The data team at Mapbox has been trying out mapping missing motorway exit numbers in the US. Based on the density of Mapillary street photographs, the following 9 US states were chosen to improve:

• California
• Florida
• New Jersey
• Maryland + DC
• Pennsylvania
• Washington State
• Colorado
• Texas
• Illinois

We used the checkautopista2 tool which made it very easy to detect exits that lack a ref tag. In summary we found most of these exits to have no official exit number and added the https://wiki.openstreetmap.org/wiki/Tag:noref=yes tag when we could confirm it on official documents or on Mapillary photographs.

These are the exit numbers added by the team. The pink dots represent https://wiki.openstreetmap.org/wiki/Key:ref tags and the blue dots represnt https://wiki.openstreetmap.org/wiki/Tag:noref=yes tags added by the team, click here to view the full map

The team has been working on this from 31 March 2016 to 14th April 2016 and reviewed more than 220 highways.

• Number of https://wiki.openstreetmap.org/wiki/Key:ref added by team on nodes https://wiki.openstreetmap.org/wiki/Tag:highway=motorway_junction are 63
• Number of https://wiki.openstreetmap.org/wiki/Tag:noref=yes added by team on nodes https://wiki.openstreetmap.org/wiki/Tag:highway=motorway_junction are 219

This is the workflow that was used for this mapping activity. Would be great to hear your feedback on how it can be improved for further such tasks, please drop a comment here or on the project tracker.

Happy Mapping!