Chris Barrington-Leigh and I have been working for the past few years to assess the completeness of the street network in OSM. We’re pleased to have now published our results in the journal PLoS ONE. Thanks to many suggestions from the OSM community on our preliminary analysis.

Here are the highlights from the paper’s abstract:

We find (i) that globally, OSM is ∼83% complete [as of January 2016], and more than 40% of countries—including several in the developing world—have a fully mapped street network; (ii) that well-governed countries with good Internet access tend to be more complete, and that completeness has a U-shaped relationship with population density—both sparsely populated areas and dense cities are the best mapped; and (iii) that existing global datasets used by the World Bank undercount roads by more than 30%.

An update using the April 2017 snapshot suggests that completeness is now ~89%. Our more detailed results and all our code are available on GitHub. Here’s a sample of the largest 10 countries (updated through 2017), showing the actual growth in OSM road length and our model fits: ![Growth in OSM dataset] (https://people.ucsc.edu/~adammb/Documents/fitted-top10best.jpg)

And here’s the fraction complete, also updated through April 2017: ![Fraction complete map] (https://people.ucsc.edu/~adammb/Documents/OSMmap-frcComplete_best.svg)

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