Agenda - Council - 05/28/2002 - Laserfiche WebLink

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Mr. Steve 3'anko wski ~[r. B~]an Otson April 29, 2002 Page 2 Noise modeling was done ,~smg the noise prediction pro_re'am "NED, I'NO[SE", a version of ti:to FHWA %T,~¥[.hNA" model adapted by NLWDOT. Tins model uses vehicle numbers, 'speed, class o~' vehicle, and topographical characteristics or' the roadway and receptors being analyzed. SRF used the grading ptans produced by tim developers' architects (these plans are the basis for the attached figures) to determine the elevauons of the receptors wit. bin the devetgpmenr. Modeling performed for this analysis assumed a peak hour traffic volume o£ 2,.500 veh/cles, o£ wh/ch 9'7 percent are automobiles and light truc~, ea~o percent are medium u-ucl~, and one percent heavy a-acks. This tra~hc volume was used as a "worst-case" scenario to approx/rnaze daytime peak n-affic noise levels a.long TH 47 after de construction of the development. Posted speed limits were used m the noise model. Analyzed Noise Miti=ation To assess de effectiveness of noise mitigation for dis development, noise barriers of ~o Izeig/ats (6 and 10 feet) were modeled along ~he eastern boundary of the cievelopmenrS (see attached figures). For Mae 2nd Addition analysis, the barrier extends along the eastern proper7? boundar-/ Wtth a break ar the TH 47/~.56d Lane intersection and stops appro×/.mateiy 600 ~'eet sou~ of 156d Lane. Two locations tbr noise burners were modeled for ttze 3rd Addition: wes~ of TH 47 along rlxe highway ngtx-of-wa7, and west of de wetland. Toe modeled barrier, represents a solid fence or a berm, or a combination of the two. The {zeigtx of the studied noise barners was limited to ten feet due ro aes~etic, engineering and cost concerns. T'ae rotations of potential noise barriers were limited ~o witb. m the boundaries of the developments except dot a potential barrier was modeled along Mae lzig/away ri~t of way for the 3''~ Addition. While barriers of ten feet in heig/zt are e~"ective m mitigating tire noise (t/re/road contact noise dominates traffic noise from cars and [i~*-hzt trucks), Maey are not as effective ar reducing rmck noise, which is dominated by en~ne and exhaust noise that or/g/nato ar heights several fe:: above the road surface. Results of Noise Anal,/sis Tlae results of the noise analysis are presented in Mae following tat~les. Results are presented as Lt0 A-weighted decibels (dBA). T'ae Lt0 descr/ptor indicates Maat the noise levels represent ~e noise level that is exceeded tar rbe loudest ten percent of a t/me period, ar the loudest six minutes of an hour. "A" weighting ap'proximares Mae way that an average person bears sounds. 7/ildli,/k Sancxuary gad Addition Noise [evets ar the 2nd Addition of the Wildlife Sanctuary will exceed state dayrlme noise standards at the tbur first row homes by up ~o ~bur dBA. A six-foot-high barrier would reduce tra~hc noise by zero ro three dBA and provide a noticeable decrease (three dBA) at only ~,a,o residences. A ten-tbot-~Ugh burner would provide a zero to five dBA reduction and provide a not~ceat01e decrease at only cwo residences. -101-