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<br />5.0 Noise Analysis Conclusion and Summary <br /> <br />Traffic noise impacts occur when traffic noise levels approach or exceed the FHW A NAC-l <br />(70dBA) level by one decibel or when impacts are modeled exceeding state noise standards, <br />or those for which the project increase the existing levels by more than 5 dBA. <br /> <br />Impacts were registered at 20 virtual (MINNOISE) receptors. 10 of these receptors also <br />registered levels approaching and exceeding FHW A guidelines (PM 2030). <br /> <br />A mitigation analysis was performed to gauge the effectiveness of 20' and 10' noise barriers <br />placed to shield receptors I-J on the north side of Round Lake. This noise barrier, or "RL <br />Noise Barrier 1", revealed that noise barriers are not cost effective or economically feasible. <br />Further; "Noise Barrier 2" and "Noise Barrier 2ext" along the east shore of Round Lake are <br />not cost effective or economically feasible and therefore should not be considered for design <br />and construction in this configuration. <br /> <br />And finally, those receptors (K-M) which are shielded by a new noise barrier north of Briar <br />Knoll Drive and on the east side of Highway 10 did not receive a substantial noise <br />attenuation benefit greater than 5dBA with a 10' noise batTier. <br /> <br />However, a 20' noise barrier at this location does create acoustic benefits greater than 5dBA <br />at three residences (receptors Land M). However, there are not enough protected residences <br />at this location to meet the MnDOT cost per decibel reduction of $3,250 and is therefore not <br />cost effective. <br /> <br />I Mn/DOT Noise Policy for Type I and Type II Federal-aid Projects as per 23 eFR 772 <br />Authority: 23 U.S.c. 109(h), J 09(1): 42 U.S.c. 4331,4332; and 49 CFR 1,48(b). <br /> <br />Noise Barrier Analysis <br />Highway 10 <br /> <br />Page 11 <br />