In American English, we would say "I'm on 30th Street." I am assuming that the street name is "30th Street". I live on "South Plain Road". This is an example conversation that I might have with a friend of mine.
Sara: What are you up to right now?
Me: I'm shopping downtown.
Sara: Do you want to meet up for coffee?
Me: Sure.
Sara: Ok. I can meet you. Where are you at right now?
Me: I'm on South Plain Road. Do you know where it is?
Sara: Yes. Are you closer to the town common?
Me: Yes.
Sara: Okay. I'll meet you there in five minutes.