。
The train arrived on schedule.
Literal
Train [topic-は] on-scheduled-time [adverbial-に] arrived.
定刻に here uses the bare locative に without 通り, with a slightly different nuance from the fuller 定刻通りに: 定刻に means 'at the scheduled time,' while 定刻通りに means 'in accordance with the schedule.' The difference is thin.