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Grades <br />Absolute Maximum: 10% <br />Avoid: 5% <br />for <br />lengths <br />greater than 300 feet <br />2% <br />for <br />lengths <br />greater than 1500 feet <br />Desirable: 5% <br />for <br />lengths <br />not greater than 100 feet <br />2% <br />for <br />lengths <br />not greater than 500 feet <br />Recommended grades for bikeways can be compared with Table 5, <br />Maximum Grades for Highways. A reduction in grade allows <br />an increase in the length of an inclined bikeway. Thus, <br />a 10% grade can be allowed only over very short sections, <br />However, the energy required to use a bikeway will affect <br />its usage and therefore grades should be kept at a minimum. <br />Methods to minimize grades are added curvature or increased <br />travel distance. Roadways which do not meet the grade <br />standards for bicycles should be avoided. <br />TABLE 5 <br />MAXIMUM GRADES FOR HIGHWAYS <br />Type of Terrain Design Speed MPH <br />20 30 40 50 60 <br />Flat 7 7 7 5 5 <br />Rolling 10 9 8 7 f <br />Mountainous 12 10 10 9 <br />Note: For highways with ADTs below 25 0 grades of <br />relatively short lengths may be increased to <br />150 per cent of the value shown. <br />Source: American Association of State Hiqhway Officials <br />-18 <br />