Hello,

Pardon my curiosity but it looks like "motor_vehicle=designated" was not used correctly.  As an access tag, it is basically a synonym for "motor_vehicle=yes".

OSM uses a cascaded access model, where "access" gets overriden with other tags.  If you set access=private but also allow every major category of users explicitely (foot, bicycle, horse, motor_vehicle), routers will grant access to… absolutely everyone.

This "deesignated" value only exists because in some countries (mostly the UK and Germany) there are very specific rules that some roads are only allowed if a street sign says so; but nothing of this kind exists in Belgian law, and we should never use it.

I bet you should remove this tag entirely.

Hope this helps.