Suggested merger workflow
From OpenStreetMap Wiki
Please only attempt to do a merger using JOSM you are likely to fail in a big way with any thing else.
- mark the specific merger task as in work on the list
- locate area in question
- locate one, preferably the largest, of the boundary relations that need to be merged
- open the relation in question in the relation editor (download all elements of the relation)
- make a (backup) copy of the relation
- add the way elements from the boundaries of the areas that need to be merged to either the copy or the original (there are arguments for both methods, in some cases we are talking about completely new entities in other cases not), you can do this by simply marking the ways in the relation and using copy paste.
- I typically change the type of the relations to old_boundary or similar so that the work can be tracked easier.
- once you have added all the ways you need to delete the internal border ways that are unnecessary (and will be duplicates), the net result should be one or more closed ring(s)
- change the BFS reference number and the name to the new one (if they have actually changed)
- delete the old relation or the copy
- delete the boundary relations for municipalities that don't exist any more
- delete any unused boundary ways (they should have no relation memberships any more if they do, investigate).
- mark the task as done
- some people may argue that the old boundaries should be retained as sub-entities of the municipalities, however with the exception of the large cities they typically do not have any legal or administrative meaning and as far as we know, nobody actually maintains the borders after the mergers (aka they vanish from the SwissTopo dataset too)
- you should check that there is a place node for every municipality that actually corresponds to an inhabited location that is merged
- adjustments to the GWR road statistics will be made as soon as possible once the mergers are complete