Evaluation of Trapezoidal Shaped Grooves

In figure 14, the water source hose and waste collection hose are visible as the machine begins a new groove lane.

Figure 14. Groove-Cutting Machine With Water Supply Hose Cutting the grooves was performed in a south-to-north direction only. In figure 15, south is to the right and north to the left for reference. Each lane measured 55 ft in length. At the end of each run, the machine lifted the blade mechanism and stopped the flow of water. The vehicle then reversed direction and traveled back to the south side of the pavement. The driver aligned the machine for the next lane cut making sure to space the blades appropriately from the last groove in the previous lane. Cutting each groove lane, i.e., 55 ft in length, took about 4 1/2 minutes including return travel to the south side. The average cutting time was the same for both the trapezoidal-shaped grooves and the standard grooves at a rate of about 32 ft per minute. The contractor explained that the speed was faster than expected when cutting older pavement, as the pavement in the NAPTF was softer and much easier to cut.

Figure 15. Trapezoidal-Shaped and Standard Grooves in Asphalt Pavement at NAPTF

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