The Industrial Terrain from GrimDark Terrain is compatible with 6-8 mm Epic Sci-Fi games. It fits perfectly into your terrain. Whether Adeptus Titanicus or other sci-fi tabletop games, it simply fits many settings.The projectile transport for the Land Train has the dimensions 100x39x29mm.you can find the Land Train here: 
 Titanicus Civitas Land Train With Cargo

 Titanicus Civitas Land Train Empty
We have many other terrain models and also Greebles/Bitz on offer. Just have a look around.