I'm a life-long railway enthusiast who received my first scanner as a Christmas present, specifically so that I could listen to the railway traffic on the local line.
Living in southern Maryland, there's a line that goes through town, running south to a power plant on the Potomac River in Morgantown, MD, just across the river from Dahlgren, Virginia. I was never really interested in scanners until a fellow enthusiast demonstrated his scanner to me a number of years ago, showing how he could monitor traffic on the line and even in the Washington, DC area, about 30 miles north of my location.
As the trains don't run on any set schedule, hearing the dispatcher give a train clearance on the line alerts me to the coming of a passing train.
I also have the EOT (End Of Train) device frequency programmed so when I hear the data bursts I know that a train is nearby. The EOT device is affixed to the coupler of the last car of the train, in these days of cabooseless operations, and sends the airbrake pressure reading to the cab of the locomotive in a short data burst.
The last 2 years, I've taken a vacation using Amtrak as my mode of travel. Listening to the scanner while on a passenger train can be most enlightening. For example, on my return trip last fall, the train came to a stop in the middle of a field somewhere east of Buffalo. I knew from listening to the scanner that a brake hose had ruptured and that repairs were going to take about 30 minutes about 15 minutes BEFORE the train crew announced to the rest of the passengers the cause of the delay.
As a former Coast Guardsman, I also monitor ship traffic on the Potomac River and Chesapeake Bay.
My interest in scanning eventually led me to obtain my amateur radio license and I'm now an extra class as well as holding a GROL-all because I got a scanner about 22 years ago in order to listen to trains passing through the town where I live.