Which type of material requires a stop at railroad crossings?

• A. Placarded Class 7 (RADIOACTIVE) material
• B. Placarded Class 1 (Explosives)
• C. Placarded Class 3 (Flammable Liquids)
• D. Placarded Class 2 (Gases)

Answer: (A)

When you’re transporting hazardous materials in quantities that require placards, you must come to a complete stop at railroad grade crossings. This rule exists because a train can approach quickly, and a leak or exposure from a hazmat shipment near the crossing could be extremely dangerous. Among the material types listed, radioactive (Class 7) shipments are emphasized for this crossing-stop rule because of the heightened safety controls and radiological safeguards that are routinely applied at crossings. The halt allows time to verify the crossing is clear and to follow any specific radiological procedures before proceeding. So, the most pressure on the crossing-stop rule in this context is placed on radioactive materials, though the overall requirement applies to placarded hazmat transports in general.