter-car simulation, as described in the report: On the Calculation of IRI from Longitudinal Road Profile (Sayers, M.W., Transportation Research Board 1501, Transportation Research Board, Washington, DC 1995).
Source
23 CFR § 490.305
Scoping language
The following definitions are only applicable to this subpart, unless otherwise provided: