It lets you travel south towards spawn without having to get off the cart by having a rail above the TVR rail. The minecart simply drops onto TVRs existing rail. The rail above TVRs is high enough where it doesn't interefere with travel on TVR's rail. This required extending the size of the above ground stone structure. I used the same building materials when doing this.
I tried to think of a way to describe it, but in the end I decided to simply build it and post pictures, as that seemed easier then attempting to describe it. Pictures are below:
Again I apologize for doing the work without permission first but it was easier then trying to type what I wanted to do. If this is a problem, I will be more then happy to take it down.