Well I found the answer and apparently one track passes underneath the other one. Which is amazing to me because you really don't feel any kind of gradient at all. Looks like I'm not the only one to have wondered this. 
 
http://ask.metafilter.com...-Magical-Subway-DoSiDo

BobF
Do you see any Rubik's cubes laying around?

 
I once solved five mixed up cubes in an average around 39 seconds each as part of a Guiness Book of World Records event back in 1982.  Unfortunately, I wasn't the fastest though...
 
I do like to use alternative solutions however!  The pics below are one of these.  You can't solve then twist to get them either, you have to actually solve the cube in this pattern.
 



 

KenB123
There is a fifth dimension beyond that which is known to man. It is a dimension as vast as space and as timeless as infinity. It is the middle ground between light and shadow, between science and superstition, and it lies between the pit of man's fears and the summit of his knowledge. This is the dimension of imagination. It is an area which we call the Twilight Zone.

I thought this was the Fifth Dimension (I was a DJ from '80 thru '83 for Aquarius Entertainment and had to play this damn song once every hour - man did I get sick of hearing it!).
 

craigb

BobF
Do you see any Rubik's cubes laying around?

 
I once solved five mixed up cubes in an average around 39 seconds each as part of a Guiness Book of World Records event back in 1982.  Unfortunately, I wasn't the fastest though...
 

If interested, there is a guy named Steven Brundage who is competing on the 2016 season of 'Americas Got Talent'. His talent is the Rubik's Cube. With some apparent cube skill, plus some 'magical' moves, he is getting some good attention on the show. One of the more amazing acts on this season's lineup. Search YouTube to see some of his performances.

Yeah , it the underneath thing which I see you already found out  ...
 
Kenny

craigb

BobF
Do you see any Rubik's cubes laying around?

 
I once solved five mixed up cubes in an average around 39 seconds each as part of a Guiness Book of World Records event back in 1982.  Unfortunately, I wasn't the fastest though...
 
I do like to use alternative solutions however!  The pics below are one of these.  You can't solve then twist to get them either, you have to actually solve the cube in this pattern.
 


 
 

Turn the top one upside down and front to back and you get the bottom juan.
 
Takes about 1.5 seconds, no?

bapu

craigb

BobF
Do you see any Rubik's cubes laying around?

 
I once solved five mixed up cubes in an average around 39 seconds each as part of a Guiness Book of World Records event back in 1982.  Unfortunately, I wasn't the fastest though...
 
I do like to use alternative solutions however!  The pics below are one of these.  You can't solve then twist to get them either, you have to actually solve the cube in this pattern.
 


 
 

Turn the top one upside down and front to back and you get the bottom juan.
 
Takes about 1.5 seconds, no?

 
WHOA!!!!!!


 

We were poor so I had one of those knockoff cubes....it had pictures of fruit on it instead of colors.