Final answer:
A single, solid white line across the road at an intersection is a stop line, where vehicles must halt. It helps control vehicle speed and enhances pedestrian safety at the intersection.
Step-by-step explanation:
A single, solid white line across the road at an intersection typically indicates a stop line. This line is where vehicles are required to stop when they approach an intersection with a stop sign or traffic signal. It is not a crosswalk nor a marker for a passing zone or no passing zone. The presence of a traffic signal helps in regulating vehicle speed, as drivers must slow down and cannot speed through the intersection when the light is red. Moreover, a traffic signal contributes to pedestrian safety, as it allows students and other individuals to cross the intersection at appropriate times without needing to dodge traffic.