As a computer professional and engineer I can echo all of the previous comments as being valid and that the universal answer of
it depends absolutely applies. And this before I have even begun my very first and what will likely be very complex multi-year layout build. (more on that later in the post).
Computer Aided Design programs are very powerful, when designed well, and each has a certain learning curve associated with them. There is pain and little progress as you become familiar with the program over weeks or months of working with them. The payout is once you become familiar with them enough to be able to use them the way we all use a word processor like MS Word; you can then do a lot a lot faster... but the
scope of the project is still key.
If you are doing a table top layout, where everything is on one plane, or maybe only one slope up to a bridge and down again, no mater how large the table, you can probably do just fine and get to a solution quicker by drawing it out on paper, doing some rough estimates of the track pieces you need and then building with the track pieces. CAD software there is not worth the effort.
However, if you will have varying levels as well as substantial complexity and are trying to optimize your use of the space you have to fit certain geometric features into it - say reproduce some aspect of a real rail line/station/yard in some way on your layout, THEN there is a huge advantage to using software.
And if you are like me, starting from scratch and intending to do a big build, and thus you need to buy almost all of the track you will use, then it really helps to design out the layout in CAD and have it give you a bill of materials (the parts you will need to buy with part numbers, and the costs) - because then you can plan and budget and order much easier with less purchases and waste.
In my case, I've got the whole bonus room above the garage available, which is about the size of a 2 car garage, with 10 foot ceilings. My intent isn't to fill the room, but I've got a lot of space to work with, but still within the constraints of where the walls, doors, window and closet are located. The conditions I'm working with are:
- substantial sized blank canvas
- size constraints from the walls/windows/doors
- multi-year building plan
- desire to be able to modularize - to allow transport or reconfiguration more easily
- multi-level: 3-4 elevation planes above the table/ground surface, as well as at least 1-2 levels below the table for the shadow stations and yards
- will include helix accents and descents to get up and down within a smaller footprint and not needing long runs
- sets of features and stations from the real world in Germany, as well as seen on other layouts I want to include
- want to integrate a limited Faller Car System component for vehicle traffic on roads that crosses a rail line.
To bring these things together, it is so worth it for me to become familiar with a CAD program to do the work and have it handle the geometry checks, generate parts lists, etc.
I'd not use AutoCAD to draw up a bird house design, but I'd get benefits if I was doing a landscape or building. Similarly, if I was just doing a layout on a 4x8 table top I'd do it by hand/paper, but for what I have planned, I definitely want to use the computer tools.
