In November of 1942 Jack Delano was roaming around the Illinois Central Railroad’s vast hump yard operation in Chicago, Illinois. He spied these towers in various locations, and inquired into their function. These are the retarder operator’s towers.
When a car is sent over a hump, it rolls down into the yard by gravity through a maze of track switches, and is directed into the appropriate track. The speed of the car must be controlled, and mechanical devices (retarders) are used to typically apply pressure to the wheel flanges as they roll by, thereby slowing the car. The retarder operator controls when and where the retarders are applied. The task is to slow the car near it’s destination to prevent it from crashing into other cars. But at the same time, enough momentum must be kept that the car doesn’t stop prematurely, especially if it’s still traversing a switch. These operators control things from these lofty perches.
Imagine climbing or descending that staircase on a cold winter’s day, with snow and ice underfoot!