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Appendix G | 3 <br /> <br />account for seasonal variation, data was collected in October to represent non-snow conditions and <br />in February to reflect ski-season traffic. <br />Turning movement counts for non-snow conditions were collected on Thursday, October 17th, 2024, <br />from 3 PM to 6PM, and on Saturday, October 19th, 2024, from 12 PM to 4 PM. Counts for snowy <br />conditions were collected on Friday, February 14th, 2025, and Saturday, February 15th, 2025, from 11 <br />AM to 3 PM on both days. These time windows were selected based on observed peak travel periods <br />in the area. At each intersection, the peak hour was identified as the four consecutive 15-minute <br />intervals with the highest combined turning movement volumes during the count period. <br />LOS was analyzed for all study intersections under four scenarios: weekday and weekend conditions <br />in both October and February. All intersections were unsignalized (stop-controlled) and evaluated <br />using Synchro 12 software, following methodologies from the Highway Capacity Manual (HCM) 7th <br />Edition. Each scenario was analyzed under existing conditions and a 20-year forecast scenario. <br />Study Intersections: <br />• SR 906 & I-90 EB Off-Ramp <br />• SR 906 & Guye Peak Lane 4 <br />• I-90 WB Off-Ramp/I-90 WB On-Ramp & Yellowstone Trail Rd <br />• SR 906 & Tanner Way/Driveway <br />• Hyak Dr E & SR 906 & Driveway <br />• SR 906 & I-90 EB Off-Ramp/I-90 EB On-Ramp <br />• SR 906 & I-90 WB Ramp <br />For the forecast analysis, a 27% growth rate was applied to the observed counts to estimate future <br />traffic volumes. This growth rate reflects countywide population projections from the Washington <br />State Office of Financial Management (OFM) for Kittitas County and is consistent with projected <br />traffic increases on I-90, the sole access route to Snoqualmie Pass. The methodology and growth <br />assumption were confirmed by Kittitas County staff. <br />Results <br />The tables below show peak hour LOS results for the studied intersections on weekdays and <br />weekends in both October and February. Table 2 shows results for existing conditions, and Table 3 <br />shows results for future conditions. The results show that, in general, weekdays experience less delay <br />than weekends, and February conditions result in more delay than those in October. Despite these <br />variations, all intersections under both existing and future forecasted conditions remain within <br />WSDOT’s acceptable LOS standards. <br /> <br />4 During the February data collection period, the camera equipment was knocked over. Volumes for the NBR, <br />SBL, and WBR movements were estimated based on counts at adjacent intersections and counts collected in <br />October.