Acceptability of Pavement Roughness on Urban Highway by the Driving Public

This paper explores the driving public’s attitude toward acceptable levels of road roughness using empirical data collected on urban highways. Individual driver acceptability levels are matched with International Roughness Index (IRI) levels to examine the existence of potential user acceptability thresholds. In particular, the observed trends are compared with the federal IRI guideline of 170 in/mi (2.68 m/km) for “acceptable ride quality,” recommended by the Federal Highway Administration (FHWA) in its 1998 National Strategic Plan for the National Highway System (NHS). This paper provides empirical support for the current recommended guideline. The research seems to provide the empirical support for the federal IRI guidelines that are already in existence. This study also found that IRI levels provided a very good indication driver acceptability, which agrees with past research based on antiquated present serviceability ratings (PSR).