# HY8:Increased Resistance in Culverts

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Jump to navigationJump to searchThe increased resistance dissipator type can be used for either box culverts or circular culverts. Variables for these energy dissipators are described below.

## Increased Resistance in Box Culverts

The input variables required for this calculation are the following:

- h/r
_{i}—Ratio of roughness element height divided by hydraulic radius taken about the top of the roughness element. - Height of the roughened section (h)

## Increased Resistance in Circular Culverts

The input variables required for this calculation is the following:

- L/D
_{i}— Ratio of roughness element spacing divided by the diameter of the culvert opening at the roughness element. (Range = .05 to 1.5) - h/D
_{i}— Ratio of roughness element height divided by the diameter of the culvert opening at the roughness element. (Range = .005 to .1). - L
_{r}/P_{i}— Ratio of the roughness length to inside perimeter (Range = 0.0 to 1.0) - Diameter of roughened section (Opening, D
_{i})

The following figure shows the flow regimes and variables for an increased resistance energy dissipator implemented in a circular culvert.

Variables from the figure

- L — Length from beginning of one roughness element to the beginning of the next roughness element.
- h — height of roughness element
- D
_{i}— diameter of roughened section (opening)