Development and implementation of Korea's first Percent within Limit (PWL) specification for road pavements

Abstract

For the acceptance of, and payment for, road pavements, a Percent within Limit (PWL) specification was developed and applied to highway asphalt overlays for the first time in Korea. This paper deals with this unprecedented attempt along with some practical concerns raised by both the contractors and the agencies. Specification development started with defining the size of a LOT that was divided into three to six sub-lots depending on the construction variables. Five Acceptance Quality Characteristics (AQCs) that are considered to affect pavement's performance were chosen to implement the specification, and current highway QC/QA manuals were utilized to set the tolerances and allowable limits of AQCs. This study proposed three scenarios with different number of AQCs to calculate the composite pay factors, and their impacts on the payments were compared. As a result, it was found that a scenario with five AQCs was deemed the most advantageous to the contractor. However, if variances (standard deviations) of AQCs are large, the money penalties would be imposed on the contractors. Among test sites considered in this study, about 10% payment reductions were resulted primarily due to the scattering of AQCs. Finally, measured standard deviations were used to verify the tolerances of selected AQCs proposed in the PWL specification.

Dynamic Quality Monitoring System to Assess the Quality of Asphalt Concrete Pavement

“…At present, the pass rate method is usually adopted as the measurement method for pavement quality but this method cannot fully consider the data distribution and overall trend. Compared with the pass rate method, the percentage within the allowable limit (PWL) method comprehensively considers the mean and standard deviation of the sample data [43,44], which can effectively reflect the fluctuation of the monitoring data.…”

A New Open Curve Detection Algorithm for Extracting the Laser Lines on the Road

“…It directly determines the vehicle's comfort and road safety. Traditional methods [1,2] of pavement roughness detection mainly rely on manual collection, and they have the disadvantages of high subjectivity, low efficiency and safety problems. In the past few years, with the development of information technology and automatic controlling, micro-measurement technology has advanced greatly in precision, and this makes the pavement roughness measurement accuracy can fully meet the requirements of high-grade highways, airport runways and so on.…”