Before he was hired by a San Diego-based defense contractor, my maternal grandfather worked on the railroads as a pipe-fitter, and he designed and built for me a high-quality Lionel model railroad in his home, before he passed away. It even had those little smoke-generating tablets that you could drop into the smokestack. I was only six years old.
This year, I was curious about whether I could track freight trains in my region or nearby, in real-time, and perhaps more details like what sort of cars were linked in the train, how many locomotives, what sort of freight they were carrying, etc.
After a few fruitless searches for this tracking info, I realized that the same info that would be "recreational" for me would be "operationally valuable" to any domestic terrorist cell or motivated insurrectionist, as well.
Trains derail all the time, we are told, and trains are robbed blind increasingly often, so I am sure there is some sort of illicit/underground tracking that takes place already, but for now, I must content myself with noticing trains using my own eyes and ears. The freight line next door is inhibited from sounding their horns except in emergencies. And thankfully, I find freight-train and light-rail noise to be calming and soothing, even at 3:30am...