Laserfiche WebLink
<br /> --., ~ .--,..- <br /> I " <br /> - <br /> ~ <br /> I. _1 ' <br /> - <br /> Chart I illustrates how noise levels vary with distance from the source. As noted above, traffic noise -~ <br /> I dissipates at a rate of 3 dBA per doubling of distance from the Source, In addition, ground and atmospheric "" <br /> absorption results in an additional 1_5 dBA reduction per doubling of distance from the source. .... <br /> _c_ <br /> I Chart 2 shows the variation of noise levels with vehicle operating speed. A volume of traffic passing a point ;;.:n <br /> at fifty MPH would generate approximately 75 dBA. The same volume of traffic at 30 MPH would generate <br /> approximately 70 dBA. - <br /> I Chart 3 shows the relationship between noise levels and traffic volumes, As described earlier, a doubling _tL_ <br /> of the sound energy results in a 3 dBA increase in noise levels. Therefore, traffic volumes must double to - <br /> cause a 3 dBA increase in traffic noise levels, <br /> I =--- <br /> Chart 4 documents the relationship between noise levels and truck percentage, Trucks are a significant noise <br /> --'- <br /> source and the percentage oftrucks in the vehicle mix is an important determinant of noise levels, <br /> I :",.-11 <br /> NOISE STANDARDS AND MITIGATION CRITERIA - <br /> I State of Minnesota noise standards (Minnesota Rules Parts 7030.0010 to 7030.0080) specify noise level _11 <br /> limits for various land use classifications, The table on page 6 documents the state noise standards for both <br /> daytime (7:00 a.m, to ]0:00 p.m.) and nighttime (10:00 p.m. to 7:00 a.m,) conditions, The standards are <br /> I considered to be consistent with speech, sleep, annoyance and hearing conversation requirements in each ..." <br /> land use classification and are applied in exterior areas, - <br /> ~,~. <br /> I- The standards for Noise Area Classification (NAC-l) apply to residential areas and other uses intended for ioill.----,-- <br /> overnight sleeping (hotels, motels, mobile homes, etc.), The NAC- I standards also apply to schools, <br /> churches, medical services, and park areas, The nighttime standards are only applicable in areas intended <br /> I for ovemight sleeping. The NAC-I daytime standards apply during nighttimeh'ours at other NAC,] uses _i_~ <br /> not intended for overnight sleeping, - <br /> I IIi:Jl!. <br /> I iIIiiJi <br /> - <br /> I __c__ <br /> . <br /> I ""'- <br /> - <br /> I ... <br /> I ... <br /> - <br /> I- - <br /> ... <br /> . - <br /> .' <br /> I 44 ... <br /> - <br />