These very sturdy and inexpensive plastic portals are ideal to place attractive portals on your model landscape for a few money. The shortest connection between A and B - it is a straight line. In many cases you can realize it only by means of a tunnel. This also applies to real life as well as to model landscapes. It's the best to make a plan showing also the postion of tunnels on a model railway layout. Furthermore you have to decide if you want to have a single track or a double track tunnel section, if you take modern or classic looking portals, if you want to mount catenaries etc. No matter how your tunnel should be - the working steps are always the same.