Do you mean to ask: “Can I get a restraining order against my abusive ex that prevents him/her from using the same public transportation as I do?”
If so, the answer is: probably not. Unless you can show that whenever your ex knows where you are, your ex abuses, attempts to abuse, or threatens to abuse you, the court would almost certainly not take such extreme measures.
Protecting you from legitimate and serious risks of abuse is one thing, but preventing your ex from using public transportation—assuming your ex needs to use public transportation to get to school, and/or work and/or , and/or the grocery store, and/or the doctor, etc.—would be overreaching. Instead, the court could still issue you a restraining order against your ex, but on a limited basis, i.e., not barring your ex from the same bus or train, but ordering your ex to avoid eye contact with you, not to speak to or gesture at you, not to sit next to you, and to move as far as possible to the back of the bus/train, for example.
Utah Family Law, LC | divorceutah.com | 801-466-9277