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<br />John Stark, Community Development Director <br />City ofRoseville <br /> <br />November 17,2006 <br />Page 20 <br /> <br />Carbon Monoxide Modeling Results <br /> <br />Future CO concentrations are analyzed based on forecast peak hour traffic volumes, optimized <br />signal timing, and existing intersection geometries. Analyses were performed for the year 2030. <br /> <br />The sidewalk averaging techniqne was lIsed to predict the average CO concentration along each <br />sidewalk adjacent to the analyzed intersections. In this method, receptors are placed parallel to <br />each leg of the intersection along each sidewalk at 10 meters and 50 meters from the intersection. <br />The average concentration of the two receptors is considered the concentration for that sidewalk. <br />The listed result shows the maximum ofthe eight sidewalks adjacent to the intersection. <br /> <br />Table 6 presents the worst-case CO concentrations at the modeled intersections. The wind <br />direction column indicates the wind direction that resulted in the worst-case conditions for that <br />analysis location and time. The I-hour and 8-hour average modeling results are below the state <br />standards for all conditions modeled. <br /> <br />Table 6 <br />Future Modeled Carbon Monoxide Concentrations <br />(in parts per million or ppm) <br /> <br /> I-Hollr Average 8-Hour Average Wiud Direction <br />County Road Cat Fairview Avenue <br />Modeled CO Concentration 1.7 1.2 <br />Background CO Concentration 5.4 3.6 <br />Total Predicted CO Concentration 7.1 4.8 80 <br />County Road C at Snelling Avenue <br />Modeled CO Concentration 2.1 1.5 <br />Background CO Concentration 5.4 3.6 <br />Total Predicted CO Concentration 7.5 5.1 190 <br />State Standards 30.0 9.0 <br /> <br />Predicted CO concentrations at the analyzed intersections will be below state standards after <br />completion of the project in year 2030. Because these intersections are the two worst case <br />intersections in terms oflevel of service and total delay, CO concentrations at other intersections <br />in the study area would likely be lower than those predicted at the analyzed intersections. <br /> <br />VEHICLE-RELATED NOISE ANALYSIS <br /> <br />The purpose of the vehicle-related noise analysis is to determine the comparable noise impacts <br />from existing year 2006 conditions to year 2030 build conditions. Previous AUAR analyses in <br />the Twin Lakes area was conducted for year 2001 conditions compared to year 2020 build <br />conditions. This updated analysis will determine the potential increase from the previous <br />analysis. Three residential areas adjacent to the Twin Lakes AUAR were considered for this <br />analysis: <br />