Rating City and County of Denver Urban Pavement Constructability Using a Profiler

Abstract

The international roughness index (IRI) was developed in 1986 to generate a longitudinal roadway profile analysis tool for asphalt surfaces. The IRI is typically applied to freeway and rural highway facilities where uninterrupted spans of asphalt are expected. The city and county of Denver (CCD) in cooperation with the University of Colorado Denver have examined the application of the IRI to urban roadway facilities. Elements of urban roadways that influence IRI values include drainage infrastructure and cross-street access. This paper details the equipment and methodology used to address challenges in assessing urban constructed roadways with the IRI. Repeatability studies were completed using five different inspectors involved in the data collection activities. The results indicated that repeatability varied between different inspectors by approximately 2%. A before-repair and after-repair study was completed on newly resurfaced roadways around the CCD in an attempt to establish a set of baseline values for the application of the IRI to urban roadways. The IRI values for a sample of 23 test cases showed a weighted average postpaving improvement of approximately 36%. Recommended urban IRI values for good and acceptable surfaces are suggested at 150 in./mi (2,367.44 mm/km) and 220 in./mi (3,472.24 mm/km), respectively.