Cantilever racks are specifically engineered for storing long, bulky, or irregularly shaped items that do not fit well on standard pallets. The design consists of vertical columns with horizontal arms extending outwards, creating an open and accessible shelf. This structure is ideal for materials like lumber, steel rods, pipes, and sheet goods because it provides unobstructed horizontal space, allowing for easy loading and retrieval with forklifts. These racks are a common storage solution in home centers and industrial warehouses that handle such materials.

A. mobile sliding racks: These high-density systems are designed for archival storage or small parts, not for long, heavy, and bulky items like lumber or steel.

B. drive-in and drive-through racks: These are high-density systems for uniform, palletized loads. They are structurally unsuitable for storing long, non-palletized materials.

D. push-back racks: This is a high-density storage system for pallets operating on a Last-In, First-Out (LIFO) basis and is not designed for long or irregular items.

1. Bartholdi, J. J., & Hackman, S. T. (2019). Warehouse & Distribution Science. Georgia Institute of Technology. Chapter 4, Section 4.1, "Storage media," describes various rack types, noting that cantilever racks are used for storing items like lumber and pipe. (Available via Georgia Tech SCL website).

2. Material Handling Institute (MHI). (n.d.). Racks. MHI Industry Groups - Rack Manufacturers Institute (RMI). The RMI section on the MHI website describes cantilever racks as being "ideal for storing long, bulky, or irregularly-shaped loads such as furniture, lumber, and pipe."

3. Tompkins, J. A., White, J. A., Bozer, Y. A., & Tanchoco, J. M. A. (2010). Facilities Planning (4th ed.). John Wiley & Sons. Chapter 10, "Material Handling," Section 10.5.2, "Storage Equipment," details that cantilever racks are designed specifically for storing long loads such as bars, tubes, and lumber.