Symbolize lines so that no connected lines share same color

[SteveCole]

I know this has been asked before and I cannot find what the answer was and don't have it in my bookmarks. The situation is that you have a line layer with many features (too many to use unique values renderer) but you want to symbolize them so that no two features of the same color touch. From memory, a post suggested a tool in the Toolbox that does this analysis in order to add a field which you can then symbolize your layer on. This allows you to see the individual limits of each feature in the layer. You can also specify the number of options you want (4, 5, etc).

I just can't seem to find this. Help a foggy brain out. Thank you!

Steve

[SimonSchütte_ct]

For Polygons there is Calculate Color Theorem Field (Cartography)—ArcGIS Pro | Documentation
I am no aware of a tool that does this for lines.

You could try generating a buffer around your lines (with appropriate settings), use the Color Theorem Tool and then do a Spatial Join to transfer the attributes to your line feature class.
Select appropriate Match Option and only the Color Theorem field to join.

Buffer* around lines:

Color Theorem on Buffer:

Spatial Join (largest overlap)

This last step may need some trial and error to achieve best results for your use case.
Results may vary based on the Match Option,...*
Additional steps may be required to achieve the desired results.

*There are different buffer options: Buffer -> dissolve by ObjectID to generate buffer segments for each line segment // depending on the settings you may need to delete overlapping buffers