What is a filter light?

A filter light refers specifically to a green arrow that provides permission for drivers to proceed in a particular direction while other traffic may be stopped. This type of signal ensures that vehicles can safely make turns or move forward without having to yield to oncoming traffic, which enhances the flow of vehicles at intersections and minimizes the risk of accidents. In this context, the filter light functions as a guidance mechanism that clearly directs drivers, allowing for more efficient use of road space.

The other options either represent different types of traffic signals or serve different functions. For instance, a red light is a clear signal to stop, which does not align with the definition of a filter light. A light that changes based on traffic refers to adaptive traffic signals that adjust based on current conditions but is not specific to the actions permitted by filter lights. Lastly, warning lights for pedestrians serve to alert drivers of pedestrian crossings, which is unrelated to the specific directive of a filter light. Understanding the purpose of a filter light is crucial for navigating intersections safely and for overall road awareness.