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0 Grade Reversals <br /> A grade reversal is just what it sounds like—a spot at which a climbing trail levels out and then changes <br /> direction, dropping subtly for 10 to 50 linear feet before rising again. This change in grade forces water to exit <br /> the trail at the low point of the grade reversal,before it can gain more volume, momentum, and erosive <br /> power. Grade reversals are known by several different terms, including grade dip,grade brake,drainage dip, <br /> and rolling dip. <br /> Frequent grade Grade Reversal ir'" Water may become <br /> reversals are a critical— 1),.., trapped on trail and <br /> and often overlooked— ���� flow long distances if <br /> there are no grade <br /> 1 element of sustainable , reversals. <br /> trail design.Most trails � ` <br /> will benefit from grade = \,,\ <br /> reversals every 20 to 50 �� <br /> feet, depending on soil <br /> type and rainfall. Bear this ,\ <br /> in mind:It's much easier ` <br /> to build a trail with grade <br /> reversals in it than to <br /> - A grade reversal <br /> come back a year later , forces water to 1 <br /> and try to retrofit them '.-44,,:w drain off the trail. <br /> into a poorly designed <br /> trail. For best results, dL <br /> ..0 le <br /> incorporate them in your <br /> design from the start! ,,, <br /> Grade reversals can <br /> help trails endure, even \ ,, <br /> with minimal mainte- +` <br /> nance.Older trails often i!°, \ <br /> have a deeply compacted, • N,,, <br /> concave trail tread that ,, <br /> collects water.With regu- � t •r <br /> tar grade reversals,this <br /> water will only be trapped <br /> on the trail for a short distance before it can drain. Grade reversals effectively divide the trail into short, indi- <br /> vidual watersheds, so the drainage characteristics of one section of trail won't affect any other section. <br /> Grade reversals also make a trail more enjoyable. For mountain bikers, long runs of constant grade <br /> encourage excessive speed on a downhill and they're boring on an uphill. Short climbing interludes on a <br /> downhill provide variety, challenge,and let cyclists get off their brakes for a bit. Brief descents mixed into long <br /> climbs help all users regain their momentum and catch their breath. <br /> , <br /> 67 <br /> Part Three Principals of Sustainable Trails <br />