2011 Volume 9 Pages 1376-1390
Although the inertial profiler has been introduced for decades, most of the highway agencies in Taiwan still adopt the 3-M straightedge as the main device for pavement roughness measurements. Through the Long Term Pavement Performance database, 5280 profile data were selected in this study for analyzing the relationship between international roughness index (IRI) and standard deviator (σ). The natural logarithm transformation was applied to both variables before a linear regression model was developed with R2 of 0.9368. However, it is found that the current smoothness acceptance specification (σ= 2.4 mm) used by Taiwan Freeway and Expressway system is equivalent to an IRI value of 2.97 m/km that is not rigorous enough while compared with that of other countries. It is recommended to modify the specification from 2.4mm to 1.1 mm that will perform an equivalent level of the IRI-based specification suggested by Federal Highway Administration.
