。
The train is running on schedule.
Literal
Train [topic-は] timetable [in-accordance-with-どおり] is-running.
ダイヤ is a katakana loanword from English 'diagram,' specifically meaning 'train timetable' in Japanese — a specialized sense not found in other varieties of English. どおり ('in accordance with,' a rendaku variant of 通り) attaches directly to ダイヤ. 動いている ('is moving/running') uses the resulting-state ~ている to describe the ongoing operational state.