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2008 Base Conditions <br />Finally, the "calibrated" model is verified against the base-year traffic counts. The <br />verification process is a series of post-simulation run analyses that are designed <br />to analyze the accuracy and degree of confidence presented in the calibrated <br />results. Included in these analyses are verification of the trip distribution <br />characteristics and comparisons of the traffic count data vs. modeled link <br />volumes. These are typically analyzed with screenlines and scattergrams. <br />Screenlines <br />Nine (9) Screenlines were established showing major movements within the <br />County. These were chosen at locations were counts were also available. The <br />screenlines were summarized and analyzed for trends and acceptability. These <br />are shown in Figure 5. <br />. .......... {~]. ...................... · ......... .. <br />~I <br />.J <br />Figure 5 <br />Kittitas County Screenline Locations <br />!f I <br />NCHRP 255 establishes standards for allowable deviation based upon traffic <br />count volumes. Lower volume screenlines are allowed more deviation because <br />of the increased amount of variation in count data and the lesser importance of <br />Kittita s County, Washington Trans p o rtation Model -May 2009 Page 40