I have two layouts in the basement, an overhead that runs 100 ft. around the entire bar and rec area, and a much larger table layout.
In this pic, you can see the boxed I beams. No way to connect to the table layout.
Here are four of the five levels on the table layout, which runs through and around old cabinets, the vacuum, a large refrigerator, etc.
The two lower levels are connected, the two upper levels are not.
This ascending ramp looks steep, but, the LCP engine easily pulls 15 cars up it's 12 foot length.
The bump and go trolley line partially hides the water pipe, and doesn't need to be connected. Neither does the other trolley on the right, which used to be connected to the second level.
The makeshift station is the other end of the light blue, 027, trolley line.
A connection between the level 1 and 2, which goes up 6 inches, around the rocket launcher, and back to table level.
I don't mind that the mainlines are mostly unconnected to each other. I like the levels, and if I wanted more of these great trains, I had to build up. Also, to run seven engines plus two trolleys, at the same time, it's better not to worry about trains running into each other. With my basement setup, having to work through three rooms and around all the stuff, prototypical was out of the question. I'm very happy with this toy train layout.
Jerry