About the International Mileage Charts
The International Mileage Charts consist of mileage charts for all countries with more than one city with a population of at least 1000 people (exceptions are the US and the UK due to high road densities).
Unlike our North American and European mileage charts, the International Mileage Charts use OpenStreetMap data. OpenStreetMaps is the only data source for road routing data that attempts to cover the entire globe and is also affordable. GeoNames is used to provide city locations and populations for each country.
The quality and coverage of OpenStreetMap data is decidedly variable. Therefore we have also provided some very basic statistics that attempt to indicate the data coverage. Statistics indicate the percentage of cities which can be matched to road data, and the percentage of routes that can be found. A road data match occurs if road data can be found within 10km of a city location. Note that these statistics are very limited but should give a guide as to a mileage chart's completeness. An example where they fail would be for a nation that incorporates many islands, because routes cannot be calculated between islands. We plan to recalculate these charts every 6-12 months, and to track the improvements in coverage over time.
All mileage charts are supplied as Microsoft Excel 2007 (.xlsx) workbooks consisting of one worksheet. This worksheet lists the 1000 largest cities with a population of at least 1000, and consists of the shortest distances for each route between these cities. Cities (and their routes) that cannot be matched are marked in orange, whilst routes that cannot be calculated are marked in pink.
Computations
Routes are calculated using pgRouting, PostGIS, and PostGres. OpenStreetMaps data is loaded into PostGIS using osm2po. The entire stack is scripted with Python. All of these packages and data sources are open source:
Errors in cities locations, Anglicised spellings, and populations should be reported to GeoNames. Corrections to the road data should be given to the OpenStreetMaps project. We plan to recalculate these charts annually, so your data corrections will be incorporated into the next set of table calculations.
