What occurs when an over-speed detection is triggered?

When an over-speed detection is triggered, the correct outcome involves a visual indicator, which typically manifests through the speed dial background changing color. This serves as an immediate and clear alert to operators regarding the train's speed exceeding safe levels. The specific choice related to the speed dial background turning yellow is indicative of a cautionary signal that prompts operators to pay closer attention to the train's performance.

In operational settings, visual cues like these are critical for ensuring safety and enabling quick responses to potentially hazardous situations. The yellow color often serves as a warning rather than a definitive alarm or automatic response, which may signal that while there's an issue, immediate corrective actions like slowing down might not yet be necessary.

Other potential outcomes, such as an alarm sounding in the control room or the speed dial background turning red, typically represent more urgent alerts or emergencies, while automatic slowing down may not happen solely based on visual cues but rather requires further intervention based on the operational protocols in place.