Which of the following is NOT necessary to know for determining the need for placards?

To determine the need for placards for hazardous materials transportation, it is essential to understand the properties and risks associated with the materials being transported, as well as regulatory requirements. The type of materials being transported and their weight are crucial factors because they influence the classification of the hazard and the required signaling to ensure safety during transport.

The manufacturing date of the materials does not impact the need for placarding. While it could be relevant for certain regulatory compliance or for assessing the stability of the materials, it does not directly influence the immediate visibility of risk or the classification system used for placarding.

Understanding the transportation route taken is important for assessing potential risks based on the environment or population density, but it does not determine if placards are needed for the materials themselves. Thus, while the type, weight, and route are critical for placarding considerations, the manufacturing date is not a necessary factor in this context.