After an initial review and agreement of my track plan I made a small deposit to show PDM that I am truly interested in their services. They use their design software to calculate material cost and plot the layout incorporating the easements how best to construct and size each section for transporting and assembling the finished product.
Part of next phase includes building a small scale mock-up to aid in visualizing the layout in 3 dimensions. (I get to keep this when the layout is delivered)