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. |
Curb# | This must reference a "Curb" line, in which the inlet is placed. |
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. |
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. |
Sw' | Slope measured from the pavement cross-slope, including gutter depression and any added depression at the inlet |
Se | see below |
Lt | The required length of curb opening for total interception of curb flow. |
E | The inlet efficiency, or portion of curb flow intercepted, given as a fraction of 1. |
Qb | The carryover flow, or flow which is not captured, in cases where E is less than 1. |
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.
Se = Sx + S'w Eo
Lt = 0.6 Q0.42 S0.3 (1/nSe)0.6 (0.6 is 0.076 in metric)
E = 1 - (1 - L/Lt)1.8
(return)