It’s been proven that the sense of smell is closely linked to memory. I’ve found, personally, that sound can trigger the floodgates, also.
The train that runs behind my house is a comforting sound to me, though it’s so loud that if I’m outside I can’t carry on a conversation until it passes. The clack and squeal of the wheels and the whistle echoing off the rock embankment and through the woods takes me back to the summers of my youth. I am once more eleven years old, riding the Dahlonega Mine Train at Six Flags Over Georgia. That’s was after standing in a line that snaked back and forth for what seemed like forever with my brothers, only to get almost to the front of the line and have my little brother start crying in fear, refusing to ride. So, we got out of line, delivered him to Mom and Dad, and started all over again. But it was worth it. I never tire of the thrill of a roller coaster, though I have to refrain from those that turn upside down because of my motion sickness tendency..
I have other train memories, real trains and not just pretend ones. But this is one of the happiest.