## Curb Opening Hydraulics Calculator

The curb opening calculation is a program that will calculate the capacity of a curb opening on grade conditions, and will determine the length to capture a percentage of flow. This calculation is not to be used in conjunction with the modified Manning calculations for inlet grates.

## Instructions

Enter 4 of the 5 variables and the remaining variable will be calculated.

The normal variables typically entered are Longitudinal **(S**_{L}) and Transverse **(S**_{T}) slopes, Manning roughness coefficient **n:** and either but not both the curb opening length **(L**_{T}) or the flow **(Q)**.

**If an efficiency number from 0 to 1 is entered it will determine the length of a curb opening that will capture that fraction of flow.**

**The efficiency of curb-opening inlets shorter than the length required for total interception is expressed by the **

following equation:

**A modified version of the first equation that deals with gutter depression and curb opening efficiency.**