scope:

Research Objectives: The objectives of this research project were to facilitate the process of comparing the performance of peer state DOTs using the IRI; prepare, analyze, and evaluate the performance data; and identify and document good practices related to achievement of smooth pavement. In addition to identifying causal links which may exist between network-level pavement smoothness and best practices, an important objective of this project was to facilitate future use of comparative analysis of pavement smoothness performance, by identifying analysis approaches and measurement techniques that can, over time, achieve a greater degree of consistency and comparability. While states measure pavement conditions in various ways, oft en using multiple indicators, this project was limited to comparisons of pavement smoothness on the Interstate System. This focus on the Interstate System eliminates much of the variability in IRI measurement that is related to measurement speed and speed changes, short segment lengths, and the presence of traffi c signals. It is important to note that some states employ diff erent pavement construction and management practices on Interstates than for other roadways, so the results of this research should be considered valid for Interstates only.