Hilbert-Huang transformation (HHT) based texture profile analysis for continuous friction characterisation of pavements

Continuous friction measurement equipment (CFME) has been demonstrated as an appropriate method to acquire friction around the critical slip ratio for the Pavement Friction Management (PFM) programme. Through a comprehensive field data collection on testing sites with different preventive maintenance (PM) treatments, this study assessed the influences of various characteristics on the CFME measurements. Field friction data were collected by a Grip Tester, one type of CFME, and the corresponding texture profiles were acquired by a high speed texture profiler. For each testing site, friction data was measured under nine operational conditions with three water film depths and three testing speeds. An adaptive signal processing technique, Hilbert-Huang Transformation (HHT), was applied to extract amplitude and instantaneous frequency of profiles as the texture parameters. Subsequently, the HHT texture parameters, along with pavement conditions and testing operational characteristics, were deployed as the influencing factors for the development of statistical friction model. The results reveal that the CFME measurements are most sensitive to the change of water film depth and pavement surface texture properties. This study is anticipated to gain a better understanding of the characteristics of CFME measurements and implement CMFE to support PFM programme effectively.