Replacement of Rolling Straightedge with Automated Profile Based Devices

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CAIT project no.: 67 RU790

Fiscal Year: 1998/1999

Status: Final

Rutgers-CAIT Author(s): Nenad Gucunski, Ali Maher, Patrick J. Szary

External Author(s): Sameh Zaghloul, Nicholas Vitillo



A study was performed to evaluate the applicability of using automated highway profilers to replace the Rolling Straightedges (RSE’s) currently used by NJDOT to implement the department smoothness specifications. Two categories of profilers were considered in the study, low speed profilers (2 devices) and high speed profilers (3 devices), in addition to two of NJDOT RSE’s. The scope of the study was limited to asphalt surfaced pavements. Three levels of initial smoothness were considered in the study, very smooth, smooth and relatively rough pavements.

Several analyses were performed on the collected data. These analyses included; preliminary analysis, RSE simulation, statistical analysis, effect of speed analysis and correlation analysis. The preliminarily analysis was performed on the results of the RSE inspection to select test sections that match the study requirements. RSE simulation analysis was performed on the collected profiles to simulate the RSE inspection. This analysis consisted of driving a 10-ft straightedge over the profile and calculate the tolerance at the mid-point of the straightedge and then calculate the Percentage Defective Length (%DL).

Several statistical analyses were performed on the collected and simulated data to investigate the equipment repeatability and the differences among devices, including the two RSE’s. In these analyses, the F-Test and the Student T-Test were used. The analyses were performed on the %DL measured with the RSE’s and that resulted from the simulation analysis, as well as on the IRI measured using the automated profilers. The effect of speed analysis was performed on the data collected using the light weight profilers and the high speed profiler. Three correlation analysis studies were performed on the collected data. The objectives of these studies are to correlate the RSE measurements with the results of the simulation analysis performed on the profiles measured using the automated devices, to correlate the IRI measured with different devices and to correlate the IRI and %DL of the same device.