What is the purpose of a yellow traffic signal?

The purpose of a yellow traffic signal is to prepare drivers to stop as the signal is about to turn red. When a traffic signal turns yellow, it serves as a warning that the light will soon change to red, signaling that vehicles should come to a stop if it is safe to do so. This transition phase is crucial for safety, as it helps to prevent accidents that could occur if drivers were not alerted to the impending change.

A yellow light also signals to drivers that they should assess their situation—if they are too close to the intersection to stop safely, they may continue through, but for those further away, it is a clear signal to begin braking. Other options, such as signaling free traffic movement, indicating pedestrian right-of-way, or promoting acceleration, do not align with the primary purpose of the yellow signal, which is focused on safety and controlling the flow of traffic in anticipation of the red light.