What is the most common type of railway tank car in North America?

• A. High pressure
• B. Cryogenic
• C. Vacuum
• D. Non-pressure, low pressure DOT 111

Answer: (D)

Tank car design centers on how much internal pressure the car is built to handle. Cars fall into non-pressurized or low-pressure, high-pressure, cryogenic, and vacuum-insulated categories. The most common type in North America is the non-pressurized, low-pressure car known as DOT-111. These cars are built to carry a wide range of liquid commodities without the need for pressure containment or special temperature control, making them versatile, cost-effective, and suitable for bulk liquids like gasoline, diesel, and many solvents. That practicality is why this design dominates the rail fleet. The other types exist for specialized needs: high-pressure cars for compressed gases or liquids at higher pressures, cryogenic cars for very low-temperature products, and vacuum-insulated designs for certain temperature-sensitive or low-pressure requirements. But for everyday rail transport of liquids, the non-pressurized DOT-111 car is the standard, and thus the most common.