DOT specifications call for a transverse slope of roughly one to three inches of drop per five feet of width, and a flag that doesn't drain toward the curb, that retains water, or that exceeds this range can itself be cited as a substantial defect under Administrative Code § 19-152. Getting this pitch right is one of the more common failure points in amateur or non-compliant repairs, since a flag can look perfectly flat and still fail inspection if its slope is off. Proper transverse slope also matters for ADA accessibility, since excessive cross slope makes a route harder to navigate for wheelchair users.
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