Design of a Randomized Tining Rake for Portland Cement Concrete Pavements Using Spectral Analysis

Uniformly spaced, transverse-tined portland cement concrete (PCC) pavements have been in extensive use in the United States since the early 1970s. However, driving on tined pavements generates an uncomfortable acoustic “whine”that has a discrete frequency. Recent research by the Wisconsin Department of Transportation (WisDOT) and FHWA led to an interim guideline for randomization of the tining pattern. The guideline called for tine spacing varying from 10 to 40 mm, with 50 percent of the spacing below 25 mm. At least five states have experimented with this random pattern, with limited success in eliminating the whine. A study was completed recently as part of a WisDOT contract with Marquette University and the HNTB Corporation, and funded by FHWA, to analyze all of the pavements. The tonal properties of acoustical noise were related to the serial arrangement of the tining, showing that the frequencies can be predicted from the power spectrum of the series of tines. A method of designing the series of tines that minimizes and possibly eliminates the presence of these whines is proposed and explained. By predicting the tonal properties of acoustical noise at the rake-design stage, the construction effort in building and researching noise and texture characteristics is substantially reduced. A random rake, designed using the proposed methodology, has been used in tining a road section, and preliminary spectral analysis of the acoustic noise revealed no tining-related discrete tones.