Development of tools to evaluate quiet pavements in the laboratory and field

Road traffic noise is becoming a major public concern. While there have been many claims of noise reduction from different agencies over the years, there was limited conclusive documentation and testing to support the claims. In late 2003, the University of Waterloo's Centre for Pavement and Transportation Technologies (CPATT) and the Regional Municipality of Waterloo embarked on a partnership to first design noise reducing pavement test sections and then secondly to conduct controlled noise testing on four different types of asphalt mixes. The four different surface courses were placed in lengths of 600m. The overall 2.4 km test area was closed to traffic and test vehicles were driven through the test area at different control speeds with sound level meters recording noise levels both at the tire/pavement interface as well as at monitoring stations off the roadway. Noise level test results have indicated that the rubberized asphalt pavement mixes do achieve a reduction in measured noise. The paper will elaborate the use of testing protocol, measured noise results and the conclusions which will be of use by other municipalities in assessing the merits of using rubberized surface course asphalts to reduce noise in urban, noise-sensitive environments. CPATT has also started a laboratory program which involves the use of an impedance tube to test the sound absorption coefficient of the pavement in the laboratory. Preliminary results from the laboratory will be presented in addition to the field measurements. This study attempts to integrate laboratory and field test results to provide quiet pavement solutions.