Measurement of acoustic roughness

Use of CAT to measure acoustic roughness

The same CATs that are routinely used for reprofiling work are used to show that irregularities on sites comply with the requirements of EN ISO 3095 (“Measurement of noise emitted by railbound vehicles”) and EN 15610 (“Rail roughness measurement related to rolling noise generation”). The CAT is widely used by acoustics consultancies, research organisations and vehicle suppliers for these purposes.

The CAT software includes standardised algorithms for “pit-and-spike” removal and “wheel curvature processing” and also the standardised presentational format for calculations of one-third octave spectra.

CAT acoustic roughness

Measurements of two rails over a standard 100m test site, showing irregularities in 10-30mm wavelength range (above) and one-third octave spectra (below).  Measurements have been processed using “pit-and-spike removal” and “wheel curvature processing” algorithms.  The site complies with the requirements of EN15610:2009.  The spectra are shown for the wavelength range 3.15-2000mm, whereas EN15610 requires calculation only for the wavelength range 3.15-250mm at most.  Longer wavelengths cannot be measured using straight-edge based equipment, but can be measured using the CAT.