I think this is an engineering feat! What an idea! I have no enclosed tracks beacuse of limited access, but I didn't think of this. Great job!
It doesn't end there... I can also split the top level from the bottom level. Here is a picture showing just the bottom which contains the train "garage". The tracks in the lower left corner of the picture is the connection to the other module with the large main station. The princip of the track plan is basically a "dogbone". and on this picture you can see that the trains can turn in the loop on the top or go down to the "garage". On the other module the tracks make a big S-turn under the station and comes up in the other end: And then trough the station and in to the helixes in the top level of the first module. On the top it is an end station, but the trains can also turn in a hidden loop right beneath the station: It takes about 8-10 minutes to drive a complete round in normal speed.
