Evaluation of Trapezoidal Shaped Grooves

Table 1. Trafficking Schedule for Test Items

Load on North Lane* (lb)

Load on South Lane* (lb)

Dates (from-to) 07/07/05- 07/25/05 07/26/05- 08/12/05 08/15/05- 08/18/05 08/19/05- 08/24/05- 09/13/05- 10/06/05

Repetitions (from-to)

Test Items Trafficked** MRG-N, MRC-N, MRS-N MRG-S, MRC-S, MRS-S MRG-N, MRC-N, MRS-N MRG-S, MRC-S, MRS-S

1-5,082

4-wheel, 55,000 6-wheel, 65,000 6-wheel, 65,000 6-wheel, 65,000 6-wheel, 65,000

4-wheel, 55,000 4-wheel, 65,000 4-wheel, 65,000 4-wheel, 65,000 4-wheel, 65,000

5,083-11,814

11,814-14,256 MRG-N, MRC-NW, MRS-N MRG-S, MRC-S, MRS-S

14,257-16,302 MRG-N, MRS-N

MRG-S, MRC-S, MRS-S

16,303-25,608 MRG-N, MRS-N MRG-S, MRS-S

*Cold, unloaded tire pressures: 220 psi at 55,000 lb and 260 psi at 65,000 lb. **Test item identification specific to pavement test, not to this study.

N = North S = South NW = Northwest

DATA COLLECTION AND RESULTS. Data collection consisted of visual observation, photographs, and longitudinal profiles. The test machine was stopped for a relatively short time each day in order for researchers to take key measurements and perform any necessary maintenance. This provided researchers the opportunity to capture profile data. Figure 17 depicts one portion of the grooved pavement in the NAPTF. The image is not to scale but represents the north side of the centerline grooved section in transition T5. The grooves were cut transversely, i.e., perpendicular to the yellow centerline stripe at the top of the image. The loaded wheel assembly of the test machine traveled east and west across the grooves. The wheel paths are shown in the picture as lanes, which are shaded according to how many passes of the gear that section of pavement experienced. Profiles were taken within the region highlighted by green and orange boxes.

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