WikiProject Belgium/Boundaries/Part-municipalities

Sections (FR), deelgemeentes (NL), Teilgemeinden (DE), Part-municipalities (EN) are no longer official administrative divisions. They were independent municipalities, until the big municipality merge in the 1960-70's. The boundaries are however rather well-known, because many people (certainly in rural areas) still refer to these old municipalities. Most are also still signposted.

As the boundaries don't exist anymore, the OSM boundaries are just estimates based on old maps (Vandermaelen). A second option is to use Statbel's statistical sectors, which are mostly identical to the old borders.

We map these part-municipalities in a boundary=administrative relation with admin_level=9

Resources

• Statbel statistical sectors as a geojson file. https://statbel.fgov.be/nl/open-data/statistische-sectoren-2022. Joost has made a geojson file that can be loaded in JOSM into a seperate layer. The file was shared in our OSM BE Matrix chat room. Get the geojson file here. These borders are not 100% equal to the part-municipality borders.

• NGI-IGN has a good layer showing all the boundaries. Unfortunatly, it cannot be used to map from, due to copyright reasons. It can be found here. Although you cannot use it to map from, it can be handy to have in JOSM to quickly navigate, see the names of the part municipalities, and especially: see where the Statbel statistical borders are not equal to the real part-municipality borders. You can add it as a JOSM image layer using wms:https://wms.ngi.be/inspire/admin/service?FORMAT=image/png&TRANSPARENT=TRUE&VERSION=1.3.0&SERVICE=WMS&REQUEST=GetMap&LAYERS=municipsection&STYLES=&CRS={proj}&WIDTH={width}&HEIGHT={height}&BBOX={bbox}
• The Vandermaelen map has pretty good outline of the old part-municipality borders. This map can be used to manually trace boundaries. JOSM image layer for Wallonia wms:https://geoservices.wallonie.be/arcgis/services/CARTES_ANCIENNES/VDML/MapServer/WmsServer?FORMAT=image/png&TRANSPARENT=TRUE&VERSION=1.3.0&SERVICE=WMS&REQUEST=GetMap&LAYERS=0&STYLES=&CRS={proj}&WIDTH={width}&HEIGHT={height}&BBOX={bbox} and for Flanders https://geo.api.vlaanderen.be/histcart/wms?FORMAT=image/png&TRANSPARENT=TRUE&VERSION=1.3.0&SERVICE=WMS&REQUEST=GetMap&LAYERS=vandermaelen&STYLES=&CRS={proj}&WIDTH={width}&HEIGHT={height}&BBOX={bbox}

Workflow.

1. Check which part-municipalites are missing with this overpass query
2. Using the NGI-IGN layer in JOSM navigate to the missing part-municipality
3. Open the Statbel Statistical sectors geojson file mentioned above.
4. Check if the borders of the Statbel polygon are the same as the NGI-IGN layer. Most of the time, they are 100% equal. Sometimes, Statbel has two part-municipalities in one statistical sector.
   1. If the polygon in the file is 100% equal to the actual borders, split the multipolygon at each intersection. (I find it helps copying the polygon to a seperate layer).
   2. If Statbel has a missing border, you will have to trace it manually from the Vandermaelen layer.
5. In a new layer, download the OSM data of the area.
6. Create a relation with the following tags: type=boundary, boundary=administrative, admin_level=9, name=*. (or use a neighbouring relation and duplicate it).
7. Copy the missing boundaries from the geojson file layer into the osm data layer.
8. Add the boundaries as members of the relation, with role set to 'outer'. You now use both the missing borders you just copied, and the existing borders. You might have to merge the node connecting existing and new borders, so the relation shows a fully closed loop.
9. Add the node that hase the place=* tag to the relation with role set to 'admin_centre". This can be quicly found using an image layer of Openstreetmap.org, and zooming in on the name.

Some additional remarks:

1. It's handy to use filters in JOSM
2. Be careful with boundary=postal_code. Sometimes they are individual ways, sometimes they reuse admin boundaries.
3. Be careful with already existing boundaries (eg the admin_level=8 boundaries). You can either just use those as members in the new realtion. Or you could also update existing boundaries with the ways from the geojson file. This way, the geometry can be improved. For this, I copy the new boundary on top of the existing boundary and use "Replace geometry" in JOSM.
4. Be carefull when existing borders are together with roads, landuse, etc.. Perhaps it's better to separate them.
5. Be carefull when using 'Merge nodes' in JOSM, as sometimes boundaries are stuck to landuse, or highways.