Appendix A Noise Study Report - Laserfiche WebLink

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Chapter 5. Study Methods and Procedures 5.2.1. Short -Term Measurements Short-term noise level measurements in the project vicinity were sampled during off-peak traffic hours when traffic was flowing freely. Short-term noise level measurements were made using Larson Davis Model 831, 824, and 820 Type 1 sound level meters. The following measurement procedures were used: • Calibrate the sound level meter. • Set up the sound level meter at a height of 5 ft. • Commence noise monitoring. • Collect site -specific data (e.g., date, time, direction of traffic, vehicle speed, and location of the sound level meter relative to any existing feature). • Count passing vehicles for a period of 20 minutes during noise level measurement. Vehicles are split into three categories: automobiles, medium trucks, and heavy trucks. • Stop measurement after 20 minutes. • Calibrate the sound level meter. • Proceed to the next monitoring site and repeat. The traffic counts were expanded to hourly volumes (multiplied by three to normalize the results to hourly values) and entered into the FHWA Traffic Noise Model (TNM) 2.5 (2004) for each monitoring site. The monitoring results were used to calibrate the model outputs. 5.2.2. Long -Term Measurements Two long-term noise level measurements were conducted using one dosimeter in the study area. The purpose of the long-term measurements was to identify variations in sound levels throughout the day. 5.3. Traffic Noise Level Prediction Methods Traffic noise levels were predicted using the FHWA's TNM 2.5 (FHWA 2004). TNM 2.5 is a computer model based on two FHWA reports: FHWA-PD-96-009 and FHWA PD-96-010 (FHWA 1998a, 1998b). Key inputs to TNM 2.5 were the locations of roadways, traffic mix, vehicle speeds, shielding features (e.g., topography and buildings), noise barriers, ground type, and receptors. Fairview Street Improvements from 9th Street to 16th Street 27 and Bridge Replacement Project Noise Study Report