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I I I I I I I I I I I I I I I I I I I Light-D.Ity Vehicles: Light-D.Ity Trucks: Motorcycles : Heavy-D..Ity Gas TIucks: Heavy-D.Ity Diesel Trucks: 80.3% 11. 6% 0.5% 4.5% 3.1% Percent OJldjHot starts: '!he percent of oold-start. vehicles was determined from the publication Determination of Percentaqes of Vehicles ~ting in the OJld start Mxie (Midurski, 'n1eodore P. am. Alan H. Gastaline. Environnenta1 Protectioo 1>qerv:::y, Office of Air t.UaJ.ity Planni.n:,) an:! st:.an:)ards. NI'IS PB-288 860 August 1977. 'Ihis sam::e gives typical oold start percentages by access time, time of day, ani general location (CBD, Frin:.Je, Expressway, etc. ) . In this case, cold-start percentages ~ d1csen for a1e-hour am. average eight-ha.1r con:litians for a friI'ge location. A one-minute additional access time was assumed, based on the relative level of traffic OOJ'geStioo in the area am the PrqJer interpretation of this level acx::ordi.rq to the previcus refe.reJ'lC:'e. '!he oold-start percentages are shown belCJW". Frirge lDcatioo OJld-start, Perc:entages: One-Hour - 35% Eight-Hour - 30% 3. Meteorological Can:titions Temperature: A temperature of 20 degrees Fahrenheit was used, reflectin;J the average t.e.rrperature }:)eb,1een December am. Janucuy, the ooldest nart:hs in this re;ion. Cartx>n mncxide emissions fram vehicles ten:i to be higher at lower TPI11fIF".ra'b.1res. wW Speed: A wirxl speed of 1.0 meter per se::::orrl was used as a worst case corrlition. '!his is the 10NeSt. speed at ~d1 the m:xiels will give calibrated results. law win:l speeds ten:i to reduce m:i.xi.rq, increasin:;J CD ~tians. ww Anjle: receptor. MixiIg Height: A mixing height of 1,000 meters was used which is a good estimate of average oon:litians in this area (see Guidelines for Air ()Jalitv Ma~ Plannim am Analysis Voltnne 9). '!he JOOSt critical wirrl argle was selected for each Pe.rs~ Factor: A meteorological persi.sterK:Je factor of 0.7 was used. '!his is the JOOSt conservative value in the ran:;}e suggested (0.6- 0.7) by the EPA. '!he persi.sterK:Je factor is awlied to one-hour 00 concentrations to obtain the equivalent average eight-hour CO concentrations. It attenpts to reflect the fact that worst case meteorological cxn:litions are oot likely to persist for a full eight- ha.1r period. 12