custom1106 said:
Whats the bare minimum radius I can run in HO? I might have to move to a switcher with some 40 foot rolling stock to have a loop.
The absolute tightest curve you can run is 15", but that is almost never used except for tight sidings. 18" is more the norm for a very tight curve, but that can cause problems with things more than 40' long, including Proto RDCs, almost any SD, pasesenger cars, intermodal cars, etc. If you want to run anything longer than 40', for best results you will want to keep your curves at 22" minimum, No.6 turnouts, which does take some real estate.
Were I in your shoes I would look long and hard at modules, 4x2 sections of trackwork that connect to each other, and consider an "around the walls" layout made up from modules. Set it up at a height of 44-48" off the floor and it won't interefere with things like dressers or beds, but you will have to contend with doorways and closet access. Frankly, I don't think you will be satisfied with anything that can live under a bed. I started on a 4x8, and it was just too limiting, and eventually just plain boring. Going around the room gives you enough running length to make it interesting, and if you have room for a 3'wide section, you can add a yard.
There are other advantage to using modules. They can be torn down for storage, or transported to a gathering of similarly-minded modellers with a local club. If they are built to a common (NMRA) standard, they can be connected together to create a huge layout for club events or displays. And when moving day comes, you don't have to tear down a wall to get your layout on the truck.
Cheers
Scott Fraser
Calgary, Alberta