name | Text of up to 10 characters. Blanks are not allowed. This is in order to preserve the tabular printout, which can be read back into the program. |
Curb1# | This must reference a "Curb" line, in which the inlet is placed. |
Curb2# | This must reference a "Curb" line, in which the inlet is placed. This would be the opposing side of the inlet in a sag. If there is no opposing side, and only one curb section and flow is to be referenced, use the same reference as Curb1#. |
L | Length of the curb opening along the curb. |
loc.depr. | Local depression at the inlet mouth. It is in addition to any depression of the gutter associated with W and Sw for the curb section. The width of this local depression is assumed to be the same as the gutter, or W dimension given for the curb. |
h | Height of the inlet opening, measured perpendicular to the angle. |
angle | Angle of the inlet opening. |
d | Depth of flow at the inlet, measured from where the pavement cross-slope (Sx) meets the curb. |
di | Depth of flow at the inlet, measured from the inlet lip; (for weir flow: d+a) (for orifice flow; d+h*sin[angle]). |
al | Local depression, not actually computed output. |
a | This is the local depression added to the gutter depression associated with W and Sw given for the curb. It is measured from where the line along Sx from the lane would intersect the curb. (12*W*(Sw-Sx)+al) |
T | Width of spread at the inlet. This will be computed from both referenced curbs, and the wider spread given. The flow is the sum of the curb flows. |
The formulas and nomenclature of the Federal Highway Administration's Hydraulic Engineering Circular No. 12 (HEC-12) are used, with further clarification in Hydraulic Engineering Circular No.22 (HEC-22). The referenced formulas are listed below. The default dimensions use a standard VDOT drop inlet.
Qweir = 2.3 (L + 1.8w) d1.5 (for d < h + a) ( 2.3 is 1.25 in metric) (d is measured from the pavement cross slope intersection)
Qorifice = 0.67 h L (2 g do)0.5 (for d > 1.4h) (do is measured to the center of orifice, d(from lip) - (h/2)sin(angle))
(return)