The most extensive highway research project in history has been completed with the release of pavement performance findings resulting from the AASHO (American Association of State Highway Officials) National Road Test conducted in Illinois. The purpose of the test program was to measure and record the effects of two years of truck traffic on concrete and asphalt test pavements and on bridges. The data offers dramatic proof of the marked superiority of concrete pavements over asphalt pavements for the full range of axle loadings covered by the tests. Almost 75 percent of the concrete sections survived 1,114,000 axle load applications, whereas only 24 percent of the asphalt sections are listed as surviving. The average final serviceability index for surviving sections of concrete pavement ranged from 4.0 to 4.2 (very good); the range for asphalt sections varied from 2.5 (fair) to 3.1 (good), with good rating applicable to only the lightest axle loadings.