ASSESSING THE STRUCTURAL CONDITION OF FLEXIBLE PAVEMENTS

THE LIFETIME OF A FLEXIBLE PAVEMENT IS A COMPLEX CONCEPT; THEREFORE THERE ARE MANY DEFINITIONS, IN WHICH SEVERAL MEASURABLE QUALITIES ARE USED. EVENNESS IS IMPORTANT FOR RIDING COMFORT AND SAFETY, RUT DEPTH FOR COMFORT AND AQUAPLANING, AND CRACKS AND PATCHES INDICATE THE ONSET OF DESTRUCTION, AS DO LARGE NON RESILIENT DEFLECTIONS. SEVEN EVALUATION-METHODS ARE MENTIONED AND DISCUSSED. THE PSI-METHOD (FROM THE AASHO-TEST) IS NOT SATISFACTORY, SINCE THE PSI. THE UTAH-METHOD RELIES ON THE PSI-METHOD. LECLERC AND MARSHALL'S METHOD TAKE ACCOUNT OF THE ROAD AUTHORITY AS WELL AS THE USER. SCRIVNER AND HUDSON DESIGNED A "TEXTUROMETER" TO FIND THE PSI. STATENS VAGINSTITUT (SWEDEN) APPLIES THE THICKNESS-INDEX FROM THE AASHO-TEST. WILLIAMS TAKES A WALK AND A DRIVE ALONG THE ROAD AND ESTIMATES A FIGURE ACCORDING TO WHICH PSI IS CALCULATED. THE PUBLIC ROADS METHOD IS BASED ON AASHO RESULTS; DIAGRAMS ARE USED. NONE OF THESE METHODS ARE SATISFACTORY. THE AIM IS TO FIND A METHOD WHICH CONSIDERS ALL RELEVANT FACTORS, INCLUDING SKID-RESISTANCE AND REFLECTION OF THE SURFACE.