Centerbeam Flat Car

Prototype Information

The centerbeam flat car revolutionized the transport of bundled building materials when it entered widespread service in the late 1960s and early 1970s. Thrall Car Manufacturing Company pioneered the design, featuring a longitudinal truss or “centerbeam” running down the center of the car. This structural partition acts as a backrest for lumber, plywood, and gypsum board. By securing loads against this center beam, shippers could load and unload the car from both sides simultaneously using forklifts. This system significantly reduced labor costs and turnaround times compared to traditional bulkhead flat cars or boxcars.

Throughout the 1980s and 1990s, the design evolved to maximize efficiency and protect cargo. Manufacturers introduced “risers” on the deck to tilt the load toward the center beam, providing better stability during transit. Later innovations included the “opera window” design, which used oval-shaped cutouts in the center partition to reduce the car’s empty weight without sacrificing strength. Today, these cars are the primary workhorse for the North American timber industry. They allow railroads to move massive quantities of construction supplies in uniform, weather-protected bundles across the continent.