Evaluation of Trapezoidal Shaped Grooves

x

Figure 17. Wheel Tracks and Profile Data Zones Figure 17 also includes a section labeled “Trafficked Portion,” illustrating the wheel paths of the test machine wheel assembly, running left to right across the grooved sections. As discussed in the NAPTF test description section, the wheel assembly is programmed to distribute loadings in a manner that closely represents the concentration of wheel loadings that an actual runway pavement would experience based on pilot deviation from the centerline. Therefore, the largest concentration of passes is designated by the x in figure 17. Wheel paths on either side of the middle one represent progressively fewer passes according to the appropriate distribution. The data in table 2 shows the dates and number of wheel assembly passes at the time of the profile measurement. In total, 10,362 runs were made across the groove installations. Figure 18 defines the terminology used in table 2. An analysis of the data in table 2 showed that after the standard and trapezoidal-shaped grooves were exposed to 10,362 operations, both grooves experienced some degree of distortion from the heavy wheel loading. The trapezoidal-shaped grooves, however, maintained their shape and height better than the standard grooves. As shown in the data in table 2, the standard groove was

20