The
increased volume of coiled steel transportation gave rise to a new purpose-built
freight car. Previously rolls of coiled-steel had generally traveled in specially
equipped gondola cars. In the 1960s a lighter type of car emerged specifically
for hauling coils of steel in an integral trough. The car type gained popularity
and eventually over 17,000 cars were built. Atlas model replicates a 42
design with a distinctive fishbelly side sill.