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<br />From: <br /> <br />Lon Aune, Assistant Public Works Director <br /> <br />..1% <br /> <br />To: <br /> <br />Mike Falk, City Planner <br /> <br />RE: DESIGN SPEED OF CURVE AT WESTERN AVENUE <br /> <br />Date: April 29, 1993 <br /> <br />At the April 12, 1993, Planning Commission meeting, a question <br />was raised by Commissioner Thomas concerning the curve design at <br />Western Avenue and OWasso Boulevard. Although the curve is <br />posted for 25 mph, it was constructed at the 30 mph design. In <br />designing the curve two main criteria were taken into <br />consideration: <br /> <br />1. Sight-stopping distance <br />2. Radius of the curve. <br /> <br />These standards can be found in the Road Design Manual, Part 1 <br />from the Minnesota Department of Transportation. <br /> <br />According to this manual, a 30 mph curve must have a minimum <br />sight-stopping distance of 200 feet. This means that a driver <br />noticing an object should be able to react and brake to a stop <br />within 200 feet from the moment the object was noticed. The 200- <br />foot sight distance can be maintained within the right-of-way for <br />any point on the Western Avenue curve. As recommended in Case <br />File 2466, the placing of a 10-foot easement to prohibit any <br />obstruction to visibility would provide sight-stopping distance <br />of approximately 250 feet. <br /> <br />The second reviewed in the designing of curves is the radius of <br />the curve. For a 30 mph curve, the minimum radius is 215 feet. <br />The radius on the Western Avenue curve is approximately 270 feet <br />which is well in excess of the required minimum. <br /> <br />The evaluation of the Western Avenue curve finds that the curve <br />meets the 30 mph design criteria. <br />