Note that generally, OpenStreetMap requires information to be verifiable on the ground. Proposed features that are not visible on the ground should therefore only be mapped in exceptional cases and after a discussion with the relevant OSM community, lest they might be deleted for lack of verifiability.
https://wiki.openstreetmap.org/wiki/Key:proposed:*
Also da sollte dann wenigstens ein Schild stehen: “Hier entsteht…”