A yellow traffic signal serves a critical safety role in traffic management. Its primary purpose is to alert drivers that the traffic light is about to change from green to red. This indication provides a warning to drivers to prepare to either stop safely before the intersection or, if they are too close to the intersection to stop safely, to proceed with caution.
In urban traffic control, the yellow light acts as a transitional signal, aiding in the flow of traffic and reducing the chances of drivers running a red light. This crucial function promotes safety for both vehicle operators and pedestrians by ensuring that drivers have adequate time to react as the traffic situation changes.
The other options refer to different functions that traffic signals or signs serve. For example, pedestrian signals instruct pedestrians when it is safe to cross, speed limit signs inform drivers of legal speed restrictions, and construction signs warn drivers of road work ahead. These signs and signals operate under different principles and signal different actions, making them distinct from the role of a yellow traffic signal.