This is a cool idea! I really like the style.
I feel like it was a bit too difficult to gauge exactly how fast the train would be going at a given step.
It felt a bit too easy. I was just creating a path to the end out of normal tracks, and if that was too fast, I would replace one of the tracks and try again.
Also there is a glitch where if you spam place a tile on a single spot, you'll get an infinite amount of them.