What factor can reduce the visibility of emergency lights?

The visibility of emergency lights can be significantly reduced by the presence of headlights, particularly when they are on bright or high-beam settings. When another vehicle's headlights are shining directly or in close proximity to emergency lights, the brightness can obscure the emergency lights' visibility. This is because both light sources compete for attention, and the human eye can be overwhelmed by the more intense light, making it harder to notice the less intense flashes of emergency lights.

In contrast, factors such as road construction, rain conditions, and driver distraction can contribute to reduced visibility in various ways, but they do not directly interfere with the output of the emergency lights themselves. Road construction might create obstacles or divert attention, while rain can create reflective surfaces that scatter light. Driver distraction can limit awareness of surrounding vehicles. However, none of these factors impact the visibility of emergency lights in quite the same direct manner as the interference caused by other vehicle headlights.