ISO/TC 43/SC 1/WG 39 - Characterization of pavement texture using surface profiles

This document describes a test method to determine the average depth of pavement surface macrotexture (see Clause 3) by measuring the profile of a surface and calculating the texture depth from this profile. The technique is designed to provide an average depth value of only the pavement macrotexture and is considered insensitive to pavement microtexture and unevenness characteristics. The objective of this document is to make available an internationally accepted procedure for determination of pavement surface texture depth which is an alternative to the traditionally used volumetric patch technique (generally using sand or glass beads), giving comparable texture depth values. To this end, this document describes filtering procedures that are designed to give the best possible representation of texture depths determined with the volumetric patch method[13]. Modern profilometers in use are almost entirely of the contactless type (e.g. laser, light slit or light sheet, to mention a few) and this document is primarily intended for this type. However, this does not exclude application of parts of it for other types of profilometers. This ISO 13473 series has been prepared as a result of a need identified when specifying a test surface for vehicle noise measurement (see ISO 10844:2014[6]). Macrotexture depth measurements according to this document are not generally adequate for specifying test conditions of vehicle or traffic noise measurements, but have limited applications as a supplement in conjunction with other ways of specifying a surfacing. This test method is suitable for determining the mean profile depth (MPD) of a pavement surface. This MPD can be transformed to a quantity which estimates the macrotexture depth according to the volumetric patch method. It is applicable to field tests as well as laboratory tests on pavement samples. When used in conjunction with other physical tests, the macrotexture depth values derived from this test method are applicable to estimation of pavement skid resistance characteristics (see e.g. Reference [15]), estimation of noise characteristics and assessment of the suitability of paving materials or pavement finishing techniques. The method, together with other measurements (where applicable), such as porosity or microtexture, can be used to assess the quality of pavements. This document is adapted for pavement texture measurement and is not intended for other applications. Pavement aggregate particle shape, size and distribution are surface texture features not addressed in this procedure. The method is not meant to provide a complete assessment of pavement surface texture characteristics. In particular, it is known that there are problems in interpreting the result if the method is applied to porous surfaces or to grooved surfaces (see Annex B). NOTE Other International Standards dealing with surface profiling methods include, for example, References [1], [2] and [3]. Although it is not clearly stated in these, they are mainly used for measuring surface finish (microtexture) of metal surfaces and are not intended to be applied to pavements.

ISO 13473-5:2009 specifies procedures for determining the average depth or level of pavement surface megatexture by measuring the profile curve of a surface and calculating megatexture descriptors from this profile. The technique is designed to give meaningful and accurate measurement and description of pavement megatexture characteristics for various purposes. Since there is an overlap between megatexture and the surrounding ranges, the megatexture descriptors unavoidably have a certain correlation with corresponding measures in those ranges. ISO 13473-5:2009 specifies measurements and procedures which are in relevant parts compatible with those in ISO 13473-1, ISO 8608 and EN 13036-5.

ISO/TS 13473-4:2008 describes the methods that are available to perform a spectral analysis of pavement surface profile signals. It specifies three possible methods for spatial frequency analysis (or texture wavelength analysis) of two-dimensional surface profiles that describe the pavement roughness amplitude as a function of the distance along a straight or curved trajectory over the pavement. The result of the frequency analysis will be a spatial frequency (or texture wavelength) spectrum in constant-percentage bandwidth bands of octave or one-third-octave bandwidth. ISO/TS 13473-4:2008 offers three alternative methods to obtain these spectra: 1) analogue constant-percentage bandwidth filtering; 2) digital constant-percentage bandwidth filtering; 3) constant narrow bandwidth frequency analysis by means of Discrete Fourier Transform, followed by a transformation of the narrow-band spectrum to an octave- or one-third-octave-band spectrum. The objective of ISO/TS 13473-4:2008 is to standardize the spectral characterization of pavement surface profiles. This objective is pursued by providing a detailed description of the analysis methods and related requirements for those who are involved in pavement characterization, but are not familiar with general principles of frequency analysis of random signals. These methods and requirements are generally applicable to all types of random signals.

ISO 13473-3:2002 specifies requirements for profilometers used in pavement engineering in order to give meaningful and accurate measurement of micro-, macro- and megatexture characteristics of paved road and airfield surfaces. It also includes schemes for the classification of such profilometers with respect to their use and overall accuracy. The profilometers may be of any operational type. The scope of ISO 13473-3:2002 does not include profile analysis of machined surfaces. Also excluded from the scope is the profile analysis of road unevenness.

ISO 13473-2:2002 defines terms, expressions and parameters that are related to the analysis of pavement texture, on roads as well as on airport runways and taxiways. In particular, it defines terms and expressions related to profile representations of texture, which are anticipated to be useful in modelling of pavement characteristics such as tyre/road noise emission, tyre/road friction, tyre rolling resistance and tyre wear. In addition, some brief general information on pavement surface characteristics and their effects is presented. ISO 13473-2:2002 also contains some basic requirements in connection with the use of the terms, expressions and parameters. Profile analysis of machined surfaces is not included, since this subject is dealt with in other International Standards, for example ISO 3274, ISO 4287, ISO 4288, ISO 5436-1 and ISO 12085. Profile analysis of road unevenness, which is dealt with in ISO 8608, is also excluded.