There were multiple points stacked on the same coordinates that I did not notice.

I am trying to count the number of points within 10km of lines (routes) so the routes can be styled according to the number of points within proximity. However, the results are not turning out as expected. Using Carto Builder, I created a 10km distance buffer around the points. On the lines layer I added the analysis for Intersect to the buffer layer with the count operation. However, when I check the results the count is incorrect (or rather, now what I want). For example, there are 6 points show below but results for the counts on the lines vary from 11, 12, 21, and 23.

enter image description here

I then tried the reverse to see why the results were behaving in this manner. I created 10km distance buffers around the lines (routes). On the points layer I added the analysis for Intersect to the buffer of the lines with the count operation. These results were accurate.

I welcome any suggestions on a different perspective of the problem, even if it requires a SQL query instead of the built in analyses.

  • If you are trying to count the number of points that overlap with your lines, your second approach is the right one. In fact, you have pointed out that the results were accurate. Your main approach is wrong. Commented Feb 13, 2019 at 8:22

1 Answer 1


I'm not familiar with Carto Builder, but you do not want to do an analysis intersect. I can't tell by your illustration, but based on the counts you are getting it would seem that the approach you used is treating them as sliver polygons rather than overlapping buffer polygons. There are several approaches but the easiest would be to use overlapping point buffers and Spatial Join intersect, many to one (point buffers to lines) to get a count of point buffers.

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