kall a slope=such & such % is old fashuned
Bak in 1800's, em bild rodes that wae...eezee tu du with primitiv equipment
It spozed tu meen the rise=x% av the horizontal distans (the run)
In praktis, em alwaes yuze the distans along the rode insted av the run
Reesunabel rodes limited tu bout 8%, so dont get much errer that wae
But 12.5% slope is rather big
run=4ft 8 inch =56 inch,
rise=12.5% av run =0.125*56=7 inch