Originally Posted by
KevinF
It is usually calculated with the run being the length of the road, simply to make the math a little easier. For the angles on any sort of "normal" road though -- it simply doesn't make any signifigant difference to the final answer.
I was under the impression that percent grade was synonymous with gradient not just conveniently close around 0 which means that it would be calculated that way and the rise/run method would be the convienent approximation.