In a message dated 11/6/09 10:58:41 AM, email@example.com writes:
A 1/8" per foot slope is small and the camber and live load deflection might make that drainage slope insignificant.
I second that emotion, only changing "might" to "WILL." 1/8" is worthless; 1/4" *may* be adequate; my understanding is/was that the federal standard for their own projects was 1/2". Remember that the slope in a diagonal drain, as at a corner, is likely to be only half that of the main slope.