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3.2 Transportation <br />Demand <br />The transportation demand discussion includes <br />information regarding traffic conditions on 1-90 <br />and surrounding roadways. Also included below <br />is a discussion of other existing transportation <br />facilities in the study area. <br />3.2.1 Traffic Conditions <br />1-90 traffic conditions in the study area were <br />reviewed and modeled to determine peak <br />congestion times. These analyses took place in <br />2019 and 2023 and are discussed below. Modeling <br />and analysis focused on westbound traffic since <br />data indicate traffic is more dispersed in the <br />eastbound direction over various weekend days. <br />2019 Analysis <br />An analysis of 1-90 and county roads within <br />the Upper Kittitas County area was completed <br />in 2019 (Appendix A), specifically evaluating <br />how holiday traffic congestion on 1-90 impacts <br />the local road network. As part of this effort, <br />CHAPTER 3: EXISTING CONDITIONS IN THE STUDY AREA <br />several potential capital improvements <br />that might address traffic congestion issues <br />stemming from holiday traffic were modeled. <br />Holiday Congestion <br />Congestion along 1-90 is heaviest during summer <br />weekends and major holidays (Memorial Day, <br />4th of July, and Labor Day). In the westbound <br />direction, this regularly occurs between MP <br />70 and MP 93 on Sundays in summer, with <br />the most extreme congestion occurring on <br />the Mondays of Memorial Day and Labor Day <br />holiday weekends. Holiday traffic volumes are <br />approximately four times higher on 1-90 and <br />three times higher on county roads than typical <br />days. Speeds drop from an average of 70 mph to <br />15 mph on 1-90, and increase by approximately 5 <br />mph on county roads, reflecting that non -local <br />travelers tend to speed along the local roads <br />as they avoid 1-90 congestion. On those specific <br />Mondays, congestion lasts for 12 hours on <br />1-90, while diversion and increased speed lasts <br />approximately 6 hours on the county roads. <br />VOLUME 1: FEASIBILITY REPORT 1-90 Corridor - Easton to Cle Elum Feasibility Study 134 <br />