I hope to have my chicks out of the run when I'm outside working or porch sitting while the weather is nice. Behind and both sides of me is cattle-fenced field, but in the front there is a fairly busy state road 250 feet from the house. There's a plank fence across the front except for a driveway opening. How secure can I be that they won't head for the highway, and what strategy can I use to ensure they don't or call them back if they wander too far in that direction? Thanks!