COMPLIANCE INFO_FINAL INITIAL STUDY/MITIGATED NEGATIVE DECLARATION 5/25

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Mr. Rob Carnachan Page 12 March 6, 2025 in the vicinity of the North County Landfill during the November 2024 counts, the 85th percentile (or “critical”) speed was measured as 66 mph, which was rounded up to 70 mph for the purpose of this analysis. The HDM lists the design vehicle to use for rural intersections as the “passenger car.” However, the more conservative “single- unit truck” design vehicle was selected given the prevalence of truck traffic using the site. With a 70-mph design speed and single-unit-truck design vehicle, corner sight distances for motorists on the driveway approach of 980 feet to the left and 875 feet to the right are required. For drivers turning into the site from the road, a stopping sight distance of 750 is prescribed. During a field visit conducted in January 2025, sight lines were established to be in excess of 1,000 feet in all directions. Finding – There is sufficient sight distance in all directions at the existing site driveway on East Harney Lane, resulting in a less-than-significant impact of the project on safety via sight distance. Turn Lane Warrants The need for a left-turn lane on East Harney Lane was evaluated based on criteria contained in the Intersection Channelization Design Guide, National Cooperative Highway Research Program (NCHRP) Report No. 279, Transportation Research Board, 1985, as well as an update of the methodology developed by the Washington State Department of Transportation and published in the Method For Prioritizing Intersection Improvements, 1997. The NCHRP report references a methodology developed by M. D. Harmelink that includes equations that can be applied to expected or actual traffic volumes to determine the need for a left-turn pocket based on safety issues. Under future volumes with the addition of traffic associated with the project to the a.m. peak hour, a left-turn lane into the project site from East Harney Lane would not be warranted. As all other scenarios have lower traffic volumes, by inspection a left-turn lane would not be warranted under these other scenarios as well. The worksheet for the turn lane warrant assessment is enclosed. Finding – A left-turn lane into the project site would not be warranted under any volume scenario assessed, so the project would have a less-than-significant impact on the safety of site access. Queuing Under each scenario, the projected maximum queues approaching each intersection along with the maximum queues estimated for the two left-turn pockets at East Harney Lane/SR-88 were determined using the SIMTRAFFIC application of Synchro and averaging the maximum projected queue for each of ten runs. Summarized in Table 12 are the predicted queue lengths, for which copies of the SIMTRAFFIC projections are enclosed.