What is the key factor in determining following distance?

The key factor in determining following distance is the speed of the vehicle you are following. When vehicles travel at higher speeds, they require a greater following distance to allow sufficient time to react to any sudden stops or changes in traffic conditions. The faster a vehicle travels, the longer it will take to come to a complete stop; therefore, maintaining an adequate distance is essential for safety.

While weather conditions can certainly affect stopping distances, they are more of an influencing factor rather than the primary driver for determining following distance in general driving situations. Similarly, the size of the vehicle in front can impact the perception of distance, but it does not change the fundamental necessity to adjust following distance based on your own speed. Traffic light color is irrelevant to following distance as it pertains to immediate traffic signals rather than the dynamics of safe driving distance.