What is the purpose of a yellow traffic light?

The purpose of a yellow traffic light is to indicate that the light is about to change from green to red. This serves as a warning to drivers that they should prepare to stop if it is safe to do so. The yellow light provides a brief period for drivers to make a decision about whether to safely stop their vehicle or proceed through the intersection, thus enhancing overall traffic safety. Understanding this function is crucial for drivers to react appropriately and avoid potential accidents or violations.

The other options do not accurately reflect the role of the yellow light. For instance, signaling drivers to accelerate contradicts safe driving principles, while allowing pedestrians to cross is typically associated with pedestrian signals rather than traffic lights for vehicles. Lastly, indicating that traffic is flowing smoothly does not align with the purpose of a yellow light, as its function is more about caution and transition rather than the actual flow of traffic.