Final answer:
The person watching a placarded vehicle must stay aware of the potential hazards indicated by the placards.
Step-by-step explanation:
When observing a placarded vehicle, it's crucial for the observer to remain vigilant and understand the hazards denoted by the placards. These placards, typically affixed to transport vehicles carrying hazardous materials, convey vital information about the contents being transported. They indicate the type of hazard—whether it's flammable, corrosive, toxic, or otherwise dangerous. By recognizing these placards, individuals nearby can take appropriate precautions, such as maintaining a safe distance or notifying authorities if necessary. Moreover, understanding the placards aids in emergency response situations, allowing responders to take swift and informed action. Being attentive to these indicators ensures the safety of both the observer and others in the vicinity, minimizing the risk of accidents or incidents involving hazardous materials.
Remember, staying aware of the potential hazards indicated by the placards is essential when watching a placarded vehicle.