Laserfiche WebLink
<br />NAC. In this instance, levels predicted as 69dBA are considered approaching the <br />FHW A NAC of 70dBA. <br /> <br />If one or more of the above conditions are met, noise barriers need to be considered based <br />upon cost reasonableness and noise barrier feasibility. <br /> <br />"Cost reasonableness" defines a ratio of cost per square foot to effectiveness of attenuation. <br />This is detennined by dividing the total cost of a barrier (Mn/DOT currently uses $15 per <br />square foot) by the total decibel reduction for residences that are predicted to have a >5dBA <br />reduction in noise. A "reasonable" cost is defined as equal to or less than <br />$3250/dBA/residence. "Feasibility" is defined as whether a noise barrier may be built <br />considering proper setback, sight lines, and location. <br /> <br />3 separate 20 and 10 foot high noise barriers (Mn/DOT maximum) were placed within the <br />MINNOISE model to gauge effectiveness during that of the "daytime" or PM time frame. <br />These noise barriers are located between Highway 10 and the access road to the homes on the <br />east shore of Round Lake. For the purposes of this report, the noise barrier at the north end <br />of Round Lake will be labeled "RL Noise Barrier 1 ", the noise barrier at the midway point <br />"RL Noise Barrier 2", and a south em extension to "RL Noise Barrier 2" labeled "RL Noise <br />Barrier 2ext". <br /> <br />3.1 Round Lake Noise Barrier 1 <br /> <br />Figure 4 and 5 illustrate the complete noise impact survey including design year levels <br />(2030), MINNOISE modeled noise figures, resulting differences and noise barrier attenuation <br />figures for both a 20' and 10' barrier at the "RL Noise Barrier I" location. This location <br />shields 5 homes (Receptors I and J) in the southwest quadrant ofHwy 96 and 10 and is 870' <br />long. <br /> <br /> <br />Total Length of <br />Barrier :870' <br /> <br />Total Attenuation <br />Cost of 20' Barrier (@$15/sq.ft)=$261.000/44.7 decibel reduction <br /> <br />55,839 <br /> <br />Figure 4. 20' Noise Barrier Feasibility Table, RL Noise Barrier I. <br /> <br />Noise Barrier Analysis <br />Highway 10 <br /> <br />Page 5 <br />