OpenStreetMap
Sometimes ways have duplicate nodes in them. I.e. instead of:
A-B-C
the node IDs are:
A-B-B-C
I’m unsure how this can happen. Probably a software bug in some OSM client. I’m not really into mapping but I always wanted to reduce the warnings we print and so I took the chance yesterday and fixed every single duplicated node (only in ways used as roads - which resulted in approx. 100 problematic ways).
It was rather easy to get rid of this as GraphHopper prints the problematic way IDs while the import and in JOSM you can download way information directly via Ctrl+Shift+O. Then you click Shift+V (Verify), then you click fix, then you click Ctrl+Shift+Up and Enter. I reviewed the result on openstreetmap.org again and proceeded with the next way (Ctrl+F4 to restart in JOSM). Sometimes multiple nodes were duplicated but then you only need to verify the way again, after you fixed it.
To my surprise and thanks to JOSM keyboard shortcuts, it took not even 2 hours :) … see all the changes here.
There were also 2 or 3 mappers who seemed to have the same goal and already fixed a few of these bugs.
Discussion
Comment from Sanderd17 on 6 May 2021 at 13:49
The first ones I noticed were originally mapped with the “Go map!” editor. So it seems likely that’s the curlpit.
They’re also very recent, so the bug likely is still around.
Comment from karussell on 6 May 2021 at 14:13
Do you mean this one? https://github.com/bryceco/GoMap There seems to be a related issue: https://github.com/bryceco/GoMap/issues/206
Comment from b-jazz on 6 May 2021 at 15:47
I do these when I find them as well. I also clean up where two different node IDs share the same exact lat/long pair. I have some scripts set up that will download the data from OSM Inspector and then parses it up into small areas so that I can work on several duplicates in a single changeset.
Thanks for helping with the cause.