I live in NJ. access road. The driveway is set up for our kids play on. There's a tree swing that swings across the driveway that was here previously. One day car flew into our driveway, almost hitting my daughter .I had to tell my kids to stop playing to let these cars go down.
We had a family cookout yesterday and parked cars down the driveway because some of the older folks couldn't walk down the hill from the top. I don't understand why people use our driveway with all the signs we have up. It sounds bad but ,we don't taxes to let other people use what we pay for. We chose this house do to the privacy and "safe yard". My daughter has to get off of her swing to let a car come into our driveway.

Can we put anything across the driveway without asking anyone?
No.