Way cool! That is how we got our showgirl chicken. Found her on the road near our house (we live out in the sticks). Had her for about 9 months and she is great.
Good luck with her, she is lucky you came along when you did.
Poor thing does look abandoned, but you might want to put a classified in your local newspapers under "Lost and Found" to make sure it doesn't have an owner looking for it. Then keep and love!
Looks like a mixed breed girl to me. It also appears that she has a tiny girl spur on her leg. It's not unusual for hens to have small ones.
My thought is that maybe she hitched an unexpected ride on a truck or something. When I was little, a neighbor's chicken took a ride home to our house in the engine compartment of my dad's truck. She made herself at home and laid eggs for us.