Sewer line flow symbol

[MikeHenson]

I am using a shape file for my sewer lines, each line has an upstream elevation and a downstream elevation field.  Is there a way to show my line pointing to the downstream elevations, thus showing the flow of the sewer line?  Thanks for any help you can give.

[RichardFairhurst]

I am using a shape file for my sewer lines, each line has an upstream elevation and a downstream elevation field.  Is there a way to show my line pointing to the downstream elevations, thus showing the flow of the sewer line?  Thanks for any help you can give.

It can be done if either the lines were digitized to point in the flow direction or if the lines contain an attribute that indicates whether the digitized direction is with or against the flow direction. 

I would add 2 double fields to calculate the From and To end Z values.  The formula in the Field Calculator is a Python calculation of either Shape.FirstPoint.Z! (From Z) or !Shape.LastPoint.Z! (To Z).

Where the From Z value is greater than the To Z value the flow is with the digitized line direction and where the opposite is true, the flow is against the digitized direction.  You then would have the option of actually flipping the lines to orient them with flow direction, or leaving them as digitized and adding and calculating another field to indicate how the lines are oriented.  If you use the field then you would use a Value Classification symbols that uses two separate symbols and the appropriate arrowhead direction to fit the flow direction field value.

[MikeHenson]

so I had to draw them in the direction of flow for that to work? I was hoping I could just use the arrow to point to the "ds_elev" (for downstream) field. Not possible?

[RichardFairhurst]

so I had to draw them in the direction of flow for that to work? I was hoping I could just use the arrow to point to the "ds_elev" (for downstream) field. Not possible?

I never said that and in fact my post said the exact opposite.  Regardless of how you drew the lines to begin with, you can determine the flow direction from correctly assigned Z values with a simple binary field.  Once the lines are classified with a simple binary value, then you have the choice of using either that binary field value to symbolize the lines without reorienting them or actually reorienting the lines.  You never said what your fields contained and I assumed the Z values were on the line geometry.

I have no idea what your ds_elev field contains, so I don't know if it can be used or not.  If your ds_elev field contains actual Z values, then it should not be directly used for symbology, since it is not a predictable value.  If ds_elev is just a Z value number that gives no indication of which end of the line it is associated with, then that is not sufficient for solving this problem.  But from actual Z values that are correctly associated to the ends of your lines, you can derive a field that sets up a simple binary indicator of flow direction with yes/no, true/false, 0/1 or any other binary values.

If ds_elev is a yes/no, true/false, 0/1 or other binary indicator of whether the lines are with or against the downstream flow, set up the Symbology as Categories on that field and use a Cartographic line to add arrowheads to point the appropriate direction based on that field.

Once you have a field that simplifies the classification of the line flow direction, then there is also a Flip tool that could actually use selections based on that value to reorient the upstream oriented lines if you wanted them to actually point downstream.  Use of the Flip tool is optional and your lines do not actually have to point downstream to symbolize them correctly.

[MikeHenson]

sorry for the confusion, and I appreciate your reply. To answer your question, I have actual elevations in the "us_elev" and "ds_elev" fields.  FOr instance, US could be 501.00 and DS could be 499.9, indicating that I want the arrow pointing to the lower number.

Forgive my ignorance, as I am really new at this!

Mike

[RichardFairhurst]

sorry for the confusion, and I appreciate your reply. To answer your question, I have actual elevations in the "us_elev" and "ds_elev" fields.  FOr instance, US could be 501.00 and DS could be 499.9, indicating that I want the arrow pointing to the lower number.

Forgive my ignorance, as I am really new at this!

Mike

These two fields do not tell you the orientation of the flow direction of your line, since the values are not clearly assigned to the beginning or end of the line.  All you know is one end is higher than the other, but not which end is up and which is down.  Either the line had to be drawn consistently downstream or consistently upstream to know which end of the line to point toward, or you have to have actual Z coordinate values assigned to the line geometry to find out which end is the lower end.  Orientation has to be intentionally established when creating line features and cannot be determined simply by looking at two fields that have no clear no correlation to the line ends.

Potentially using linear referencing to create routes that combine the sewer line chains together as events could tell you how the lines are oriented, but that takes about two dozen geoprocessing steps to manipulate the lines and end points to derive the line orientation.  It is not something that is in a ready made help file and I would have to write out custom instructions for you to follow.  That is beyond what I can offer at this time.