noun
normal operation; running normally
Used for transport services (trains, buses) operating on schedule without disruption.
台風の影響で遅れていたが、現在は平常運転に戻っている。
It was delayed due to the typhoon, but it has now returned to normal operation.
noun
business as usual; normal state of affairs
Colloquial extension: things are proceeding as they always do, often with a nuance of 'same as ever' or 'nothing special'.
彼が遅刻するのはいつものことで、今日も平常運転だ。
Him being late is nothing new; today is business as usual.