Mapping highway exit numbers on OpenStreetMap

Oindrila Gupta
Fri, 06 May 2016 00:00:00 -0400

Exit numbers are an essential part of guidance in navigation systems. To reach your desired destination, your navigation system should be able to guide you to the correct exit when driving on highways.

Image source: crosscountryroads.com

We collaborated with the community to inspect the coverage of exit numbers on OpenStreetMap and add missing ones in 9 states in the US. We chose these states based on the density and availability of Mapillary street photographs. Depending on the data present in the Mapillary images, we added the ref=<exit_number> tag to motorway junctions that have exit numbers and we added the noref=yes tag to junctions that lack an exit number.

After working on this project for two weeks using the checkautopista2 tool and reviewing more than 220 highways, we found that exit numbers are already well-mapped on OpenStreetMap. In total, we added 63 exit numbers (ref tags) and 219 noref tags in California, Florida, New Jersey, Maryland/DC, Pennsylvania, Washington, Colorado, Texas, and Illinois using Mapillary imagery, Wikipedia, and the state DOT documents.

Map showing the exit numbers added by the team. The pink dots represent ref=* tags and the blue dots represent noref=yes tags added by the team.

Join the mapping!

If you are interested in adding exit numbers in your state, read our guide on adding exit numbers and Your first steps with JOSM to get warmed up, then jump into our exit number mapping project.

If you have questions or more ideas for mapping exit numbers, find me on OpenStreetMap or Twitter.