？。
Really? It took me an hour by train.
Literal
True? I [topic-は] train [object-を] using 1-hour took-[insistence-よ].
A split utterance: an elliptical 本当? reaction, then the speaker offers their own experience. 電車を使って ('using the train') is a ~て-form verb phrase used adverbially — ~て can link clauses but also express means or manner. Note the masculine first-person 僕. かかる ('to take time / cost') is the standard verb for expressing duration or expense.