A loaded auto rack car must not be placed behind which type of car?

A loaded auto rack car must not be placed behind open top cars due to safety and stability concerns. Open top cars typically carry bulk materials, and during transit, these materials can shift or become unstable. This movement poses a risk to the auto rack car, which is designed to carry vehicles with specific load and stability requirements.

When an open top car is loaded, the contents may shift or spill over, potentially impacting the auto rack car’s stability. Additionally, if there were to be any sudden movements in the train or changes in loading conditions, the open top car’s unpredictable nature could lead to accidents or damage to the vehicles being transported in the auto rack.

In contrast, placing a loaded auto rack car behind covered hoppers, boxcars, or flatcars does not introduce the same level of risk, as these types of cars typically have more stable load characteristics that are less likely to affect the auto rack car's integrity and safety during transport. Hence, the relationship among different types of cars and the specific loading practices necessitates caution, particularly when it comes to the interaction between loaded auto rack cars and open top cars.