Materials designated by PHMSA as posing a risk to health, safety, property, or the environment during transportation, including explosives, flammable liquids, poisonous gases, and radioactive materials. Hazmat shipments require proper classification, packaging, marking, labeling, placarding, and documentation under 49 CFR. Railroads have specialized procedures and routing requirements for hazmat movements.
The placement of diamond-shaped warning signs on railcars carrying hazardous materials to identify the hazard class and enable emergency responders to react appropriately. Placards are required under 49 CFR Part 172 and must be displayed on all four sides of the car. Correct placarding is a critical safety and regulatory requirement for hazmat shipments.
The DOT-defined design, construction, and testing standards that a tank car must meet to transport a particular hazardous material, designating requirements for shell thickness, head shields, thermal protection, pressure relief devices, and other safety features. Specifications are designated by alphanumeric codes such as DOT-111 or DOT-117. Matching the correct car specification to the commodity is a regulatory requirement.
A general-purpose non-pressurized tank car specification that was the most common type used for petroleum products and chemicals before safety upgrades were mandated. DOT-111 cars were found to be prone to puncture in derailments, leading to regulatory requirements to retrofit or replace them with DOT-117 standard cars. The phase-out of older DOT-111 cars for flammable liquids was a major regulatory initiative following the Lac-Megantic disaster.
The enhanced tank car specification introduced after the Lac-Megantic and other crude oil train disasters, featuring a thicker shell, full head shields, thermal jacket, and improved pressure relief valves. DOT-117 cars are required for Class 3 flammable liquids transported in certain quantities. The standard significantly reduces the risk of catastrophic releases in derailments.
The U.S. DOT agency that regulates the safe transportation of hazardous materials by rail, highway, air, and pipeline. PHMSA sets specifications for tank car construction, placarding requirements, and emergency response standards. It works jointly with the FRA on railroad hazmat incidents.
An expedited directive issued by the FRA Secretary without the normal rulemaking process when there is an immediate safety threat requiring urgent action. Emergency orders may restrict operations, mandate equipment inspections, or require immediate corrective measures. They are among the most powerful regulatory tools available to the FRA.