Is it okay for my manager to change my time schedule?

My manager changed my schedule without my knowledge or permission and the time she is putting me on is not correspondent to the CTA (Chicago Transit Authority) time schedule, Therefore in order for me to make it to work on time I would have to walk some distance very early in the morning in a very dangerous neighborhood. I have provided her with my bus schedule but she is still being very unreasonable so I was wondering is it okay for her to do this to me?