I've cleaned up a few of these and this one. It does appear Hannah you're working with the best intentions to improve the tagging, but the way you've made these changes has introduced data issues due to the duplication of the ways. In JOSM what you'll need to do is add a node to the existing way (shortcut key is A), then press escape to stop it from continuing it as a way. You can now swap back to select mode (shortcut key is S), and select the node you added on the way, then under Tools > Split way. You'll now have split the way and can set different tags for the different segments. I believe this is what you've been trying to do .