Effect of Air Temperature, Vehicle Speed, and Pavement Surface Aging on Tire/Pavement Noise Measured with On-Board Sound Intensity Methodology
The study of the traffic noise as an environmental impact, the search for solutions to this problem, and the development of noise measurement methodologies that help in the search of these solutions, is now a fundamental responsibility for the transportation industry.
So, in line with this responsibility, consistent work was made with focus on tire/pavement noise measured over different pavement surfaces, and under different environmental conditions, and different speeds. In a parallel way, work was conducted for the development, improvement, and practical use of the On- Board Sound Intensity (OBSI) methodology for tire/pavement noise measurements.
The first part of this thesis shows the results of field experimentation about the influence of external factors like air temperature and vehicle speed over the tire/pavement noise measured with the OBSI methodology. Temperatures from 40 to 90"F were targeted, and speeds from 35 mph to 60 mph (range in which tire/pavement noise becomes predominant for the overall vehicle noise) were tested. For this work a series of seasonal field tests were conducted on a primary road in Virginia over various months. The results were analyzed to quantify the variation of tire/pavement noise with respect to the air temperature and test speed, and therefore to find correction factors for this variables in order to normalize the data taken under different conditions.
In the second part of this thesis, the study of tire/pavement noise over different surfaces and measured over a timeframe of three seasons is presented. This part presents results about noise reduction potentials of two proposed "quiet" concrete technologies and 3 proposed "quiet" asphalt surfaces when compared with one another, and with control sections. Also the second part of the thesis includes results about the susceptibility of the proposed surfaces to external factors such as: aging (three seasons involved), air temperature differentials and winter maintenance.
In general, the findings show trends that tire/pavement noise slightly decreases as air temperature increases. A gradient of approximately -0.05 dBA/"F was found. It was found as well that tire/pavement noise increases an average of 2.5 dBA for every 10 mph of increased speed.
The statistical analysis results for the second part of the thesis shows that all proposed concrete surfaces and asphalt surfaces present benefits in terms of noise reduction, For the asphalt surfaces, it was found that more voids in the surface helps to absorb the noise. In addition, the rubber modified mixes show an improved noise reduction potential. Air temperature normalization was performed an a statistical analysis was conducted; it was found that air temperature has a significant influence in the noise measurements especially for the first months of use. Finally it was found that there is a slightly increase in noise over time after the first months of use.