This report examines five special noise barrier applications that exist in addition to the conventional vertical reflective barrier. The acoustic, aesthetic, and economic feasibility of absorptive T-top, Y-top, slanted-top, single-wall absorptive, and absorptive parallel noise barriers are addressed as they compare to a conventional noise barrier.
The primary objective of this research was to test these five applications analytically on several actual highway projects to gain definitive information on their real potential. Four WSDOT highway noise mitigation projects were selected for use as field laboratories for examining the application potential of the special barrier treatments. Three of these highway projects are located in Seattle: Fourth Avenue S.E and Magnolia Road, both located on SR-405 in King Co. and in South Snohomish Co.; and Kent Commons Play Field, located on SR-167. The other project is the Spokane Community College Area, located on the Market/Greene alternative of the planned North Spokane Freeway route