A placarded vehicle must have at least ____ placards?

A vehicle that is transporting hazardous materials is required to display placards in accordance with DOT regulations, specifically to indicate the presence of hazardous materials to responders and the public. The correct answer specifies that a placarded vehicle must have at least four placards.

A placarded vehicle typically has placards on each side and at the front and rear of the vehicle. This is crucial for safety and helps ensure that anyone who comes into contact with the vehicle, such as emergency responders or law enforcement, is immediately aware of the hazardous materials being transported. The placement of four placards provides necessary visibility from different angles, which is essential in a variety of situations, including accidents or roadside emergencies.

Having only two or three placards would not adequately communicate the presence of hazardous materials from all vantage points, increasing the risk of misunderstandings or accidents related to the hazardous contents. Therefore, the requirement for four placards is a safety regulation designed to protect both the public and emergency personnel.