Cargo wagon

A cargo wagon is a rail vehicle used to transport solid items as part of a train. Its main role is moving large volumes of resources and intermediates across a factory, especially where belts would be too slow or too space-intensive. Because wagons hold a large number of item stacks, they are especially effective for bulk logistics between mining outposts, processing areas, and production blocks.

Cargo wagons are also affected by item stack size and crafting yields, which makes the choice of what to transport important. A wagon can hold 2000 ore items such as copper ore or iron ore, but it can hold 4000 processed plates such as copper plates or iron plates. This makes it efficient to process ore near the mines before shipping it by train, since more finished material fits into the same wagon space. The same principle applies when a raw material crafts into fewer, denser products: for example, 5 iron plates can be turned into 1 steel plate, so transporting the result can increase effective throughput by five times.

Beyond train transport, a cargo wagon can be used as a large stationary storage container by placing it on rails and surrounding it with inserters. This setup has several advantages over ordinary chests:

• It can be handled by many more inserters at once than a chest, bypassing the normal limitations of inserter stack size bonuses.
• Items move instantly across the length of the wagon, which can make the setup faster than a transport belt when configured correctly.
• Its inventory slots can be filtered, and its inventory size can be limited.

This makes a wagon useful as a high-throughput buffer, unloading point, or compact temporary storage solution. However, it also has important limitations. It cannot be connected directly to the circuit network. If the wagon is part of a train stopped at a station, its contents can be read from the station, but individual wagons in the same train cannot be distinguished from one another. It also cannot be accessed by logistic robots. In addition, although it has 40 inventory slots, this is less than a steel chest’s 48 slots, and the wagon’s capacity is not affected by quality.

In practice, cargo wagons are strongest when used for bulk logistics and train-based buffering. They are particularly valuable when paired with mining and smelting design that reduces the number of items that must be transported, since train throughput is strongly influenced by how many stacks fit into each wagon.