Which of the following is NOT a transverse structural member of the container?

The tunnel rail is not considered a transverse structural member of the container. Instead, it serves a different purpose, typically related to the design and functionality associated with the container's base.

Transverse structural members are components that run across the width of the container and play a critical role in the integrity and strength of the structure. The front sill, rear header, and crossmember are all transverse members; they provide essential support and maintain the container's shape, ensuring it can withstand loads and stresses during transport.

In contrast, the tunnel rail often refers to elements involved in the bottom structure or to facilitate handling and stacking but does not contribute to the cross-sectional stability of the container in the way that transverse members do. Understanding these distinctions is crucial for correctly identifying components and their functions in container construction.