When approaching an Approach Sign, what must trains exceeding Medium Speed do?

When trains exceeding Medium Speed approach an Approach Sign, they are required to begin reducing speed immediately. This is critical because the Approach Sign indicates that the train is approaching a signal that may require it to stop or prepare for a lower speed limit. By reducing speed right away, the engineer ensures that the train can safely respond to the upcoming signal's indication, whether it involves stopping or moving at a restricted speed. Early speed reduction allows the train to react appropriately to changes in track conditions or signal indications while maintaining a safe stopping distance. This practice is essential for ensuring the safety of the train and other rail operations, as it helps prevent potential accidents or disruptions in service.