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<br />- lanes. The following table establishes corner sight <br />distance for each design speed: <br />Design Speed {mph) Minimum Corner Intersection <br />Sight Distance, in Feet* <br />50 500 <br />40 400 <br />30 300 <br />20 200 <br />•Corner sight distance measured from a point on the minor road at least 15 <br />feet from the edge of the major road pavement and measured from a height of <br />eye to 3.75 feet on the minor road to a height of 4.5 feet on the major road. <br />See AASHTO Policy on Geometric Design of Rural Highways Figure VZII-5, Paqe <br />398. Intersections shall be designed with a 50-foot minimum corner radius of <br />pavement or surfacing. Where turning volumes are significant, consideration <br />shall be given to speed-change lanes and channelization. Intersection legs <br />operating under STOP control shall be designed at as close to right angles as <br />feasible. Intersections ehall be at plus or minus two percent a minimum of 20 <br />feet for each 10 miles per hour of design speed of the road, prior to the <br />intersection for arterial and collection. In mountainous terrain for Local <br />Access and Access Tracts, all grades shall flatten to 4 percent or less for at <br />least 50 feet approaching intersections and at least 25 feet from cul-de-sacs. <br />5-502 X. Side Slopes <br />Cut and fill slopes shall be required as shown in <br />.:".~ Figures 5-lA through 5-1F. In unstable soils, flatter <br />~.~;y- slopes may be required. Where heavy snowfall is <br />expected, flatter slopes in cuts on the southern side <br />of the roadway may be required to provide maximum sun <br />exposure. Flatter slopes shall be used wherever <br />possible to reduce erosion, to decrease maintenance <br />costs, to facilitate plant growth, and to provide for <br />safer operation. <br />Transition slopes shall be provided between adjoining <br />cuts and fills. Where cut or fill slopes intersect the <br />original ground surface, the cross-section shall be <br />rounded to blend the slope into the natural ground <br />surface. Any cut or fill slope steeper than 2:1 must <br />be supported by an engineering report certifying the <br />stability of the side slope. Any retaining structures <br />used to stabilize cut or fill sections must be designed <br />by a registered professional engineer. <br />Benching of side slopes shall be used sparingly and <br />only where justified by sound engineering reasons, such <br />as: <br />I. unstable material renders benching more <br />economical than flattening; <br />Page 5-5-15 <br />