How must hazardous materials transported by rail be labeled on the sides of the railcar?

Hazardous materials transported by rail must be clearly labeled on the sides of the railcar to ensure safety and effective communication regarding the contents of the car. The use of 4" letters is mandated to provide a highly visible identification of the materials being transported. This size ensures that individuals working in proximity to the railcars, including emergency responders and other personnel, can easily read the labels from a safe distance, enhancing situational awareness and safety measures.

Using a smaller font size would diminish visibility, potentially leading to confusion or misinterpretation of the materials being transported. Conversely, larger letters could create issues with the labeling space or the overall aesthetics of the railcar, but the regulation emphasizes a balance of visibility and practicality with the 4" letter standard, making it the correct choice for hazardous materials labeling.