# Creating a buffer based on the number of parallel lines

I am working on a project for a gas pipeline and I am trying to create a study area based on the pipeline alignment. The problem is that there are multiple pipelines within the right-of-way and the study area must be different widths based on the number of lines that run parallel to one another. For example, a single pipeline must have a 25' buffer, a double pipeline must have a 37.5' buffer and a triple pipeline must have a 50' buffer.

Is it possible to do this without going through and manually selecting the linework and individually buffering them?

I have been working on this for a few hours and I have had no luck.

I am using ArcMap and I have an advanced license.

• What constitutes parallel? If two pipelines run on identical bearings but are 500m apart, are they counted as equally parallel as similar pipes that are only 2m apart. Can you provide a little more information about the pipes please? Oct 5, 2017 at 16:35
• After visual inspection of the pipelines I believe that 500' would be the cutoff, anything over would no longer be considered parallel. Oct 5, 2017 at 16:39

## 2 Answers

You might Buffer the Centroids of the Pipelines, run a Spatial_Join of Pipelines/Buffers to get a Count of the Pipelines at that location. Finally, Spatially join the Count back to Pipelines so you can Buffer based on Count.

One possible solution (with an advanced licence) that springs to mind is to collapse dual lines to center lines (see here), setting maximum width to cover the cutoff. Then buffer the centerline by the cutoff and count the features in it.

You will need to merge your lines or possibly cut them to ensure this operation gives a sensible result. For instance if you have a single pipe represented by several segments, then dissolve by pipe-id first.

• The pipelines appear to be too irregular for the collapse dual lines tool to work. Oct 5, 2017 at 17:01