Minimum Radius Advice ?

Good plan.

Wish I had that kind of space. Using 72" radius is comparable to 40" radius in H.O. scale. Pretty much anything you'd want to run will run on it. Some say you can use 4" track spacing on curves -- i.e. 72"/76" but overhang from Big Boys could have an unhappy encounter with the underhang from an 85-foot passenger car, so spreading the curves out is probably a good idea (you can sneak them apart in the easements). Looking forward to the plan you're working on.

PLAN AHEAD!!!

Go as large as you can on the radius, don't start off thinking small, especially with the amount of space you have.

Layout down track and run some trains, don't put in any scenery until you're satisfied with the track plan or you'll be spending a good deal of time redoing things.  I bet I've moved track around at least yearly because the track plan didn't do what I thought it should.

I started off just wanting a simple layout so I could run some small freight trains, now that I have over a dozen passenger cars and 1/2 dozen "passenger" engines I find myself running just as much passenger equipment as freight.

Remember to leave plenty of room between mainline and industrial sidings, O scale buildings can take up a good amount of real estate if you get scale buildings and not ones meant for 027 3-rail layouts.  I have a couple of buildings that, because I didn't leave enough room between mainline and siding, I'm looking at the back of the buildings and have to reach over to uncouple cars.

These two circles of sectional track may help you visualize fitting the curves into your space. (see attached) The smaller is a 36" radius(O72) and the larger is a 69" radius (O-138) in GarGraves sectional.

Using the minimum 36" radius for tight curves will still allow for any equipment made as Matt mentioned. Any larger is certainly better.

Once you define your people , mechanical and storage area, the layout area will reveal what the largest radius will be that will fit.

What a great space to have!

With that amount of space, Mainline minumum 120" Dia. min. Industrial and secondary 096" Dia min. Oops I see that you are two rail, I would go bigger than what I wrote.

Clem k

i would go as large as possible but a lot depends on what you are running. i have a couple of westside PRR J's that don't like 96 inch radius. with the large modern cars you are going to run as well as with the space you have i would shoot for 108" radius this will give a fantastic prototypical look to what you are running. i have seen layouts with 72" radius that operate and look great but just like i feel about my hot rods (engine size) bigger is always better! you can look on you tube for videos of the Youngstown Model railroad Association O scale layout and see what modern trains on large radius look like. there are SD  70's & 80's running with auto racks  large tankers and other modern cars. Also double headed N&W Y6B and Class A pulling a hopper train, a Conrail ore train with 40 ore cars as well as several 10 plus car passenger trains. by the way we are having an open house this weekend Sat and Sun from noon till six.

72" will be absolutely fine as your minimum, especially if you are modern era.  I would use as large radius as possible on visible curves but 72" (or even 66" or 60") for turnback curves, staging and hidden track will be OK. If you use superelevation don't make it too high, I went with just under 7/64" (5" prototype) and it is too high, 3" looks much better.

The room size may seem ample at first but utilization will still be key.   Your area is similar to mine in size.   That "generous room" can get real small real soon, trust me! 

I would base my effort on an around the wall plan  with a long peninsula   Working with an around the wall footprint you can have those 108" radius curves in all four corners.

My Big Boy looks silly on my 72" radius curves with that gross overhang.

Most important IMO is to decide what will be the purpose of the RR?  Roundy round display running or some form of point to point prototypical effort?  Roundy round may be a nice goal when you have nothing but it can get old once the trains have been running for a while.

Think purpose.  IMO  An expansive branch line operation with a single medium to small loco pulling 4 to 10 car trains will not diminish the impression of the overall finished project.   Big steam & multi prime units with 12 +/-  80' passenger cares will shrink that sized RR quickly.

Also, consider the birth date on your drivers license and your budget.  Many of us do not consider how long something like this may drag on nor how much $$$$$ it will take.

Lots of senior modelers with half born RRs in this neck of the woods.   Opinion.

You said 72" minimum.  That works, and Jim's advice above is on point, right down to the superelevation.  The 72" should be for industrial sidings and freight only lines.

My biggest loop is 74", and it gives 80" Northerns and articulated coaches fits.  The superelevation looks great, but as Jim says, next time I am going to cut it in half.

Moonman posted:

These two circles of sectional track may help you visualize fitting the curves into your space. (see attached) The smaller is a 36" radius(O72) and the larger is a 69" radius (O-138) in GarGraves sectional.

Using the minimum 36" radius for tight curves will still allow for any equipment made as Matt mentioned. Any larger is certainly better.

Once you define your people , mechanical and storage area, the layout area will reveal what the largest radius will be that will fit.

What a great space to have!

Thanks, but I was referring to 72" radius a opposed to diameter. I had designed an outdoor layout for the back yard with 120" radius (O-240/20-foot diameter) but that idea was quickly killed by the "Secretary of the Interior". I think it had something to do with my planned destruction of a flower bed and the viaduct over part of the pool. Eight to ten foot radius curves would look awesome and would allow for closer spacing on curves.

Thanks for your input!  Great ideas as well a thoughts for me to think about going forward.  Part of my concern has been that even though the room is large when I start drawing it in third planet I can see the room shrinking fast.  I will put some ideas up soon from what I've done with 3rd planet so far.  I plan on modeling NS from Norfolk VA to Norton Va.  So I'm leaning toward a point to point layout with reversing loop on each end.  Thanks again for the comments! Forums are new for me but I can see that there is a lot of good information and ideas from experience out there.

Here are a couple of ideas I've been playing around with so far using 72" minimum Radius.  I do like the sound of the larger radius but I struggle to see how I can use them and maintain a walk around layout without ducking under.

Track spacing on curves can be a job, use at least 5 inches between curves if you have large engines and maybe more if you run articulated steam engines as the tender's step might hit the wheels of the steam engine. 

I have a 4-8-4 MTH T-1 and it hit some of my track side scenery so I had to move the scenery or get it moved by my T-1 steam engine.

Try a test run at very slow speeds with both engines that you want to go around the curves and see what happens, you may need more spacing then you think.

Lee Fritz

I use 65 to 72 inch radius  on my mainlines with 7.5 atlas two rail turnouts. Anything smaller looks kinda cheesy with scale equipment. I have an around the room layout, about 15ft X 26 ft, but am now incorporating a wye for locomotives and a servicing terminal in a center island.

Good luck

Your plan #1 should be discarded because the mainline jumps from one aisle to another aisle.  You want to follow your train without interruption.  Plan #2 shows promise and can be developed into a workable plan.  After the mainline is determined, you can add a branch which ends in a stub yard and will require some switching before returning to wherever.

Tom Tee is correct.  You should print out NMRA Standard S-8 and keep it handy.  It will save a lot of grief later on.  I widened the standard to 4 3/8" on curves during the easement.  It was easy to make a template from Masonite and use it to draw the appropriate lines on the subroadbed.

If you must have a duck-under, make it a nod-under.  A nod-under is a track that  is high enough off the floor that you need to just nod your head to one side to clear it.  I seriously considered a nod-under until I moved to my current house and the basement under it that didn't require it.

Good luck.

Ed

As Ed said, IME, avoid duck unders.  On my last layout I copied Cheery Valley RR and did a step down.  Four 7" risers to go down, walk upright for three feet, then four 7" risers  back up.  This time many  years older, no step downs, no duck unders.  Don't miss them at all. 

Agree with Tom Tee - avoid duck unders.  Lift ups or swing out sections  work well - if carefully designed and built.  They will enable you to use the full perimeter of the room to best advantage.  

Ed Rappe

Given mine and many others experiences a duck-under eventually becomes a pain.

Design it out  by making the layout a folded dogbone or make a lifting or swinging section for entry/exit.

Here are some photos of my lift section which enabled me to go around the perimeter of a 36' wide room without a duck under.  In a later post I'll lay out the reasons I went with under 72" minimum radius curves  and variable track spacing (under 4" on straights). 

Selecting design parameters such as aisle width, minimum radius, turnout size, and base table height entails making some very interesting trade offs between operational interest, route miles, grades, viewing perspectives,  human access/passage, and maintenance.  In making those determinations IMO it should start with putting down on paper your space  and resource (money AND time) limitations followed by a clear assessment of the type of railroad you'd like to run.  Noted layout designer John Armstrong's termed these "givens and druthers".   If you are at all interested in something other than loop running get yourself a copy of John's Creative Layout Design for Prototype Operations -  Rather than giving you fixed prescriptions (like 72"r) that serve to be potentially overly restrictive constraints, it will open your mind to what compromises you may want to consider to pack more operation in your available space.  

One great  choice you've already made is to use a great layout design tool like 3rd Planit .  I found it to be very handy in iterating my layout design -  before cutting lumber. 

Ed Rappe

Keystoned Ed posted:

Here are some photos of my lift section which enabled me to go around the perimeter of a 36' wide room without a duck under.  In a later post I'll lay out the reasons I went with under 72" minimum radius curves  and variable track spacing (under 4" on straights). 

Selecting design parameters such as aisle width, minimum radius, turnout size, and base table height entails making some very interesting trade offs between operational interest, route miles, grades, viewing perspectives,  human access/passage, and maintenance.  In making those determinations IMO it should start with putting down on paper your space  and resource (money AND time) limitations followed by a clear assessment of the type of railroad you'd like to run.  Noted layout designer John Armstrong's termed these "givens and druthers".   If you are at all interested in something other than loop running get yourself a copy of John's Creative Layout Design for Prototype Operations -  Rather than giving you fixed prescriptions (like 72"r) that serve to be potentially overly restrictive constraints, it will open your mind to what compromises you may want to consider to pack more operation in your available space.  

 

One great  choice you've already made is to use a great layout design tool like 3rd Planit .  I found it to be very handy in iterating my layout design -  before cutting lumber. 

Ed Rappe

Ed,

Could you please tell me where you got those large dark-colored brackets in these recent photos that you used to mount your layout to the wall? I don’t remember seeing any brackets that large at the Home Depot or Menards, in town.

Thanks,

Naveen Rajan

Hi Ed,

Looks Awesome.   In a previous life (back when I modeled in HO scale) I was a "S.P.F." (Slobbering Pennsy Freak) and I absolutely LOVE the Pennsylvania Railroad Theme.   Today I model in O Scale and I favor the Conrail/Norfolk Southern Railroads (PRR Region of course) and my new layout will be an Around-The-Room design.  I will require 2 Lift-Up sections similar to yours as well .  That being said, could you please impart the construction of your lift-up section and, perhaps a list of materials including the type of hinges used and (I know I'm pressing my luck here a bit) maybe a couple drawings and/or sketches.  Any help will be appreciated and thank you in advance.

Chief Bob (Retired)

Keystoned Ed posted:

Here are some photos of my lift section which enabled me to go around the perimeter of a 36' wide room without a duck under.  In a later post I'll lay out the reasons I went with under 72" minimum radius curves  and variable track spacing (under 4" on straights). 

Selecting design parameters such as aisle width, minimum radius, turnout size, and base table height entails making some very interesting trade offs between operational interest, route miles, grades, viewing perspectives,  human access/passage, and maintenance.  In making those determinations IMO it should start with putting down on paper your space  and resource (money AND time) limitations followed by a clear assessment of the type of railroad you'd like to run.  Noted layout designer John Armstrong's termed these "givens and druthers".   If you are at all interested in something other than loop running get yourself a copy of John's Creative Layout Design for Prototype Operations -  Rather than giving you fixed prescriptions (like 72"r) that serve to be potentially overly restrictive constraints, it will open your mind to what compromises you may want to consider to pack more operation in your available space.  

 

One great  choice you've already made is to use a great layout design tool like 3rd Planit .  I found it to be very handy in iterating my layout design -  before cutting lumber. 

Ed Rappe

Well said, Mr. Rappe.

There is too much tactical work going on. Now is the time for some strategic planning. You have referenced the source of the process very accurately.

Scottie814, step back and take a breath. You have a wonderful space and have chosen a railroad and further defined a route of the railroad to model. Now is the time to continue that process in defining your "givens".

When you have determined more of that detail the layout will reveal itself to you.

Again, kudos to Ed for bringing the discussion back to where it should be at this point.  

 

 

Ed,

Very impressive!  Even more the photos help with visualization of size and widths of layouts against the wall.  I do have the John Armstrong book already and will go back and study some more.  I would like to be able to do some switching and prototypical operation for myself, but would also like to find a a common ground in the layout to allow my grandchildren the ability to run the trains on a continuous route.  So I will continue to process everyones comments which have been very helpful in planning thus far, and see how the layout will reveal itself.  

On an additional question have any of you used the fast track jigs for mainline construction?  I definitely plan on using there fixture jigs for the switches, but just don't see a lot of information from other modelers on using the mainline jigs.  Most go with hand laid or flex.  

Thanks

Scott Thompson

Scott - For turnouts in visible areas I hand laid mine with Lew Cross's Right-O Way castings (points, frogs, guard rails).  For the few special  long curved turnouts I filed my points the old fashion way in a vise.  In hidden areas I used AtlasO 7.5's - something I wouldn't recommend.  They are expensive, don't look like US prototypes, have occasional electrical issues with feeds & gaps, and have weak throw bars.  I didn't use curve templates as I use a wide variety of radiuses depending on location.  Generally I used a pencil on a trammel arm swung off an old camera tripod to draw the tie edge lines lines to lay the flex track to .  Visible curves were eased (most superelevated) using the simple  flexible stick method in John Armstrong's book.

Naveen -   In two areas of the railroad where layout widths are relatively narrow  I used angled support braces rather than legs to eliminate issues with people kicking the legs as they pass one another in an aisle.  In other areas around the railroad the legs are inset 6" for the same reason.  In the shelf areas I screwed the 1x4 box grid frame to the wall at stud locations.  I made the angle bracket supports with 1x2 lumber.  The vertical member of the bracket is screwed to the wall at a stud.  The diagonal member was glued and screwed to the vertical member at the base and screwed to a grid cross member at the top.  Today a chop saw makes building benchwork much easier (and precise) than back in the days when I used hand held power saws. 

Chief Bob:   I'll start a new thread on how I built the lift section.  Hopefully others will chime in with their approaches and lessons learned. It might be a couple of days as I have to run off to pull a shift running our club's modular Lionel layout at a local library. 

Ed Rappe

Hello Again Ed,

Thank you for the reply.  I'll keep an eye out for that Lift Section Thread.  If possible, please email me and bring it to my attention so I don't miss it.  Enjoy your day at the club!

Chief Bob (Retired)

Keystoned Ed posted:

Scott - For turnouts in visible areas I hand laid mine with Lew Cross's Right-O Way castings (points, frogs, guard rails).  For the few special  long curved turnouts I filed my points the old fashion way in a vise.  In hidden areas I used AtlasO 7.5's - something I wouldn't recommend.  They are expensive, don't look like US prototypes, have occasional electrical issues with feeds & gaps, and have weak throw bars.  I didn't use curve templates as I use a wide variety of radiuses depending on location.  Generally I used a pencil on a trammel arm swung off an old camera tripod to draw the tie edge lines lines to lay the flex track to .  Visible curves were eased (most superelevated) using the simple  flexible stick method in John Armstrong's book.

Naveen -   In two areas of the railroad where layout widths are relatively narrow  I used angled support braces rather than legs to eliminate issues with people kicking the legs as they pass one another in an aisle.  In other areas around the railroad the legs are inset 6" for the same reason.  In the shelf areas I screwed the 1x4 box grid frame to the wall at stud locations.  I made the angle bracket supports with 1x2 lumber.  The vertical member of the bracket is screwed to the wall at a stud.  The diagonal member was glued and screwed to the vertical member at the base and screwed to a grid cross member at the top.  Today a chop saw makes building benchwork much easier (and precise) than back in the days when I used hand held power saws. 

Chief Bob:   I'll start a new thread on how I built the lift section.  Hopefully others will chime in with their approaches and lessons learned. It might be a couple of days as I have to run off to pull a shift running our club's modular Lionel layout at a local library. 

Ed Rappe

 

 

Ed,

Thanks for your explanation of those brackets. They look so perfect, like the metal shelf brackets, just bigger & I wouldn’t have guessed that you made them out of wood. When I saw them in one of your earlier posts, I went to Home Depot & Menards but the largest I could find were 20” X 13”.

Naveen Rajan

Scottie814 posted:

Finally have a building for my O scale layout, 54' x 34' clear span.  Looking for thoughts on minimum mainline radius.  I'm thinking 72".  I will be modeling modern era with Double stacks, mixed freight and of course and amtrak making a run as well. In planning its been hard to grasp the size difference coming from an HO layout in the basement with minimum 28" Radius up to 36" Radius. Any thoughts and experience would be appreciated.  

Use at least 96 diameter!  Larger where you can.  I too have a huge area.  Went with 72 because that's the recommended minimum for O scale I've heard since the 70s.  Now with double-stacks and auto carriers you can see the outer rail as these long cars, including Amtrak Superliners, sweep through the curves.  When these same cars reach my 96 curves they look "correct."  That is centered over the rails.  The best advice has been used countless times:

Use the biggest curves/turnouts you can where you can.

Yeah, but 96" diameter is 48" radius, and very few folks with passenger train models think an 80 footer looks good on that radius.

the OP proposed 72" minimum radius, and I think he was on the right track.

I have a series of test loops at 54" above the deck and a duck- under with a removable section.  I haven't removed the section in over a decade.

Unless he meant a 96" radius....?

We have to assume he meant diameter, since the post he copied speaks of radius, and he clearly states diameter.  He, of course, is the only one who can tell us different.

I've got a drop-down section that's about 37" long, but the layout is only 36" high so when I drop it down it sits not quite 1/2 way into the walk-thru.  It works fine I just have to be careful not to stub my toe or knock it out of alignment when I walk thru.  I often leave it up and crawl under it, but those days are quickly coming to an end (arthritis).

Fellow forumite Gilly has posted photos of his rollout section which looks very sturdy and seems to work very well, you might want to do a search for that.

Let me refine the old planning concept of circles and squares that was intended with my earlier post. You need a lounge, CTC, workshop, etc, so what space is left for track?

Here are 108r\216d circles and a 72r\144d circle with some squares. This shows that 108 in the corners(as Tom Tee suggested) will work nicely. I don't think you'll be able to use 108r for the peninsula's.

Move the circles around of various sizes and take the arcs that you need. Fill-in in between.

IME. The higher the layout the less any over hang becomes apparent.  90 degree corners can easily absorb wide radius.  180 degree or more of right a way curvature flat out rob you of real estate. 

Shield any view of articulateds showing their excessive boiler overhand.  That is something never seen on any right of way location.

Any exposed peninsula reveals the  grin between long cars on the viewing side of the track.

If you use full length spiral easements it will beautify any curve.  A sweeping cosmetic curve in place of an otherwise long tangent ROW  can draw attention away from somewhat obscured tight curves.

Any peninsula needs a hidden minimum curve to be reasonable in fitting into a residential setting.  If you could sneak at least 90 degrees of a 72" (or less) radius into a peninsula mountain or plateau that can help keep aisle space somewhat reasonable.  Opinion

I've working on some ideas for the layout after reading these posts and looking back at John Armstrongs book some more.  Minimum radius is 72".  I've run a couple of 12 car trains around on it with 3rd planet and feel like passing/ siding tracks will be adequate.  Seems to give me some point to point capabilities as well as a continuous run if desired. Thought I would post a picture of where i'm at so far and see if someone sees anything that sticks them as a problem.  I appreciate all of the comments so far in this planning process.    

That looks good. Do you have your cities designated? You have a few hours in that.

My only thought is some that you may have squeezed the people space. If the sidings at 8 o'clock aren't something major, like Norfolk Port, then I would recover that to have 9' for a lounge area.

Thanks Carl, yes I do have the cities designated.  I added them to the drawing to give an idea of the point to point operation.  You make a good point on the people space.  I'm sure I'll revisit the drawing many more times in the coming days.  I'm slowly trying to add sidings and thinking about what each city will  have. Like others have said the planning is as much the hobby as the construction.   

I suppose it's the room perspective that I don't have. Where's the entry?

I only mentioned a larger "lounge" area because with the wonderful layout and building, guests(group visits perhaps, school kids, senior groups and train guys coming over for good times), it seems as important as any other element. Could just be me.

I went and looked at rr maps back at the start when you told us of the route. I was thinking in terms of the terrain change from sea level to Roanoke and then to Norton, Va. How would be the ends be arranged to best present that rise when entering the building and then when viewing the layout from around it.

I think adding terrain objects and viewing in 3D may assist in finalizing the city locations. Is it want you want see when entering the train building? You know what is said about first impressions.

Elliston was an important city as an interchange, wasn't it? I always like viewing an element like that on a layout even if it's simplified from the actual area. Crossovers, a few switches, control tower(s), an engine service area, holding spurs, warehouse buildings. The track maze can be intriguing.

I also like to primarily run right or counter-clockwise for some reason.

It's a lot of miles of track to pick from with too many elements to choose from. You are making great progress.

PS. I took the liberty of resizing the rack plan photo. Old eyes.

Scottie814 posted:

Finally have a building for my O scale layout, 54' x 34' clear span.  Looking for thoughts on minimum mainline radius.  I'm thinking 72".  I will be modeling modern era with Double stacks, mixed freight and of course and amtrak making a run as well. In planning its been hard to grasp the size difference coming from an HO layout in the basement with minimum 28" Radius up to 36" Radius. Any thoughts and experience would be appreciated.  

I started exactly the same as you HO to O.  For years I had heard that 72 was the "minimum" for the big stuff.  That isn't true anymore because manufacturers make long equipment that will go around a 54 diameter curve.  BUT it looks stupid.  

I used 72 as a minimum on my line that covers a basement.  Fortunately only about 33% of my main line has 72 diameter the rest is 89s and 96s.  If I had to do it again I would use 96 as the bare bone minimum for the main line!  Why?  Because of the toy-like appearance of a Superliner or autocarrier passing through a 72 curve.

Think about it for a second.  In HO the minimum "broad" curve is 30 radius.  That means in O in would be 60 radius or a 120 diameter curve.  A 10 foot circle!  I know that is a lot of space!  Look how great the longer HO equipment passes through those 30+ RADIUS curves!  I wish now I would have used the 96 as minimum (that would be 48 RADIUS) in HO and up to and as much as 120 diameter ever where I could fit it especially in the corners.

YOU have a great amount of space!!!  like me.  Be much smarter than me and plan a main line that will boast a minimum diameter of 120 or larger everywhere!  Then you can run a secondary line and do whatever.  It would be a major undertaking for me but one day I may begin a major project and change my 72s up to 96s!