Burien Town Square Street Improvements Noise Assessment

(Burien, WA)  Burien Town Square provides for the reestablishment of a local and collector arterial street system within the downtown core of Burien, and includes a roundabout and added intersections. Landau Associates performed an air quality impact assessment for the proposed improvements to the study area. The study area was within an Environmental Protection Agency Air Quality Maintenance Area. In order to determine if the potential development would comply with Clean Air Act standards, a “hot spot” analysis of the worst-performing intersections in the study area was performed. Landau Associates evaluated the primary air pollutants associated with transportation projects, including carbon monoxide (CO), particulate matter (PM10 and PM2.5), and ozone. The vehicular CO emission rates were calculated using the model MOBILE6.2, based upon data describing the local vehicle fleet and driving conditions. Ambient CO concentrations near the roadway at the worst-performing intersections were estimated for existing conditions, the initial year of project operation, and the project design year of 2030 using the model CAL3QHC, which incorporates MOBILE6.2 model results. The collected data and analysis demonstrating conformity with the Clean Air Act was presented in an Air Quality Discipline Report and submitted to Washington State Department of Transportation (WSDOT).

Based on a field reconnaissance and review of the Burien Town Square development plans, Landau Associates identified noise measurement locations to best characterize the existing noise environment. After collecting onsite noise level measurements, Landau Associates used that data along with traffic flow information to evaluate current noise levels using the Federal Highway Administration (FHWA) Traffic Noise Model. Using the FHWA model to project post-development noise impacts, Landau Associates determined that the project impacts would comply with FHWA and WSDOT requirements. The noise study supported the conclusion that noise abatement would not be required.