Final answer:
The transport index is used for radioactive materials, ensuring safe transport by limiting radiation exposure based on DOT regulations.
Step-by-step explanation:
The hazard class that utilizes a transport index to determine how much of it can be loaded onto a single vehicle for transport is the class for radioactive materials. This index is designed to help ensure that radioactive materials are transported safely, limiting exposure to individuals and the environment. The transport index is a number assigned to a container that indicates the maximum radiation level at one meter from the surface of the container. According to the United States Department of Transportation hazardous materials regulations, the summation of transport indexes for all packages in a single vehicle cannot exceed 50 to ensure safety during transportation.