Track can have different build styles. This influences the drawing in 2D, but also in 3D.

Select the track first, so the Track tab appears.

Standard #

The track is displayed as-is, both in 2D and 3D.

Hidden #

The track is displayed as a dotted line in 2D. In 3D, it will be hidden, and a tunnel is created if necessary.

Embankment #

In 2D, small lines indicate that the track is on an embankment. In 3D, the ground is shaped as an embankment.

Bridge #

In 2D, trellis is drawn over the bridge. In 3D, the track is put on pillars.