Using Element Property Inferencing to populate missing elevations or elements

  Applies To 
SewerGEMS, CivilStorm, StormCAD,  SewerCAD
  Version(s): CONNECT Edition, V8i


Can missing elevations or elements be populated automatically between two known elevations or known elements?


This can be done using the Element Property Inferencing tool.

There are two general use cases for this tool

  1. Layout new manholes - In this case, the user knows the elevations of the manholes at the beginning and end of a run and the physical properties of the downstream conduit, but has not yet placed the manholes and pipes in between. The user indicates the number of manholes that will be places in the gap and they will automatically be inserted. This is useful in laying out new systems.

  2. Follow existing path - In this case, the user has laid out the manholes and the conduits between them. The user employs this tool to assign properties to the elements between the upstream and downstream nodes. This is more useful in filling in details of the system when the path is already determined whether for a new or existing run of conduits.

Note: if you have (or need) catchbasins instead of manholes, morph the existing catchbasins into manholes first (use the layout tool and click on top of the catchbasin), then use the tool. If new manholes are created which should be catchbasins, select all of them, then use the Batch Morph tool to convert the selected manholes into catchbasins.

More information on using this tool can be found in the 'See Also' section below and in the Help documentation included with the software.

Another option would be to take some constant and subtract that from the ground elevation if you have that. This can be done in the node flextable by adding the ground and invert elevations, copy/paste the ground elevation to the invert, then right click the invert field column header, choose global edit, then subtract the desired depth. For this case you may need to do some research on typical pipe laying practice.

Troubleshooting and Additional Assumptions

1. The element property inferencing tool doesn't interpolate invert levels between drop manholes, i.e. when the start & stop invert levels are different. It would only work when the "Set invert to start/stop?" property is set to 'True'. This will be considered for a future version - reference enhancement  #175199.

2. For pipes with the same diameters, inferencing invert levels will also inference the crown levels, which is generally the case. Meaning generally, a pipe leaving a manhole has the same diameter as the pipe entering the manhole, so in this case matching inverts will match crowns as well. But when diameters are different, you could raise the the downstream end of the inflowing pipe to match the outgoing crown. 

3. Currently there is no way to batch-run element property inferencing. If you have a large area of missing elevations with multiple branches and known ground elevations and you want to set constant slopes between known inverts at the upstream ends and downstream known inverts, you will need to run multiple passes. The new elevations from interpolation of one branch will determine the known stop invert elevation for another connecting branch.

4. If you encounter the error "invalid starting link" when trying to lay out new elements, try laying out a conduit between the upstream and downstream manhole.


See Also

How do I run the element property inferencing tool with a negative slop or an adverse slope?

Inferring ground elevation from surrounding elements