Why are there diagonal yellow lines at major junctions?

Diagonal yellow lines at major junctions are primarily intended to prevent blockage of the junction. These lines serve as a visual cue to drivers, indicating that they should not stop their vehicles in that area. This is particularly important in high-traffic locations and intersections, as stopping within the marked zone can lead to congestion and hinder the flow of traffic. By keeping these areas clear, it helps maintain a smooth and safe passage for all vehicles and pedestrians at the junction.

The other options do not accurately reflect the purpose of diagonal yellow lines. While improving visibility, ensuring pedestrian safety, and indicating speed limit changes are essential aspects of road safety and signage, they are not the specific intent behind diagonal yellow lines at intersections. These lines focus on traffic flow management and reducing the likelihood of gridlock at critical points on the road.