No building permit as long as the land is not developed?

yes, we know that. Our property was preceded by a parcel that was fully developed and declared as a "planned public traffic area," but nothing official was filed with the office. So our building permit was denied until we clarified the development obligation. By the way, a building application can sometimes take several months. If the gravel road is to become a public traffic area, the owner should talk to the city to have it officially registered. Then it might be possible to save yourself the trouble and the money with the EBL.

Who is the owner of the gravel path?

Just think of the city.

Then your property is formally developed and you will receive a building permit through a regular building application. You may need to clarify whether you will lay and pay for the connection yourself or if a supplier will do it.

Ask your architect, he knows that.

Best regards
Dirk Grafe

Okay thank you for the answers