I have a road network and for every road segment the average number of daily traffic. I need to draw a map where the line width for each road segment is proportional to the daily traffic. I can do this in ArcMap using the proportional symbols symbology, or in QGIS using a data defined property in the line style (where the pen width is proportional to the daily traffic using some scaling formula). However, at junctions, the graphic representation is not optimal because the line ends are (of course) exactly overlapping (like in A in the image below). A more correct representation would be that the lines are adjacent at the junctions, like in B in the image below.

typical line representation in GIS (A), and how I would like to have it (B)

I could manage some part of this problem using the date defined properties in QGIS on the line offset, but it is still far from being optimal. It also gives the new problem of misalignment at the end of the segment (top right in the image below), and a problem with the line labels. This is for now the best I could manage:

QGIS rendering using data driven properties

Is there any way to achieve this type of rendering like in B in the first image, in QGIS or ArcGIS/ArcMap? Or is there any other GIS software which gets this type of rendering correct?

closed as too broad by PolyGeo Jan 25 '17 at 10:11

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • I don't know that it's possible with GIS software. The topic frequently comes up with flow maps (which I've replaced the road tag with, since it could apply to flow in any network and not just roads). The first place I'd try experimenting with is the line end cap settings. After that, at least in ArcGIS, I'd look at Cartographic Representations. I don't know you'll be able to get lines to 'split off' one another, but you might reduce/eliminate the 'step down' effect at the junction. – Chris W Feb 25 '15 at 21:08
  • Please decide which of ArcGIS desktop and QGIS you wish to ask about in this question. Otherwise you are effectively asking two questions which goes against the Tour. – PolyGeo Jan 25 '17 at 10:11
  • After having tried with both ArcGIS and QGIS without big success, I must say it seems it is not possible currently with any of these software packages, and is probably beyond the scope of GIS software in general. – chkaiser Jan 26 '17 at 6:20