New train tracks appearing outside city limits

Hi everyone,

I noticed something interesting today: On the edges of my regions (Capital City, Green Valley, Sunny Isles, and Limestone Cliffs), new tracks have suddenly appeared outside the city boundaries. In my Capital City, these tracks are even connected to the rails below the mountains.

Do you think we will soon have to connect our own rail networks to these external tracks? Does this hint at a new rail structure or upcoming update?

I’ve attached some screenshots of what I found. Have any of you noticed this in your cities as well?