In designing a boxcar interior, freight car manufacturers must balance two competing desires. The first is for a smooth interior wall, with nothing to snag, puncture or otherwise damage a load. One modern solution to this was the exterior post car, with its vertical support posts on the outside to allow for an unbroken interior surface. The second desire, however, is for wall-mounted tie-downs or other attachment devices to secure the cargo, to prevent shifting and damage en route. The waffle-side boxcar, introduced in the mid-1970s, successfully satisfied both desires. The waffle-like bumps on the exterior of the car are actually recesses stamped into the inner wall to accommodate load-restraining devices. Thus the car presents a smooth interior wall for load safety, plus the ability to fasten load restraints almost anywhere in the car. This is especially useful for loads that, as truckers would say, weigh out before they cube out - i.e., reach the car's maximum loa
