Sen City Single Tunnel Portal - High Floor. Removes track gravel in tunnel. Better with some track than others - good with track by Nexusdj.
Instructions - 1) Use DigHole asset to make hole in terrain.
2) Place Portal and attach track and tunnel bore. 3) Cover excess hole with any Retaining Wall, (retainingwall4 by Compudoc, <kuid2:56732:1035:1> is a good match).