NYSDOT's Highway Design Manual specifies 1 on 12 for curb going the other way, from flush to raised, mostly so snowplows would ride up it rather than slamming into it. This would also apply to the tires & bodywork of errant vehicles.
If pedestrians use the shoulder, use a 1 on 12 max grade to comply with ADA. Otherwise, I am not sure of any requirements other what's needed to provide drainage.
"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail." - Wm. Phelps Eno, ca. 1928
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