The total transport index of all radioactive materials packages in a single vehicle must not exceed:

• A. 50
• B. 100
• C. 25
• D. 75

Answer: (A)

The key idea is that the transport index (TI) is the measure of radiation a package emits at a distance of one meter, and when multiple radioactive packages ride on the same vehicle, their TI values add up. Regulators set a cap so the overall radiation level on a single trip remains manageable and the true exposure risk—and placarding needs—are predictable. So the total TI for all packages on one vehicle must not exceed 50. If adding another package would push the sum past 50, you’d need to move some packages on a separate vehicle or adjust the load to stay within the limit. For example, packages with TI values of 20 and 25 total 45, which is allowed; adding a package with TI 10 would bring the total to 55, which would not be allowed on one vehicle.