Final answer:
A motorist must stop before the single solid white line at an intersection when facing a traffic signal or sign. This regulation aids in slowing down speeding vehicles and provides a safer crossing for pedestrians, contributing to overall road safety.
Step-by-step explanation:
A single solid white line across a road at an intersection signifies a point where a motorist must stop. According to traffic rules, a motorist must stop before the line when facing a traffic signal or stop sign. This line serves as a critical safety feature to manage vehicle and pedestrian traffic.
For instance, if vehicles frequently speed through an intersection regardless of speed limits, a traffic signal enforces that motorists slow down. This is to prevent potential accidents and to offer pedestrians, such as students coming to or leaving campus, a safer opportunity to cross the intersection.
Furthermore, in emergency situations, such as a pregnant woman in labor enroute to a hospital, some jurisdictions may offer exemptions to the strict adherence to traffic signals, but typically, the rule to stop before the solid white line is mandatory and ensures the collective safety of all road users.