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On September 25, 2020 Public Works (PW) received a request to study Thrall Road speeds between <br />No. 6 Road and Moe Road (Milepoints 0.05 and 1.10) and to lower the speed limit from 50 miles per <br />hour to 35 miles per hour (EXHIBIT 1). Responding to the request, PW set speed counters out for a <br />one-week period (10/01 — 10/08/2020). Speed study results are provided as EXHIBIT 2. In addition <br />to collecting speed data, PW dispatched our staff to evaluate vertical and horizontal curves in the road <br />segment for conformance to national design standards. The petition cites increased residential <br />development and agricultural use for the increased traffic volume, also the concern of crashes as being <br />the reasons for speed concern. <br />DISCUSSION: <br />The segment of Thrall Road between No. 6 Road and Moe Road includes two horizontal curves. <br />Public Works' evaluation of roadway geometrics (horizontal and vertical curves) affirms appropriate <br />design conformance to national standards of engineering practice (50 MPH design speed) for the <br />western curve. The radius and cross slope combination on the eastern curve match the design criteria <br />for a 45 mph curve. The crash reports did not indicate the curve geometry to have been a factor. 85' <br />percentile speeds in both directions (east and west) are higher than current posted 50 MPH speed limit, <br />indicating driver comfort with existing road conditions. Since 2015 there have been nine recorded <br />vehicle crashes in this road section, with the majority occurring in 2017 and 2018. Of the nine none <br />were cited for driving over the posted speed limit. Four were related to snow and ice conditions. One <br />was related to an insecure load and one related to a deer impact. The three remaining were related to <br />distracted driving. Crash data does not correlate to the posted speed. There are five approaches within <br />this section of roadway. Thrall Road is similar to many county roads, narrow lanes with a minimal <br />shoulder. Urbanization and increased agriculture activity have resulted in higher traffic volumes. <br />Thrall Road is operating within the Level of Service standard for rural road operations. Our most <br />recent twenty-year transportation plan does not forecast Thrall Road as breaking accepted levels of <br />service in the next twenty years. <br />FISCAL IMPACTS: <br />Posting the new 35 MPH speed signs is expected to cost in the range of $2,000. Public Works <br />budgets for this activity annually in our road maintenance budget. <br />ATTACHMENTS: <br />EXHIBIT l: Request for speed reduction <br />EXHIBIT 2: Speed study results <br />Page 2 of 4 <br />PUBLIC WORKS BOARD OF COUNTY COMMISSIONERS ENGINEER'S REPORT <br />