What is the typical use of UN numbers in transportation?

UN numbers are primarily utilized to identify and manage hazardous materials during transportation. Each UN number corresponds to a specific dangerous good, providing vital information about the nature of the substance, including its hazards, handling requirements, and necessary precautions. This identification system helps ensure that carriers, handlers, and emergency responders can quickly and accurately recognize the type of hazardous materials they are dealing with, which is essential for safe transport and compliance with regulations.

In this context, the other options do not accurately reflect the primary purpose of UN numbers. While proper packaging is crucial for safe transportation, the UN number's primary role is not strictly related to packaging. It serves more broadly to identify hazardous materials rather than to classify shipping routes or record shipping costs. Thus, while packaging, routing, and cost recording are important aspects of logistics, they are not the main functions of UN numbers in the context of transporting dangerous goods.