I had bought an HO-scale FP45, a locomotive that belonged on a massive club-sized pike complete with wide, graceful curves that it could easily traverse.
The problem was that, with money burning a hole in my pocket, coupled with the fact the Milwaukee is one of my favorite railroads, I bought that engine without so much as a thought to whether or not it could traverse the tiny layout I had at home!
What should have looked for instead was a small switch engine, or a locomotive of the “GP” series by EMD –that is, small four-axle units like, say, a GP38-2, or an F-unit like an F-7. Not something gargantuan as that FP45.
Moral of the story: if you have a tiny layout, “Big Boy” steam engines, diesels like that Milwaukee FP45, and many, many others are not fit for it. Look for something colorful, but smaller, like one of the engines listed above, and only buy a bigger engine if you are, say, a model railroad club member or have a buddy with a layout massive enough to accommodate it whenever you are over taking part in running trains on it.