Track can have different build styles. This influences the drawing in 2D, but also in 3D.
The track is displayed as-is, both in 2D and 3D.
The track is displayed as a dotted line in 2D. In 3D, it will be hidden, and a tunnel is created if necessary.
In 2D, small lines indicate that the track is on an embankment. In 3D, the ground is shaped as an embankment.
In 2D, trellis is drawn over the bridge. In 3D, the track is put on pillars.