Difference between revisions of "Curb cuts"

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<math>R_c=1-\left ( 1-\frac{3}{9.71} \right )^{1.8}= 0.48</math>
<math>R_c=1-\left ( 1-\frac{3}{9.71} \right )^{1.8}= 0.48</math>


48% of the 0.08 m<sup>3</sup>/s flow would enter the bioretenteion cell through the inlet as designed.
48% of the 0.08 m<sup>3</sup>/s (i.e. 0.038 m<sup>3</sup>/s) would enter the bioretenteion cell through the inlet as designed.


==Curb cuts gallery==
==Curb cuts gallery==

Revision as of 18:11, 31 October 2017

Sizing[edit]

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To completely capture linear flow travelling along a gutter perpendicular to a curb inlet, the inlet must be of width::

Where:

  • WT is the width of the inlet for complete capture (m),
  • Q is the design flow perpendicular to the inlet (m3/s)
  • S0 is the longitudinal slope ratio
  • n is Manning's 'n' (between 0.012 and 0.016 for concrete, depending on surface treatment), and
  • Sx is the cross slope ratio

Where the inlet width is constrained or the intention is to capture only a proportion of the flow, the ratio of flow entering the curb inlet may be calculated::

Where:

  • Rc is the proportion of flow entering the curb cut, and
  • W is the available curb cut width (m)

Example[edit]

A curb cut of 3 m is proposed as an inlet for an offline bioretention cell receiving runoff from an adjacent roadway. The gutter and the curb are made from smooth concrete with Manning's 'n' = 0.013. The x-slope is 3% and the longitudinal slope of the road is 2%. The design storm produces flow of 0.08 m3/s.

The width of inlet to capture 100% of this flow is::

The proportion of water entering the bioretention cell under these flow conditions would be::

48% of the 0.08 m3/s (i.e. 0.038 m3/s) would enter the bioretenteion cell through the inlet as designed.

Curb cuts gallery[edit]