Large curved tube (266 m radius) used to join two modern stations or lunar bases (13,5 m in diameter and 424 m long). The reinforced concrete door and the 10 first meter of the tube are straight and the curve begins just after it for 380 m. With this tube you may join two domes at 90° and with 2 joined curved tubes you may turn back. You may join many tubes. It is better in surveyor to put tracks (two tracks if you want or a road) and catenaries or maglev before and the tube after it. I will multiply objects for this kind of stations and you can do it. See for more objects http://trainz-fr.blogspot.com