Evaluation of Trapezoidal Shaped Grooves

INTRODUCTION In response to an unsolicited proposal submitted to the Federal Aviation Administration (FAA) in July 2004, the Airport Safety Technology Research and Development (R&D) Branch at the FAA William J. Hughes Technical Center in Atlantic City, New Jersey, recommended an evaluation of a new trapezoidal pavement groove configuration. The FAA Office of Airport Safety and Standards, AAS-100, FAA Headquarters, Washington, DC, supported the Airport Safety Technology R&D Branch conducting an in-depth evaluation of the merits of the proposed new trapezoidal-shaped groove configuration. This report covers a multiphase assessment of the performance of the proposed trapezoidal-shaped groove configuration as viewed from the standpoint of past test and evaluation history and present work. The proposed configuration consists of a trapezoidal-shaped groove shape, 1/2 in. at the top, 1/4 in. at the bottom, and spaced 2 1/4 in. center to center. The FAA standard groove configuration, which is described in the FAA Advisory Circular (AC) 150/5320-12C [1], is a 1/4-in.- by 1/4- in.-square groove, spaced at 1 1/2 in. center to center (figure 1). Grooves are installed across the runway surface; transversely to the runway length and perpendicular to the runway centerline.

1 4 "

1 4 "

1 1

4 "

Standard FAA groove pattern

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2 " typ.

NOT TO SCALE

1 2 "

1 3

1 4 "

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Proposed alternate groove pattern

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2 1

4 " typ.

Figure 1. Standard and Trapezoidal-Shaped Groove Configurations Pavement grooves have been scientifically proven to minimize aircraft hydroplaning during both takeoff and landing operations under rainfall conditions and have performed well when installed in both rigid (Portland cement concrete) and flexible (hot mix asphalt) pavements. Saw-cut grooves deteriorate over time from repeated interaction with aircraft traffic, as well as from additional interaction with pavement maintenance activities such as rubber removal, sweeping, and snowplowing operations. Trapezoidal-shaped grooves were not included in any of these pre- 2004 studies due partly to practical limitations in saw blade manufacturing and design technology. In the unsolicited proposal, it was suggested that different geometries for saw blades were now feasible and could be manufactured through a new manufacturing process. The contractor developed a diamond-surfaced rotary blade that had a trapezoidal-shaped design and had

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