1、This is a narrow-gauge railway.
這是一條窄軌鐵路。

2、In the south they are putting in a wide-gauge track to replace the old narrow-gauge lines.
在南面，他們正在鋪設寬軌的鐵道兒代替原先的窄軌的鐵道。

3、Content: the shijiazhuang-taiyuan line is the first state-owned narrow-gauge railway in China.
正太鐵路是中國第一條國有窄軌鐵路。

narrow-gauge翻譯