No, you're no unreasonable at all to want to move! It's very natural. I wouldn't actually do so in a hurry, though. I'm quite certain that you're just experiencing a random projection of the accident to the road, and it will in time be "over-written" by other memories and feelings.

Similar story: after my brother died a few years ago while I was away from home, I had to spend hours trying to get hold of my mother on my mobile phone, to tell her. The sight of the phone made me feel physically sick after a few hours, and I dearly wanted to throw the awful thing away. I ordered a new one, but before it arrived I had received sympathy messages from lots of friends on it, and it was back to just being a phone. I still have it.

Hope you do have many overlayers of good and pleasant experiences to balance out this one terrifying one in time!