Volume 37, Issue 2 (March 2009)
Sensitivity of Road Unevenness Indicators to Road Waviness
Currently used single-number indicators of longitudinal road unevenness suffer from their nonuniqueness due to the ignorance of waviness, which is the measure of wavelength distribution in road profile spectrum. Six single-number unevenness indicators were taken into account, viz. unevenness index, straightedge index, International Roughness Index for two velocities (80 and 120 km/h), spectral evenness index, and equivalent unevenness index. A simulation study was conducted, in which the waviness varied in the range from w = 1.5 to 3.5. In addition two representative road vehicles, a personal car and a truck, and three different travel speeds v = 60, 90, and 120 km/h were considered. The ranges of ten different vibration responses were established and related to the reference. The lowest sensitivity to varying waviness has been found for an equivalent unevenness index, which is the standard unevenness index multiplied by a correction factor accounting for the influence of waviness, and for IRI estimated for v = 120 km/h.