Well being the engineer that I am here are my phases for builidng the railroad:
1) Measure the space and elevations of the area for the layout
2) Design the layout on the computer using tools that acurately measure distance, track sizes, and elevations
3) Run some test on the track radii and locomotives to make sure that everyting will work.
3) Do a mockup of the layout to make sure all of the assumptions are correct.
4) Pick one point to start the layout and work everyting from that point. (For me that was setting the 4×4 posts for the highest topmost bridge in the layout. I then built the loop next and then contined down towards the lake.
5) Continue building out layout until it is complete.
6) Decide on signals and gates and wherte they should be installed. I have bought samples (1 or 2) and will try them on the layout and then decide what I would like to use.
7) Work on infrastructure that will be below ground for the layout. Wiring, pipes for the waterfall, drains, sprinklers for the planst.
7) Build up the landscaping walls
8) Build up the mountains and other unique features.
9) Fill in with Dirt
10) Build out cities and other non-train areas
11) Add in plants, flowers, and shrubs
12) Develop the Operating plan for the different trains
13) Have fun and play with the locomotives