The amount of rutting on flexible pavements is an important distress parameter to consider when making judgements about rehabilitation of the riding surface. Because severe rutting is dangerous and uncomfortable to the riding public, millions of dollars are spent each year in the United States on rehabilitation of pavements that show such structural deterioration. Thus, network-level decisions about which pavements to rehabilitate should be based on a quantitative rut index that best uses available dollars while protecting the safety of the driving public. The methodology used to develop such a quantifiable rut index for Texas is presented. The Texas Department of Transportation has been collecting rut information by means of survey teams that manually read and record rut-depth information at selected sites throughout the state. The recent purchase of an Automatic Road Analyzer (ARAN) unit (and its associated rut bar) now allows them to collect rut information under traffic conditions and at normal highway speeds. The Center for Transportation Research was contracted to evaluate the ARAN unit and help implement the study findings. The methodology used in developing a rut index based on data collected by the ARAN unit is presented. The conclusions are based on the ARAN's output, but the methodology and index can be applied to any rut-depth instrument that collects and presents rut data in a similar fashion. (A)
Abstract