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How to make a slope rule for sewer runs

KyleMCSE

I need help with creating a rule to calculate the slope of sanitary sewer runs. I have always calculated it as UPELEV-DOWNELEV/Shape.Length

I used to manually do this in ArcMap but I would do it in batches after I finished an area. I was able to create a rule using the code below. I am not a coder but when I try to check it to see if it is working properly I get another answer that is pretty different. For example, a line returns a slope of 0.045 using the below code but when I manually do the calculation using the UPELEV, DOWNELEV, and SHAPE.Length() I get a slope of 0.013. I have tried to replace Length(Geometry($feature)) in the code with SHAPE.Length() and it works in the rule but in the execution ArcPro kicks out an error.

Any help would be greatly appreciated.

// ************* End User Variables Section *************

// Limit the rule to valid asset groups

if (!Includes(valid_asset_groups, asset_group)) return $feature.slope;

if (IsEmpty($feature.UPELEV) || IsEmpty($feature.DOWNELEV))

{

return $feature.slope;

}

if (IsEmpty(Geometry($feature)) || Length(Geometry($feature)) == 0)

{

return $feature.slope;

}

return ($feature.UPELEV - $feature.DOWNELEV)/Length(Geometry($feature));

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Accepted answers

Ayan Palit

@KyleMCSE Try the sample:

https://github.com/Esri/arcade-expressions/blob/master/attribute-rules/attribute_rule_calculation/CalcSlopeOfLine.md

KyleMCSE

Yes I did but I had to create a rule to get the length into a field that could be used in a calculation. There was already a field that could be used (measuredlength) that was not getting used so I attached the rule to populate that field. The expression I used was:

Length($feature, 'feet')

I then adjusted my rule to calculate the slope to:

Limit the rule to valid asset groups
if (!Includes(valid_asset_groups, asset_group)) return $feature.slope;

if (IsEmpty($feature.UPELEV) || IsEmpty($feature.DOWNELEV))
{
return $feature.slope;
}
if (IsEmpty(Geometry($feature)) || $feature.measuredlength == 0)
{
return $feature.slope;
}
return ($feature.UPELEV - $feature.DOWNELEV)/$feature.measuredlength*100;

All comments

Ayan Palit

@KyleMCSE Try the sample:

https://github.com/Esri/arcade-expressions/blob/master/attribute-rules/attribute_rule_calculation/CalcSlopeOfLine.md

KyleMCSE

The first expression in the link you posted is the same as the one I used. We don't use the Z value even though I have the elevation attribute. My question is where does this point: Length(Geometry($feature))

I looked in my attributes and cannot find where that would be pointing to. I feel like this is the issue because it is the only thing I cannot find within the attributes.

Ayan Palit

Length(Geometry($feature)) is not an attribute field but queries the shape/geometry of the feature.

REF: https://pro.arcgis.com/en/pro-app/latest/help/data/databases/dbms-data-types-supported.htm

Ayan Palit

@KyleMCSE Curious if you got this to work? Please post the solution for others in the community.

KyleMCSE

Length($feature, 'feet')

I then adjusted my rule to calculate the slope to:

Limit the rule to valid asset groups
if (!Includes(valid_asset_groups, asset_group)) return $feature.slope;

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