I used the XTrkCad program to design my layout by first entering the Atlas plan into XTrkCad verbatim, then started massaging it. I started by replacing all the sectional track with flex track, then replaced the turnouts with #5's and #7's since I planned on using code 55 track. I used #7's wherever a mainline train would pass through, and #5's elsewhere.

There were two things about the plan I didn't like, first that the mainline went through the diverging path of a turnout while the straight path led to the engine house, and second there was no diamond crossing (I just find crossings visually interesting). So I removed the offending turnout and instead connected the engine house via a crossing over the outer main to the inner main at that section. I decided I would like more of a yard so I rearranged the team tracks at the front of the layout and removed the industry there to provide my "yard". Lastly, I decided I needed a connection to the outside world so I extended the width of the layout by 6" and added two staging tracks off of the connection to the enginehouse.

I made few changes after the track was laid, but the crossing described above had to be replaced due to functional issues (see the Trackwork section), so it's now a single slip switch.