When runoff exceeds inlet capacity, the spread, depth and velocity of ponded water may be calculated from the geometry and hydraulic properties of the cross section.
In an XPSWMM/XPStorm model, Pavement Crossfalls may be stored in the Global Database. A Pavement Crossfall record is assigned to a hydraulics inlet node using the Inlet Capacity dialog.
As shown in the above diagram, the Pavement Crossfalls are defined as a section extending from the boundary line (representing the edge of the drainage) to the pavement centerline. It consists of three regions:
- Verge (Shoulder) region between the boundary and the gutter
- Gutter channel draining to drainage inlet, lowest point designated as invert
- Pavement roadway surface extending from the lip to the centerline (or highpoint)
The terms in the dialog are defined as:
A Verge (Shoulder) Distance (Boundary to Back of Curb) (ft, m)
B Verge (Shoulder) Slope (Boundary to Back of Curb) (%)
n-verge Verge (Shoulder) Roughness (Manning's n)
C Width of Top of Back of Curb (ft, m)
D Distance from Face of Curb to Nominal Curb Line
E Distance from Nominal Curb Line to Gutter Invert (ft, m)
F Distance from Gutter Invert to Curb Lip (ft, m)
G Depth from Back of Curb to Gutter Invert (ft, m)
H Depth from Back of Curb to Gutter/Pavement Lip (ft, m)
n-gutter Gutter Roughness n
I Pavement Width (Lip to Road Centerline) (ft, m)
J Pavement Crossfall (Lip to Road Centerline) (%)
n-pave Pavement Roughness n
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