Problem

When computing a model in StormCAD (or with the GVF-Rational solver in SewerGEMS or CivilStorm), the program hangs and says that it is not responding.

Solution

The following are some possible reasons for this. In general, it is best to ensure that you are using the latest version of the product

1) Unsolvable Inlet capacity equations - One possible cause of this is the settings of catch basins in the model. It can occur if the inlet capacity equations cannot be solved based on the min and max range. In this case, the issue was resolved in the cumulative patch set for version 10.00.00.45 and in future full releases. Reference # 746305

2) Bad input data for Pipe-Arch conduits - Another cause will be if incorrect data is included with the pipe-arch conduit type. In this case, you will see a user notification indicating what needs to be changed when validating the model. Correct the pipe-arch catalog entry to resolve this. In a future version, a validation message will be included instead of the hang. Reference # 749306

3) Circular pipe convergence issues - If this occurs in a model with circular pipes, you can also try setting the "Use explicit depth and slope equations" calculation option to "True". This option was introduced in V8i SELECTseries 3 (08.11.03.XX).

4) Modified Basket-Handle convergence issues - If this occurs in a model with conduits set as "Modified Basket-Handle" as the shape, you may be encountering a known issue that was addressed in a patch to version 10.00.00.45 (and included in future versions). The issue involved such conduits operating in the range between the top of the vertical side portion of the Modified Basket-handle and the half-circle top portion. The patch ensures that the program consistently treats such conduits per their definition (as seen in the help). In this definition, the "Rise" of the conduit is only the vertical side of the rectangular portion at the bottom of this shape (with the half-circle part at the top rising further above this), whereas previously some parts of the program (including profiles and the "full capacity" figure) treated the "Rise" as the full height of the shape. Reference #766303.

Please contact Bentley Technical Support for more information.

5) Structure loss Method - In some cases, this has occurred due to the structure loss method selected in the calculation options (EGl or HGL). Try toggling this to see if it has an impact. 

6) Diversions without a flow split - if a conduit is set as a diversion link (is diversion link = true), there should be one other conduit connected to the upstream node, as diversions are only needed with a flow split. If you have a situation where a series (linear path) of conduits has one conduit set as a diversion, this can cause the program to hang.  In this case, please choose "false" for "is diversion link". Reference # 866580.

7) Invalid use of the lateral link element - check to make sure that any lateral link element used in the model has only a single catchbasin node element on the upstream side, and a tap on the downstream side. If there is a network of elements upstream of the lateral, you will need to use a conduit instead, with a node (such as a transition) on the downstream side, splitting the conduit that it connects to. Reference defect # 915622.