As well known, pavement texture intrinsic indicators may be divided into two different classes: aggregate and spectral ones. In the first set there are MPD, ATD, RMS, etc, while in the second one there are, for example, texture amplitude Power Spectral Density and texture amplitude levels. On the other hand, many experiences remark that extrinsic texture indicators (such as, for example, friction and outflow time), though measured in different manners, are not equally dependent on the various wave-lengths classes of texture amplitudes. So, when an Agency has measured service quality indicators based on aggregate texture parameters (for example Sand Height), it is not possible to be sure on friction or drenability requirements. So, it is not possible to say if safety essential conditions have been satisfied. According to these problems, in this paper, Authors have planned a set of experiments to study in deep the correlation among texture levels on different wavelengths and friction or outflow measures. Spectral levels have been obtained by amplitude profiles measured by a laser device, based on conoscopic olography, and a signal post-processing by a specific dedicated software. Friction measures have been effected by the British Pendulum while outflow times have been measured by a typical belgian outflow meter. The obtained results have remarked the specific influence of some particular wave-lengths on the above mentioned extrinsic parameters. For the covering abstract see ITRD E135448.
Abstract