072 Atlas Figure 8

I think this is what you are trying to do:

I used SCARM to generate the above layout.  All of the joints connect within the default tolerances.  The small track pieces I used were 1.75" and 5.5".  Two 1.75" sections were used on either side of the crossover, and two 5.5" and one 1.75" were used to close the straight sections.

With predefined track pieces it is almost 100% guaranteed that you will not close all gaps especially when diagonals are involved.  Sometimes you can force the ends together and the distortion will is spread out over a long section of straights and curves and not be noticeable.

There is a very small gap in the top and bottom straight sections, approximately 0.08" or 1/12th of an inch.  Without cutting two custom pieces you will have to distort the plan.  The best place will be in the O72 half circles.  Construct the crossover complete with forcing the straight sections to connect to the switches. Instead of all 90s the crossover will be something like 91x89x91x89 degrees.  Then add the half circles forcing them to connect in the midpoint.

Jan

Thank you for sharing this!  This is a fantastic document.  I do have spare track and a dremel so I think I can customize sections.  

If you are using Atlas track and turnouts, no cutting should be necessary.