| Clue | Source | Date |
|---|---|---|
| Proceeding vigorously | ||
| Well under way | The Times Concise | 24 Mar 2024 |
| At the peak of activity | USA Today | 27 Aug 2022 |
| At the height of activity | The Times Concise | 17 Dec 2018 |
| Operating at peak capacity | ||
| Operating at maximum | ||
| Well underway | ||
| Operating at capacity | ||
| Busy busy | ||
| Operating normally | ||
| Going strong | ||
| Operating at capacity |