Ryan Lambert: Find missing OpenStreetMap data with PostGIS

The #30DayMapChallenge
is going on again this November. Each day of the month has a different theme
for that day’s map challenge. These challenges do not have a requirement
for technology, so naturally I am using
OpenStreetMap data stored in
PostGIS with
QGIS for
the visualization component.

The challenge for Day 5 was an OpenStreetMap data challenge.
I decided to find and visualize missing
crossing tags.
Crossing tags are added to the node (point) where a pedestrian
highway (e.g. highway=footway) intersects a motorized highway
(e.g. highway=tertiary).
This post explains how I used PostGIS and OpenStreetMap data to
find intersections missing a dedicated crossing tag.

Without further ado, here was my submission for Day 5.

Map of the Denver, Colorado metro area with a shaded hex grid overlay. Title reads "% of Footway Intersections missing Crossing".  Subtitles read "Denver Metro area, November 2021" and "#30DayMapChallenge - 2021 Day 5: OpenStreetMap". The hex grid is shaded from light red to dark red (5 gradients), with only 4 of the lightest shaded areas around Denver proper.  Throughout the rest of the inner-metro area are shades 2-4 (35% through 94% missing) with most of the outer regions in the 100% or "no data" area.