urban roll transit的用法和樣例：
例句
- Traction calculation of trains is one the important composing of the whole urban rail traffic.
列車牽引計算是整個城市軌道交通的重要組成部分。 - With more overhead railway lines built in a city, it is worried about the railway accident occuring on the overhead urban railway.
摘要隨著城市軌道交通高架化的大力推行，救援人員必須對高架橋上的起複搶修進行預案準備。
