铁老大

Traditional (Taiwan): 鐵老大

tiělǎodà ㄊㄧㄝˇ ㄌㄠˇ ㄉㄚˋ

    • the railway system or its departments (mocking, dated)

Character by character

Saying俗语俗語

Idiom惯用语 · Widely known

Literally
iron big brother
Meaning
A nickname for the railway system or its departments, which act high and mighty and are slow to improve management or service. Mocking, dated.

Sources