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I performed Intersect Analysis on one polygon shapefile and one polyline shapefile. I didn't specify any tolerances, and both SHPs were projected into the same UTM before performing the analysis.

Expected behavior: one line criss-crossing a polygon will always be split into multiple lines

Actual behavior: lines are only sometimes split

Evidence: # lines input file = 2663; # lines output file = 2958; so, some splitting is happening. Image below is only one FID highlighted, but clearly is 3 segments and should be 3 separate FIDs

Am I using the wrong tool? enter image description here

  • Try running the multi-part to single part tool in Arc or select all features in the line file and start editing. Under advanced editing tools there is an "Explode" function. It may be that the intersect is giving you polylines which are multipart (ie: multiple lines in one feature or FID). – Keagan Allan Jun 23 at 22:01
  • thank you @Keagan Allan, that fixed it. For some reason I expected multipart polylines to have a different "Shape" type, but I guess they are just "Polyline." Thank you for the help. – AlexS1 Jun 23 at 22:41
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It may be that the intersect tool is splitting the lines as expected. The issue is coming from the type of feature being produced. It looks like the output is a multipart polyline. Which could best be explained as a line having multipart parts (sections) but the geometry of the line is held within one feature or FID.

There is a tool in ArcMap called the "Multipart to Single Part Tool"

Multipart to Single Part

From the documentation I see it is available from Basic Level, so you should be able to get a result. Run the tool using the output from your intersection and your feature count should increase quite a bit, and the example you have shown will no longer exist.

An alternative to this tool is the "Explode" function held within the "Advanced Editing" Toolbar. Which will help you if you do not want to create a new feature / shapefile from the intersected layer.

Advanced Editor

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