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

Observed efficiency
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Match line
Regression
UDFCD new
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Predicted efficiency
Figure 6-3: Type R curb inlet efficiency from all improved methods
6.3 Recommendations for Further Research
After examining the collected test data, and completing the analysis presented in this
report, the need for several types of additional data became apparent. For the on-grade
condition, use of the grate-only inlet configuration was done only for one inlet. In contrast, the
combination inlet was used in numbers ranging from one to three inlets. Because of this, the
body of test data for the grate-only inlet is incomplete when compared to the combination inlet.
By gathering more data for the grate-only inlet, and performing a similar analysis to the one
presented in this study, accurate methods could be developed for use of the Type 13 and 16
grates in varying numbers. As a minimum, the use of both Type 13 and 16 grates for two and
three inlets at the 2% longitudinal and 1% lateral slope configuration would provide considerable
insight. These slopes were the median of the ranges used in this study. At three depths per grate
this would require a total of twelve tests.
Characteristics of two inlets used in this study resulted in high efficiency. The Type 16
grate has directional vanes that capture frontal flow very well. Although the grate is placed in a
slight depression in the combination-inlet configuration, the depression is not as pronounced as
for the Type R inlet. The Type R curb inlet has a local depression, well below the gutter flow
line, that results in a high degree of capture of frontal and side flow. By combining these two
80