What is the main purpose of the VFR hold line?

The main purpose of the VFR (Visual Flight Rules) hold line is to mark the boundary of the runway environment. This line serves as a visual cue for pilots and vehicle operators to ensure safe separation between active runways and taxiways. By clearly delineating where aircraft should hold before entering the runway, the VFR hold line helps prevent potential runway incursions, which can lead to dangerous situations. Understanding the significance of this boundary is crucial for maintaining airfield safety, as it defines where vehicles and personnel must stop and remain clear of active runway operations.

In contrast, the other options refer to different functions that do not directly relate to the specific purpose of the VFR hold line. Indicating traffic flows pertains more to the design of taxiways, while highlighting vehicle parking areas and signifying maintenance zones relate to ground operations but are not the primary focus of the VFR hold line.