The Hidden Sign

A few minutes ago I picked up my teenage daughter at a friend's house. I'm driving along a kind of rural road with dense foliage along one side. I notice that there is a yellow road sign up ahead, but I can't make out what it says. The surrounding tree branches have grown around it so much that it is mostly obscured. Being the curious type of person I am, I slow my car down substantially to figure out what the sign says. Turns out that it says...

Hidden Driveway.

Now THAT's useful!!