To put it simple I ran out of room. I am operating three main line tracks and one trolley line on a 5 X 10 layout. So I took an idea from a old Lionel dealer layout I saw a while back. The solution was simple go under ground. I am going to have 1/4th of the total track above ground and 3/4th of the track under the table. By making a large S curve I now can even run larger train consist. The large S curve will permit the extra space I need to run a consist of 30 cars without it appearing it is running engine to caboose. Basically the track will lead to a tunnel which will then drop the track below the main level of the layout. The track then will eat up as much space under the table it can. The track then will again reach the upper level through a tunnel making it possible to fit in another main line which will be the longest in regards to operating those long consist that I like.