INTRODUCTION

The main theme of this report is the effectiveness of rubberized asphalt as a traffic noise mitigation measure. Locally collected noise information is supplemented with general noise test results from various locations, both nationally and internationally, where other jurisdictions are exploring the use of rubberized asphalt. However, this report does not attempt to reproduce the result of those other studies herein. The interested reader is encouraged to contact those entities or jurisdictions where other studies were performed for further information. This report is primarily meant to provide information on the studies conducted in Sacramento County.

In addition to the various noise test results, this report offers an overview of the factors that contribute to traffic noise generation. The report also contains the Sacramento County, State and Federal noise standards, which mandate the consideration of noise abatement measures in cases where traffic noise levels exceed acceptable limits. The noise standards are provided to illustrate the importance which is given to traffic noise impacts in Sacramento County, which in turn has led to substantial requirements for traffic noise abatement.

In recent years, Sacramento County has relied upon noise barriers as the primary noise mitigation option, and often times the only viable noise mitigation option, for various roadway improvement projects in the County. As a result, a substantial number of noise barriers have, and continue to be, constructed in cases where traffic noise is determined to be excessive. Concerns regarding the proliferation of noise barriers has resulted in the investigation of rubberized asphalt paving as a viable noise mitigation alternative. This investigation has been ongoing since the paving of Alta Arden Expressway with rubberized asphalt in October of 1993. This report summarizes the results of Sacramento County's ongoing investigation to date.