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applied throughout the nation was used to evaluate current noise <br />conditions at various points along Bristol Street within the Area <br />of Potential Environmental Impact (APEI). This model accepts <br />various parameters including: the traffic volume; vehicle mix and <br />speed; and roadway geometry in computing equivalent noise levels <br />during typical daytime, evening, and nighttime hours. <br />The resultant noise levels can then be weighted, summed over 24 <br />hours, and output as the CNEL value. Various CNEL contours are <br />subsequently located through a series of computerized iterations <br />designed to isolate the critical contour locations. Noise <br />contours were developed as a planning tool for local agencies. <br />Tables 4 -5 and 4 -6 provide the predicted current CNEL and Leq <br />levels adjacent to Bristol Street in the APEI. Assuming a noise <br />reduction with distance factor of 3.0 dBA with each doubling, and <br />assuming no adjustment for local attenuation (houses, buildings, <br />noise barriers, etc.) the distance to various noise contours used <br />for land use compatibility purposes have also been determined and <br />shown. <br />TABLE 4 -5 <br />CURRENT EXTERIOR CNEL EXPOSURE <br />ADJACENT TO BRISTOL STREET <br />Roadway Link^ r -- ^~ <br />TCurrent <br />r <br />CNEL a <br />Dist. to <br />Contour -(ft)2 <br />(Speed) <br />A.D.T.1 <br />75 ft. <br />70 dBA 65 <br />dBA 60 dBA <br />Bristol Street (35,40 mph) <br />-NIO <br />Warner Avenue <br />33,400 <br />70 <br />78 <br />232 <br />729 <br />-N 10 <br />Edinger Avenue <br />31,900 <br />69 <br />57 <br />161 <br />502 <br />-N10 <br />McFadden Avenue <br />35,700 <br />69 <br />62 <br />179 <br />562 <br />-N10 <br />Bishop Street <br />40,000 <br />70 <br />68 <br />201 <br />630 <br />-N /O <br />First Street <br />35,500 <br />69 <br />62 <br />178 <br />559 <br />-N10 <br />Santa Ana Blvd. <br />35,500 <br />69 <br />62 <br />178 <br />559 <br />-N/0 <br />Fifth Street <br />36,700 <br />69 <br />61 <br />183 <br />577 <br />-N10 <br />Civic Center Drive <br />37,300 <br />69 <br />62 <br />186 <br />587 <br />-NIO <br />Washington Street <br />39,400 <br />70 <br />68 <br />198 <br />620 <br />-N10 <br />Seventeenth Street <br />42,800 <br />71 <br />95 <br />296 <br />934 <br />-NIO <br />Santa Clara Avenue <br />48,600 <br />72 <br />110 <br />336 <br />1060 <br />1. <br />A.D.T. means 1987 <br />average daily two -way traffic <br />volume. <br />2. <br />All distances are <br />measured <br />from the <br />centerline. <br />All contours <br />ignore localized shielding <br />effects. <br />The FHWA RD- 707 -108 noise model predicts noise levels based upon <br />average traffic volumes, speeds, roadway width, truck mix, and <br />distance to observers. Noise measurements reflect the actual <br />r Conditions on one particular day at the location monitored. <br />4 -11 <br />