That is soo scary!! I can totally relate!
A few weeks ago my friends and I went out Christmas carroling. I figured we might as well stop by my house so I can let the dogs out (no one was home) so I go and take Tucker out of his cage and just as I put him down my friend Mary comes in to help me with Rusty and Tucker is GONE. I never saw him run so fast in his life. Meanwhile I was flipping out and crying and screaming. If it wasn't for my friends catching him, I don't know if we'd have him today. It was so scary! Just like you all I could think about was him getting hit by a car. If he had gone in the other direction he would have headed right onto the turnpike!
Anyway, I'm glad you had a happy ending! I'm so sorry you had to go through that!