What does a yellow box on the road indicate?

A yellow box on the road is a traffic control measure designed to ensure the free flow of vehicles at intersections. It indicates that drivers should only enter the box if their exit is clear; this means that if the intersection ahead is congested and there isn’t enough room to completely cross, drivers should wait behind the line until they can proceed safely without blocking traffic. This helps prevent gridlock and improves the overall efficiency of the roadway.

In this context, the other options do not correctly reflect the meaning of the yellow box. Proceeding with caution typically refers to situations where there might be hazards but does not specifically relate to the rules about entering an intersection. Yielding to pedestrians applies to crosswalks but is unrelated to the yellow box's purpose. Stopping for emergency vehicles is critical, but it is governed by different signage and road laws. Understanding the meaning of the yellow box is crucial for maintaining smooth traffic flow and preventing accidents at intersections.