About 8-10 years ago, I was on a railfan trip with a buddy. We spent some time in the Pittsburgh area, and went up on the George Westinghouse Bridge over Turtle Creek Valley. From the bridge you look down a couple hundred feet or more into valley with quite a few RR tracks and various connections.
While up there a Union RR train come up a steep grade out of one of the steel plants with a string of flatcars with hot slabs on them - Slabs are pieces of steel about a foot thick, 4-5 feet wide, and 30-40 feet long. These were still hot and smoking. The Union was the US Steel owned RR that served their plants in Pittsburgh area and was also a common carrier.
This train had about 5 SW8s or SW9s just working their hearts out coming up the grade onto the main with about a dozen of theses slab cars. Lots of noise and exhaust. So multiple switchers running MU is a really neat thing.