At least in Finland and Sweden those highways-as-emergency-airfields are always in use, no need to prep the area or remove dividers in any way. They are mostly used by the army for practicing, basically the police will just close the road so the army can practice, and when the army is done the road is opened again.
https://moottori.fi/wp-content/uploads/2023/07/Kesabaana23-T...