IRI Threshold Values Based on Riding Comfort

Abstract

Road surface roughness is an important indicator for evaluating the service quality and performance of asphalt pavements; the traditional evaluation index for this indicator is the international roughness index (IRI). In this study, in order to comprehensively evaluate the riding comfort induced by pavement roughness, indoor laboratory tests and field tests were conducted on the threshold value of the IRI. The laboratory tests used a driving simulation chamber, and the field tests used 12 typical roads in the Miyun District in Beijing, China. Three different evaluation techniques were used: a questionnaire; a vibration acceleration method (aw, the weighted root-mean square acceleration); and a psychological and physiological index root-mean square of the successive differences (RMSSD) method. The evaluation techniques were employed in order to analyze the threshold value of the IRI for both the laboratory and the field tests. The evaluation revealed two significant results. For a constant driving speed, as the IRI value increased, the evaluation indicator aw increased, and the value of the RMSSD decreased linearly. For a constant IRI value, as driving speed increased both the evaluation indicator aw and the RMSSD value increased. Furthermore, the fitting results showed that the correlation coefficient R2 between the IRI and the driving speed reached 0.9525 for the outdoor test, indicating a high relativity. The methods for the evaluation of the IRI threshold value that were explored in this study are very promising, having the potential to improve pavement construction and maintenance efforts.