// multi-utility computation suite · offline · instant · precise
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eng.pavement-IRI-roughness Calculator
Calculates the International Roughness Index (IRI) from road profile measurements and classifies pavement condition. IRI below 2.0 m/km is smooth (new road); above 4.0 m/km is rough and requires maintenance — IRI is the standard pavement management performance metric.
Inputs
Psi Initial
Reference formula or conversion factor shown for context.
Psi Terminal
Reference formula or conversion factor shown for context.
Sn
Count of items or occurrences.
Esal Millions
Reference formula or conversion factor shown for context.
Results
design ESAL capacity W18
Sample size or count used in the calculation.
estimated IRI (m/km)
The value at the specified point or condition.
AASHTO 1993 design equation
The value at the specified point or condition.
PSI loss ΔPSI
The decrease or degradation from the baseline.
IRI ≈ 3.5·exp(0.47·(PSI₀−2.5))
Reference formula or conversion factor shown for context.