I have a question about what the gutter width definition is compared to the grate width. Are they the same thing? The gutter width I am referring to here can be found in the 'Add/Edit Dialog' window under "Gutter Details".
If there is a catch basin (grate of 2 ft. by 2 ft.) along a highway on the shoulder that is 10 ft. wide, what is considered to be the "gutter width"? Is it 2 ft. or 10 ft.? Say the 10 ft. shoulder has a slope of 3% and the roadway has a slope of 2%, what should the gutter width be?
Also, what should be entered as Sx (Road Cross Slope) if the crown of the road splits off at the edge where the shoulder and road meets? Should the 2% Road slope be considered in this case even if it does not pitch towards the catch basin?
in your case, i would use the gutter width as the width of the inlet grate (2 ft), and use the 3% as the gutter and road cross slope (treating the rest of the shoulder as the travel lane). if your gutter spread is more than the width of the shoulder (past the high point), then i would make it a double inlet. hope this helps.