Several variations of the flatcar have been developed; two are most useful: the depressed-center and the
well-hole. Both of these have the principal advantage of providing additional overhead clearance for freight or
equipment that cannot be carried on the standard flatcar. The depressed-center flatcar has a portion of the floor
between the trucks depressed, as shown at the bottom of figure 1.1. Well-hole flatcars also have a portion of the
floor depressed, but the depressed portion has enclosed sides.
1.3. ENCLOSED CAR
Cars that completely, or nearly, enclose the freight they are carrying have many variations in their
superstructures. They all, however, have roofs, sides, ends, and doors, and protect their contents from the
weather. Of the different types of enclosed cars, the boxcar, the refrigerator and heater car, and the stock car are
the most common.
a. Boxcar. Until recently, the boxcar was the most widely used of all freight equipment; however, it is
becoming secondary in usefulness to the flatcar. For example, automobiles were formerly transported in
boxcars; now the current trend is to use flatcars with double- and triple-deck superstructures to transport them.
More and more commodities are being shipped in prepackaged, weatherproof containers that are well suited for
the flatcar or for trailers that are carried piggyback on flatcars. As a result, the boxcar is losing some of its
popularity. Although the dimensions of boxcars vary, most of those used in the United States have interior
lengths ranging from 40 feet 6 inches to 53 feet 6 inches. Side doors on these cars are at least 10 feet wide. A
typical boxcar is shown in figure 1.2.
Figure 1.2. Typical Boxcar.