What is the system called where refrigerated trucks are loaded onto railcars?

The correct term for the system where refrigerated trucks are loaded onto railcars is known as "piggyback." This method allows for the efficient transport of goods by utilizing both truck and rail transport in a seamless manner.

In this system, transport containers, such as refrigerated trailers (referred to as reefers), are loaded onto flatbed railcars. This process takes advantage of the cost-effectiveness and capacity of rail transportation while maintaining the truck's temperature-controlled environment for perishable goods. The piggyback approach optimizes logistics by reducing the overall transportation time and cost for shippers as it minimizes the need for handling the cargo multiple times.

The other choices, while related to transportation and logistics, do not accurately describe the process of loading refrigerated trucks onto railcars. Double-decking refers to stacking two levels of freight containers within a transport system, reefer handling is a broader term that encompasses the management of refrigerated transport but does not specifically refer to the loading onto railcars, and freight forwarding is the process of arranging the shipment of goods which does not specifically involve the loading of trucks onto trains.