I would like to tell you about another small project I will be working on for the next months. It is made possible by a NLNet NGI Zero Discovery grant:
Missing maxspeed
Inferring default speed limits for situations where concrete maxspeed information is missing. Last time I checked, only 12% of roads had this tagged at all and while the number of roads tagged with maxspeed of course is increasing, so is the number of roads.
Compared with highway=unclassified, it looks pretty much like a zero sum game.
This means, that not only did OSM based router software always have to fill huge holes in data to produce reasonably precise ETAs (etc.), it is also not something that will get any better on a global scale in the foreseeable future.
Why so sketchy?
It’s also understandable why the data is so sketchy: Roads can simply be traced from satellite imagery. Finding speed limit signs on the other hand often requires to look for them on-site or via good Mapillary / KartaView coverage which is in itself already much more time-intensive. Not only that - it’s even more time-intensive to confirm that there is no signed speed limit for a given segment of road as the speed limit sign could be located all the way down the road. (One reason why the speed-limits quest is disabled in StreetComplete.)
Finally, if it turns out there is no sign, tagging the correct maxspeed requires knowing the traffic legislation in the country one is mapping in. (And sometimes one errs in what one thinks is correct. Did you know that the default no-speed-limits in Germany are technically are not limited to the Autobahn?)
