Hydraulic Efficiency of Grate and Curb Inlets - Urban Drainage and ...

design characteristics, higher efficiency would result than either is capable of independently.
The local depression would act to reduce splash-over and capture more side flow, while the
directional vanes would capture frontal flow. A full testing program similar to this study would
be required to develop design equations, or extend the UDFCD methods, for such an inlet.
Engineering application of the Type 13 grate inlet typically involves placing a single grate in a
sump condition with no curb component (such as in a parking lot or field). Placing a single Type
13 grate in such a configuration typically exposes it to direct flow from all sides. In the testing
program performed for this study, the inlet was placed adjacent to a curb and exposed to lateral
flow from three sides. Only at the 1-ft flow depth was it exposed to flow from over the curb.
Testing the Type 13 grate in a true sump condition, where it is exposed to flow from all sides,
would provide additional useful data. A slightly different model than the one used in this study
would be necessary to collect data on this configuration.
For the analysis presented in this report, the observed test data were used in UDFCD
methods developed from the original FHWA model data. The purpose was to adapt the UDFCD
methods to include the inlets tested in this study. The converse of that analysis would be to use
the FHWA model data in the empirical equations developed in this report. A comparison could
then be made between the two methods and their ability to be adapted to suit other inlet types.
The additional testing suggested in this section would complete the body of knowledge
available for common application of the Type 13, 16, and R inlets. The UDFCD methods could
be easily extended to encompass the additional data, and independent design equations similar to
those presented in this study could be developed for the additional configurations.
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