Conduit-Physical: Section Type: Culvert
To use these attributes, you must set Section Type to Circle or Box.
Conduit-Culvert Attributes
| Attribute | Description |
|---|---|
| Is Culvert? | Lets you choose whether or not the section type for the selected conduit is a culvert. If you select True , the other Culvert attributes are enabled in the Property Editor. If you select False , none of the other Culvert attributes are available in the Property Editor. Note that not this option is not available for ellipse and pipe arch section types. |
| Inlet Description | Lets you type or select a description for the inlet. Click the Ellipse (...) button to display the Culvert Inlet Coefficient Engineering Library, where you can select an existing culvert. |
| Culvert Equation Form | Lets you select Form 1 or Form 2. To use this field, you must set the Section Type to Circle or Box and the Is Culvert? attribute to True . |
| C | Lets you define the C equation coefficient that is used in the submerged inlet control equation. To use this field, you must set the Section Type to Circle or Box and Is Culvert? to True . |
| M | Lets you define the M equation coefficient that is used in both forms of the unsubmerged inlet control equation. To use this field, you must set the Section Type to Circle or Box and Is Culvert? to True . |
| K | Lets you define the K equation coefficient that is used in both forms of the unsubmerged inlet control equation. To use this field, you must set the Section Type to Circle or Box and Is Culvert? to True . |
| Y | Lets you define the Y equation coefficient that is used in the submerged inlet control equation. To use this field, you must set the Section Type to Circle or Box and Is Culvert? to True . |
| Ke | Lets you define the entrance loss value for the associated conduit. To use this field, you must set the Section Type to Circle or Box and Is Culvert? to True . |
| Kr | Lets you define the reverse flow loss value for the associated conduit. To use this field, you must set the Section Type to Circle or Box and Is Culvert? to True . |
| Slope Correction Factor | Lets you define the Slope Correction Factor to be used in inlet control calculations. Normally this factor is –0.5, but for mitered inlets, HDS No. 5 suggests +0.7.To use this field, you must set the Section Type to Circle or Box and Is Culvert? to True . |
| Has Overtopping Weir? | If True, this allows the user to specify a section of roadway that acts as an overtopping weir in the event that the culvert headwater elevation exceeds the roadway elevation. When set to true, Bentley StormCAD will include the overtopping weir in the elevation-discharge-tailwater (EQT) calculations for the culvert crossing. Weir flow is computed assuming the road acts as a broad-crested weir. Flow that passes over the overtopping weir will discharge to the same downstream node as the culvert. This field is not available when using either Gradually Varied Flow solver (Convex or Rational) because the overtopping calculation is not supported in these solvers. |
| Elevation (Roadway Crest) | The elevation of the roadway crest. If the culvert headwater elevation exceeds this elevation, flow will overtop the roadway and the roadway will act like a weir. |
| Roadway Cross Section Length | The length of the roadway section acting as a weir when flow is overtopping the road. Often this is set equal the top width of flow in the channel upstream of the culvert. |
| Use Weir C-Depth Table? | If True, this lets you define a table of weir coefficient versus flow depth values to simulate a weir coefficient that changes as the flow depth changes. This attribute is not available when using the SWMM solver. |
| C-Depth Table | A table of weir coefficient versus flow depth values. To use this field you must set the 'Use Weir C-Depth Table?' field to True. This attribute is not available when using the SWMM solver. |
| Roadway Weir Coefficient | The weir coefficient for the roadway (typically between 2.5 and 3.1 for US units, or between 1.4 and 1.7 for SI units). This coefficient is considered dimensionless and is used in the broad crested weir equation (see "Broad-Crested Weir"-374) to compute the flow that overtops the roadway. To use this field you must set the 'Use Weir C-Depth Table?' field to False. |
| Depth (Maximum Overtopping) | This value is used to determine the maximum headwater elevation to use when computing the culvert EQT table (maximum headwater equals 'Elevation (Roadway Crest)' plus 'Depth (Maximum Overtopping). To ensure accurate calculations this value should be set higher than the maximum expected depth of flow over the weir; however users should note that using very large values for this field may slow down model computations. If the headwater exceeds the highest elevation in the EQT table Bentley StormCAD will linearly extrapolate the values. |
| Increment | The depth increment used to generate EQT curves. A small value provides more accuracy but reduces the performance. |
| User Defined Tailwater? | If True, this lets the user specify the maximum tailwater elevation used when computing the culvert EQT table. If False, Bentley StormCAD will chose a maximum tailwater elevation based on the geometry of the downstream element (for example if the culvert discharges to a channel downstream, Bentley StormCAD will use the channel's top water level) |
| Elevation (Maximum Tailwater) | Lets you define the maximum tailwater elevation used when computing the culvert EQT table. To ensure accurate calculations, this elevation should be greater that the highest expected water surface elevation at the element immediately downstream from the culvert; however users should note that using very large values for this field may slow down model computations. To use this field you must set the 'User Defined Tailwater?' field to True. |