source: https://www.reddit.com/r/dataisbeautiful/comments/15uz539/city_street_network_orientation/
From the post:
Urban spatial order: street network orientation, configuration, and entropy
By: Geoff Boeing
This study examines street network orientation, configuration, and entropy in 100 cities around the world using OpenStreetMap data and OSMnx.
See full paper: https://appliednetsci.springeropen.com/articles/10.1007/s41109-019-0189-1
It's about the orientation of the roads, does the road align cleanly with the compass points or does it skew diagonal? So a clean N/S orientation results in a clean N/S line. When you look closely you'll see the results are mirrored across the axis as a result.