in the process of (doing something or happening); while (doing)[cedict]
铁道
tiě dàoㄊㄧㄝˇ ㄉㄠˋ
railway line; rail track[cedict]
上
shàngㄕㄤˋ
on; on top; upon; first (of two parts); previous or last (week etc); upper; higher; above; previous; to climb; to go into; above; to go up; to attend (class or university); third tone of putonghua[cedict]
做工
zuò gōngㄗㄨㄛˋ ㄍㄨㄥ
to work with one's hands; manual work; workmanship[cedict]