starting from ground up literally

minimium radius wanted?

Three feet is about the limit one can reach comfortably and confidently with any weight. So you could easily do an around the room or table and reach everything.

I have an around the room with center peninsula layout two feet along three walls with three feet along the fourth.  My aisles are 3' and 2' wide.  Visitors keep to the wider aisle.  The space you need to walk around and to entertain guests will determine how much space you have for bump outs. 

The biggest factor is how do you intend to run your trains.  When you can answer this then you can answer Patrick's question plus a lot more.

Jan

i built a 5X9 layout on a platform that i could raise and lower with a boat winch, reinforced some roof trusses in attic over garage,  and worked on it for years, but it really has surpassed its weight load status and have run out of room

this is one of the stick built buidlings that i will move to new layout

probably radius turns 40 ish  with atlas tracks and switches

Around the room on one or two levels will provide max curves and run length. 

Island pike provides the tightest curves and most cramped layput.  Great for a tight urban trolley setting.

When you consider the relatively small building size of 12 X 16 and then reduce those dimensions by the total wall thickness on three walls you are down to  11 X 15.5 or 11.5 X 15.  Then if you further reduce the footprint by the aisle space on three sides for an island pike you have something like 6' X 12' left for a platform.

The 6' width incidently happens to be a nice reach.  For get crawl under access holes unless you are getting younger each year.

Bottom line, the square foot building structure construction price for that table top layout will be very expensive.  6 x 12 = 72.  divide that figure into the addition cost.  An around the wall layout could provide about 120 sq. ft. of layout space.

You mentioned available yard size.  Is this a code issue?  If so consider what I did.

My last location had a limit on square footage of additions so I had all corners built on a 45 degree angle.  We usually do not need corner space anyway.  That gave me 12.5 square feet of extra floor space from each corner.

I  then streached a long elevated "dog house" over the yard for a first and third level passenger station to maximize allowed space.  This permitted an extra 30 square foot of construction for only the grade usage of a 10" sono tube.  The planning committe allowed it because I did not touch more than my allowed footprint. After all, my arguement was, foot prints need to touch the ground other wise no "print".

 The thirty feet of additional suspended structure was doubled because I had two levels of RR inside it.

The thumbnail print below shows it in a better proportion.

Why is it that full size prints are squished??  Do I load it incorrectly?

" I had all corners built on a 45 degree angle.  We usually do not need corner space anyway. "  what a novel idea!~  However that kind of carpentry far FAR exceeds my ability to complete.  It took me ten years to get enough courage to build a garage, and i over built it but wth i live in hurricane country, walls are 2X6 pressure treated on 16" centers and difference in cost of this over conventional un treated 2X4 was a little over 100 bucks

but you have given me more to think about

Just a short thought:  If you go around the walls don't go beyond thirty inches deep.  If you do remember where ever you do go deeper will be where you have the most problems.  And if the bench-work is deeper then 30 inches assure no turnout or any other piece of track is beyond the 30 inch point.  In future years you'll always be glad you did.  

No special carpentry.  Just sketched out a foot print for the permit and gave a copy to 84 lumber.  They had the open trusses made for the roof.  Everything is done cad for the truss work no matter how it may be configured.  It's only a modified hip roof. 

Just snapped a string on the roof sheathing and cut it in.

Use RR-Track software to build your empire first.  Three inches here or there in the train room can make all kinds of difference.  It's also useful for designing lighting.

And to "tag onto" Susan's post.  Put the lights up first!  Plan for backdrops and install prior to everything else.  It makes life much easier.

my father grew up in Ill and lived quite a while in Cicago 20's and 30's  I have a "CAUTION WATCH YOUR STEP" sign from a 1920's ish street car.

what do you all think about (if you build a town) put a street car route in it, and can a street car route cross Atlas track?

can the street car be programed into a computer for stops and starts?

in advance cool and thanks

IN CASE ANYONE WONDERED ABOUT THE NAME 'PELAGO' PELAGO IS THE NAME OF OUR PEARSON VANGUARD SAILBOAT

Boy is Susan ever so right.  I found that my curves exceeded the finished wall surface and I needed an extra 3" of room width. 

Basically just framing out a recess of the 2X4 studs and drywall over cinder block which wound up in a mountain.

Visable along back wall:

Yes you can program a street cat to automatically reverse at each end.

Check out this link:

http://www.trainelectronics.co...oop_dual_coil_relay/

Auto-reverse possibilities....  Simple Auto-reverse Controller

cool

I can't program my cat to do anything apart from sleep on the tracks. 

Put some track cleaner on the cat.  It might as well useful if its rubbing on the rails.

well we have ignition,  concrete footers with cinder block, and a floor.  joices on 16" centers First layer 3/4" 4X8 treated,  second layer 1/3 osb, then cheap carpet, plan on a layer of tar paper between plywood,  starting walls this week

I know you are excited about everything but don't forget to get your lights installed to highlight your layout.  Put them on dimmer switches so you may adjust... 

does not look like much but it is 12X16 and solid, just too darn cold not to do anything 28 degrees F is not fun to work in

Looks nice and level....but shouldn't that be set on permanent footings?

it does not look like it but there are concrete footers and cinder block are mortared in, the stuff in the middle is afterthought and probably will not stay.

3' down and concrete, with cinder block on top,  here in rural NC if it can be lifted up by a fork lift and moved it is considered tax wise different than on a perm slab or perm foundation.

the building that it is attached to has been there for 31 yrs

Oh good.  The middle supports threw me off and I thought all your footings were simply stacked. Hopefully, the weather cooperates soon. Keep us posted with progress pics.  Should be fun.

Rick

where would a model railroad layout be without a NC tobacco barn,  so so common to rural NC,  tobacco or the golden leaf used to be king,  I think that this would not be a difficult stick built project.  there are thousands of these along highways in NC

i sure would not want to do this to make a living. way way too much bending, stooping, whacking head, whacking thumb.  But slowly it progresses,  have three days of rain forecast and probably not much to get done with rain drops.  need to make roof trusses for 12', will use pressure treated ply and 2X4's for ends,  got em so why not?  the first 15" of sheathing is pressure treated ply wood.  When i got into the original building i found some rot, which made me replace the entire floor and some of the sheathing.  Rot was due to my inexperience in doing this, i built the original room 35 years ago,  Completely replaced floor with pressure treated 2X6" lumber and new stud base with pressure treated lumber also,  actually attached a beam to the building and used four hydraulic jacks and raised the whole critter up and tore out old floor completely.   original floor joices were pressure treated 2X6 so they were good.  found a old door in a junk shop paid $5.00 for it and it will be sanded and repainted to go from one room to the other(door was from farmhouse from depression era)