Chris Barrington-Leigh and I have been working for the past year to examine the history and completeness of the OSM road network. We're interested to hear your thoughts and reactions, particularly about why completeness varies so much across countries.
Our rough estimate, to be refined, is that the world's roads are now over 90% complete. It's not only European and North American countries that seem complete, but also lower-income countries such as Haiti (presumably thanks to the Humanitarian OSM Team).
You can see the country-by-country history, along with estimated saturation points, here. The y-axis indicates the length of ways; the scale varies depending on the country.
A few notes on the methods:
- we are only looking at completeness in terms of length.
- the data are for roads only (i.e., ways tagged "highway-" and one of the following values: “motorway,” “motorway_link,” “trunk,” “trunk_link,” “primary,” “primary_link,” “secondary,” “secondary_link,” “tertiary,” “residential,” “road,” “unclassified,” or “living_street").
- we used two methods: we modeled the shape of the S-shaped curve for each country, and used satellite imagery to count missing road segments for a random sample of grid cells.
- we'll release the code as soon as we clean it up a little more.
We're excited to share these preliminary results, and hope to get your thoughts.
Adam & Chris