International Mileage Charts: Frequently Asked Questions
- How can you compute mileages for relatively obscure countries?
- How can I report an error with a city?
- How can I report an error with the road data / add new road data?
- Why are there many blank routes in the charts?
- A city is listed in the wrong country.
- A country is listed in the wrong continent.
- Do you have fastest route and/or travel time charts?
- Do you have the charts in any other formats?
- I have downloaded a ZIP file which does not make sense!
How can you compute mileages for relatively obscure countries?
We do this by using the OpenStreetMap road database and the GeoNames city database. Both are open source datasets which try to provide a global coverage. This is the only affordable solution and probably the most complete that is readily available.
How can I report an error with a city?
Errors with cities (eg. centroid locations, populations, and Anglicised spellings) should be reported to GeoNames. Your corrections will then appear in our next chart calculation. We intend to recalculate the charts every 6-12 months, and track our improvement statistics.
How can I report an error with the road data / add new road data?
OpenStreetMaps has a very active community of volunteer mappers. Join them and correct the error and/or add the missing data. This will improve the road data for everyone, and we will incorporate it in our next chart calculation. We intend to recalculate the charts every 6-12 months, and track our improvement statistics.
Why are there many blank routes in the charts?
The routing data and engine are both bidirectional - ie. a route reprots the same distance for both directions. Therefore each city pair only has one route calculation, and the chart will appear in "lower triangle" form. This is in contrast to our North American and European mileage charts, both of which list bi-directional charts.
Blank routes are also reported for cities which cannot be matched with road data (orange cells), and for routes which cannot be calculated due to the lack of any connecting roads (pink cells). The lack of real roads in the database will eventually be corrected as this data is added to the OpenStreetMaps database. If you live in the area concerned, you can help OpenStreetMaps yourself. Your efforts will appear in our next set of mileage charts.
Blank routes due to a lack of roads can also occur because there really aren't any roads connecting the two cities. This can occur between islands, and in remote parts of the world.
A city is listed in the wrong country.
A country is listed in the wrong continent.
Although it is possible that there is an error in the source Geonames database (see: How can I report an error with a city?), city and country allocations are based on UN determinations and ISO designations. If a city or country is re-allocated in the Geonames database, this change will be reflected in our next set of chart computations.
Do you have fastest route and/or travel time charts?
At the moment it is not possible to compute this type of information efficiently for the international charts. However, we do have this information in the US, Canadian, and European "version 3" charts.
Do you have the charts in any other formats?
We are currently computing the charts using Microsoft Excel 2007 'XLSX' format. This format is widely used, and many people find it the easiest format to use. It also supports 1000 column tables and formatting.
However, we are considering producing future charts (ie. with data updates) using 'CSV' (Comma Separated Value) files instead. These are more widely supported but lack color shading and freeze panes. They can be easily imported into spreadsheet programs such as Excel, or read by third party software. Would you prefer CSV or XLSX format charts? Let us know using our contact form.
I have downloaded a ZIP file which does not make sense!
The charts are supplied as XLSX files which can be read by Excel 2007 (and later). Internally these files are actually zipped XML files. This confuses Internet Explorer 8, which insists on changing the extension from xlsx to zip. Microsoft may issue a patch, but the problem has not been fixed as of November 2010. One solution is described here. We would also recommend the use of a different browser, eg. Firefox.
