Parametric Trench Description and Mass Calculation¶
Parametric Trench Description¶
Parametric trench description requires that manholes and pipes are entered in the chain definition data command. Since geometry and properties for manholes and pipes are imported to an application layer, we have a dedicated function in the toolbox to transfer this data to chain definition data in an SFI model.
Create Water and Wastewater Chain Definition Data from Application Layer¶
Icon for Create Water and Wastewater Chain Definition Data from Application Layer**
With the function Create Water and Wastewater Chain Definition Data from Application Layer, we point to the lines in the application layer that will form the centerline of the trench.
When designing with chain definition data, we construct points for the manhole center. Furthermore, we enter pipe levels, which refer to the manhole wall.
Figure: 1 = Level 1, 2 = Level 2, A = Manhole center
Note therefore that application layer lines that go to the center point of the manhole will be adjusted accordingly in the process of creating chain definition data from geometry in the application layer. Level 1 and Level 2 become equal to the center height.
Illustration of adjustment for application layer lines
Survey Instructions for Gemini Water and Wastewater
For as-built data following the Survey Instructions for Gemini Water and Wastewater, it is required to measure a point in the manhole wall when surveying a gravity pipe. It is necessary to measure as close to the manhole wall as possible, and this can be done either on the inside or outside of the manhole wall.
Figure: Measurement point for gravity pipe at manhole wall
For pressure pipes, the pipe is measured all the way to the fitting or valve in the manhole.
Figure: Measurement point for pressure pipe at fitting/valve
Pipes should be measured with NEH at all horizontal and vertical direction changes, as well as at all joints, connections, and branches.
How are these transferred from application layer to chain definition data?¶
In chain definition data, all pipes must pass through the manhole's center point. Where this is not the case, invisible lines will be created, that is, points with manhole dimension and pipe dimension equal to 0.
Maximum point distance determines whether lines with gaps should connect or not:
Illustration of maximum point distance
Note
If the pipe does not have any vertices within the manhole area, no manhole will be created in the chain definition data.
Based on buffer distance, the program finds other lines that should be included in the same trench:
Illustration of buffer distance
Prerequisites for successful conversion¶
For the function to work smoothly, we must prepare the points (manholes) and lines (pipes) in advance with the correct codes.
The prerequisite is that they have key properties with valid codes, minimum:
- Lines in the application layer must have S_FCODE and Dimension
- Points in the application layer must have S_FCODE, ManholeShape, Width, and Cone
Cross-reference for application layer and chain definition data¶
Included in the installation is a cross-reference table for the template Gemini VA.al_. This links attributes in the application layer with attributes in chain definition data. We can use this as a starting point and create our own tables for similar data with other attribute schemas than Gemini Water and Wastewater.
The table below shows properties and codes for points in the application layer, which use the XREF table for the Gemini Water and Wastewater template or schema, and how they are transferred to chain definition data:
| PROPERTY | CODES | CHAIN DEFINITION DATA |
|---|---|---|
| S_FCODE | MH - Manhole | The point for center bottom manhole provides North and East coordinates for the manhole. The point's height value is not used as the pipes provide Level 1 and Level 2. |
| LID - Manhole cover | The point for center manhole cover provides terrain height for the manhole. | |
| Width | Width is given in mm | Manhole dim is given in m in chain definition data. Width value is converted from mm to m. |
| ManholeShape | R - Round | The combination of ManholeShape and Cone determines manhole type |
| Cone | R - Straight cone | RR gives manhole type: 2 |
| S - Angled cone | RS gives manhole type: 3 | |
| U - Without cone | RU gives manhole type: 1 | |
| Dist_BottomInsideUnderOutside | Distance in m | Value for Off.bottom is adjusted so that the manhole's external bottom is correct |
The table below shows properties and codes for lines in the application layer and how they are transferred to chain definition data:
| PROPERTY | CODES | CHAIN DEFINITION DATA |
|---|---|---|
| S_FCODE | SW - Stormwater pipe SWR - Stormwater retention SWC - Stormwater channel SWO - Stormwater overflow pipe SWD - Stormwater ditch SWT - Stormwater tunnel |
Data type: 101 Stormwater data |
| WW - Wastewater pipe CS - Combined sewer WWS - Wastewater siphon WWC - Wastewater channel WWO - Wastewater overflow pipe WWT - Wastewater tunnel |
Data type: 102 Wastewater data | |
| WS - Water supply pipe WSI - Water supply intake pipe WSC - Water supply channel WST - Water supply tunnel WSF - Flushing pipe |
Data type: 103 Water supply data | |
| SWP - Stormwater pressure pipe WWP - Wastewater pressure pipe WWS - Wastewater suction pipe |
Data type: 104 Pressure pipe | |
| DR - Drainage pipe | Data type: 105 Drainage pipe | |
| Dimension | Dimension is given in mm | Pipe dim is given in m in chain definition data. Dimension value is converted from mm to m. |
| Material | The material list can contain all types of codes (max. 8 characters). They are transferred unchanged. | Same codes as in the application layer. |
Info
Regarding parametric trench description, this is the same whether we are designing Water and Wastewater with chain definition data or documenting as-built Water and Wastewater with chain definition data.
Parametric trench description is described in more detail in the Water and Wastewater Design chapter under the subsection on Parametric Trench Description and Mass Calculation.