To Practicing Witches/Pagans: Rhoda needs a warding spell

Hey guys.

I don't know if something like this exists, but I'm trying to ward a driveway. Y'know, like one of those long, gravelly ones for a house in the mountains. The idea here is to either keep anyone who means my MC harm from using it and coming up to the house, OR to make the people in the house aware of who's coming before they get there--like a sort of paranormal doorbell/intercom system. (Bad analogy, I know.)

I know you can ward a room, or a threshold, but I wasn't sure about the driveway.

Thanks in advance!

Thanks guys, and to the folks who PM'd me as well!

As for my MC: This is a sixteen-year-old boy who's being asked by his mentor (also a male witch) to ward part of their new property (that being the driveway) as practice--supervised, of course. He's sort of a witch-in-training. I haven't aligned him with any particular faith, at least not yet. He's also coming from a history of violence and abuse--two years prior to the events in my WIP, he was the apprentice of a very bad, very dark magician who made him hurt people with his natural talent for magic. This new mentor is trying to help him get a fresh start and use his abilities more responsibly. (I'm aiming to promptly throw a wrench in that, of course, but I'm not quite to that point yet.)