Maxi IV Double Stack

Prototype Information

Gunderson introduced the Maxi-Stack IV in the late 1990s to handle the shift toward 53-foot domestic containers. Earlier intermodal cars often used five-unit sets, but the heavy weight of larger containers made those designs difficult to manage. Gunderson solved this by creating a shorter, three-unit articulated car. This setup provides extra strength and keeps the car stable under heavy loads. The design allows railroads to stack containers of various sizes, ranging from 20-foot units in the wells to 57-foot units on top.

The Maxi-Stack IV became the standard choice for domestic intermodal transport across North America. It uses a heavy steel frame and shared trucks between the units to save weight and improve tracking around curves. Companies like TTX and BNSF began buying these cars in large numbers starting in 1999. Even though production eventually ended, thousands of these cars still move freight every day. They remain a primary tool for every major railroad because they can carry the heaviest domestic loads with high reliability.