Spanning Pipe Labels Calculating Incorrect Slope

[C3D-Nash]

Well this is a bit worrisome.  I notice issues using spanning pipe labels for the first time recently after having used them for years.  The slope calculated by the spanning pipe label is completely wrong.  I've attached a picture in which Iabeled two pipes connected by a null structure.  The two labels on the bottom are the pipes labeled indivually at 3.53% and 3.34%.  When labeling them as a spanning pipe, if I choose the downstream pipe first and them the upstream pipe it shows me a slope of 0.48%.  If I choose the upstream pipe first, then it gives me 2.88%.  Either way it's wrong.

As I was writing this I decided to check and see if the pipes were flowing the same direction (Start to End or End to Start).  Turns out they weren't.  After flipping one of the pipes around so that they both are laid out in the same direction (Start to End from Upstream to Downstream) the label now reads 3.37%, which is correct.

Seems like an the label should honor the flow direction of the pipe, no matter if they have been laid out in opposite directions or not.

[castled071049]

The label subtracts the end elevation of the last pipe in the series from the start elevation of the first pipe in the series, then divides by the total length of the spanning pipe series. For this reason, it is absolutely paramount that you layout your pipes in the direction indicated on the pipes layout toolbar. (i.e., if it's pointing "downhill", layout the pipes from highest elevation to lowest elevation.) Failure to do this will result in erroneous pipe spanning labels, as you found out. 

We always create a non-plotting profile along the flowline of the profiled pipe run that indicates the slope in order to correctly label the profile view bands. A side benefit is that you can see if your pipe spanning label slope is the same as the created profile slope label. If not, you probably have to switch some pipes end-for-end.