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Roughness progression for a road in Texas, US. Blue dots show the times of maintenance. The international roughness index (IRI) is the roughness index most commonly obtained from measured longitudinal road profiles. It is calculated using a quarter-car vehicle math model, whose response is accumulated to yield a roughness index with units of ...
A topographic map of Stowe, Vermont with contour lines This false-color satellite image illustrates topography of the urban core of the New York metropolitan area, with Manhattan at its center. Topography is the study of the forms and features of land surfaces .
An often used definition for asperities in geotechnical engineering: Unevenness of a surface are asperities if these cause dilation if two blocks with in between a discontinuity with matching asperities on the two opposing surfaces (i.e. a fitting discontinuity) move relative to each other, under low stress levels that do not cause breaking of the asperities.
The present serviceability index (PSI) is a pavement performance measure.Introduced by the American Association of State Highway and Transportation Officials (AASHTO), the PSI is one of the most widely used pavement performance indicators after pavement condition index (PCI) and international roughness index (IRI).
RMS in general is a statistical technique to define a representative value for a group of data points. With regard to surface roughness, it means that the heights of the individual microscopic peaks and valleys shall be averaged together via RMS to yield a measurement of roughness. See also herein f as a finish mark. RT or R/T
In engineering, the Moody chart or Moody diagram (also Stanton diagram) is a graph in non-dimensional form that relates the Darcy–Weisbach friction factor f D, Reynolds number Re, and surface roughness for fully developed flow in a circular pipe. It can be used to predict pressure drop or flow rate down such a pipe.
Surface roughness, often shortened to roughness, is a component of surface finish (surface texture). It is quantified by the deviations in the direction of the normal vector of a real surface from its ideal form. If these deviations are large, the surface is rough; if they are small, the surface is smooth.
The PSI is based on data on the road's longitudinal roughness, patchwork, rutting, and cracking. Later studies have shown that PSI is mainly a fruit of unevenness, with a correlation of more than 90% between the two. Unevenness was measured with a mechanical profilograph, reporting a parameter called slope variance (SV). SV is the second ...