Transition from manual to automatic rutting measurements : effect on pavement serviceability index values.

PDFTech ReportReport no. NM08SAF-02RuttingMeasuring methodsPavement performanceRuts (Pavements)New MexicoNew Mexico. Dept. of TransportationBandini, PaolaPham, Hung V.New Mexico State UniversityNew Mexico. Dept. of Transportation. Research BureauUnited States. Federal Highway AdministrationUS Transportation CollectionThe Pavement Serviceability Index (pSn is used by New Mexico Department of Transportation(NMDOT) to express the serviceability level of a pavement section at the network level. The PSIis calculated with distress ratings (including rutting) and roughness data. Currently, rut depthdata collected with two NMDOT-owned 3-point profilometers are not used as an input in thecalculation of PSI values. The main goal of this project was to develop and recommend aprocedure to substitute automated rut depth for rutting ratings from manual surveys. For planningand reporting purposes, it is important for NMDOT to maintain the consistency of the methodsand data used to calculate PSI values and to docwnent any change implemented so thatcomparisons of current and past conditions and performance evaluations of the network can bemade. The transition from using manual survey ratings to automated rut depth measurementsshould introduce the smallest possible difference in the calculated PSI values and the overallcondition rating of the highway network. Three procedures or approaches are presented anddiscussed. Regression analyses were applied to the rut depth and PSI data. RecommendedApproach A proposed preserving the current PSI formulation and factors and converting theautomated rut depth data into equivalent rutting ratings. Alternative Approach B proposed minormodifications to the PSI formulation. A third approach (Approach C) was considered andevaluated, but was not recommended. Results of the statistical tests performed on the data andresults are also presented. The ratings from manual surveys and automated rut depth data werecompared with detailed measurements of transverse profiles to evaluate the data from these twomethods. This report includes an implementation plan for the recommended and alternativeapproaches