What equipment must each cargo tank vehicle and trailer carry to prevent rolling during loading, unloading, or parking?

The equipment that each cargo tank vehicle and trailer must carry to prevent rolling during loading, unloading, or parking is wheel chocks. Wheel chocks are specifically designed to prevent movement by blocking the wheels of the vehicle or trailer, providing stability and safety during operations.

When loading or unloading propane, it is crucial to ensure that the vehicle remains stationary. Using proper wheel chocks is a reliable measure to prevent unintentional movement that could lead to accidents or spills. They are essential safety tools that are easy to deploy and can effectively secure the vehicle in place.

While other options like safety cones, chock blocks, and braking systems play significant roles in overall vehicle safety, they do not directly fulfill the requirement for preventing rolling during these specific operations in the same effective manner that wheel chocks do. Safety cones help with visibility and directing traffic, braking systems are important for stopping the vehicle in motion, and chock blocks may be used but are less commonly referred to in this context compared to wheel chocks, which are universally recognized for this specific purpose.