I’m not one that pursues a precise trackplan. Instead I pursue a benchwork/deck footprint and then try to confirm that most of what I want will fit. The final track locations get laid out on the finished benchwork/foam.
The week before starting the layout I wanted to know that the space I’d allocated for Farmington would fit lower, middle and upper Farmington yard. To figure that out, put tape on the floor to mark off critical limits of benchwork, then followed with key track elements to representing the prototype track locations.
I’m not going to go into the details of the track. Those who know Farmington can probably make out the SR&RL track and the MEC track and correlate them to the prototype. The MEC track is actual S-scale track with #5 turnouts (which I think would be OK), and the SR&RL track is mocked up with a combination of HOn3 and N-scale track. The scene is about 19 feet long.
I’ve left the tape on the ground to help me to locate the benchwork as I move forward with the construction.
In conclusion, the floor is a good place to test trackplans.