(PVE) (Pico) Does anyone know why this is being built on my plot?

I came on today to find this track being built. It looks like it is just being started too. I know the main line is near my plot but underground and this doesn't appear to be connected to the main line.

Does anyone know why or who is building this? Is this part of the city plan? If it is I'll let it stay, but I don't like it. My friend whom I share the plot with and I had plans for that area and if they dig down they're going to dig right into my bedroom of lava and water since all our rooms are underground.