Paul Mallory was oriented towards club layouts (and very large home layouts). John Armstrong was oriented towards the folks who had smaller spaces and the attendant tradeoffs between things like curve radii and railroad like operations.
The first edition of Track Planning for Realistic Operations included several examples of how to modify some of the published plans of the day to improve their operating capabilities.
Sure 36" or 48" minimums are nice. But the reality for most of us is that those minimums are either impossible or leave us with a loop of track and little else.
Many of us would do well with talgo trucks and deep flanges. That's how Lionel O27 trains get around a 13" radius curve.
Paul
IRONROOSTERJohn Armstrong was oriented towards the folks who had smaller spaces and the attendant tradeoffs between things like curve radii and railroad like operations. The first edition of Track Planning for Realistic Operations included several examples of how to modify some of the published plans of the day to improve their operating capabilities. Sure 36" or 48" minimums are nice.
I bought John Armstrongs book back in the 1980's and it has been a major help in my designing and building 3 layouts so far. But keep in mind, not only was John Armstong dealing with smaller spaces and "givens and druthers", he was also a product of times when standards were simply oriented around sharper curves.
For example, in his book he refers to 3 major classes of curves by the folloing terms (from memory):
18" Radius - Sharp24" Radius - Conventional30" Radius - Broad
Just my observations but since the mid-late 1980's and after, I have noticed the majority of moderate sized layouts in MR magazine articles have minimum radius curves of 30". Noting that trend, it might be appropriate to update the terms:
18" Radius - very sharp24" Radius - moderately sharp30" Radius - conventional42" Radius - broad
Of course many modelers still have to contend with limited space and use old style sectional track curves such as 18" and 22" radius, but it does limit the rolling stock being run and beyond that, appearances of rolling stock can be impacted as well. There is a great article written by Joe Fugate on that subject in the January 2009 MRH issue.
http://model-railroad-hobbyist.com/mrh2009-01/curve_insights
Some rules of thumb are discussed in the article which point out that the curve ratio is a factor of the length of rolling stock. By way of example, a 40 ft box car, which is 43 scale feet over the coupelrs (5.9 inches). If you multiply that by 2, you get 11.8 inches - so basically a 12 inch curve will allow a 40' box car to track, but just barely. If you go to 3x the length, you get an 18 inch curve for reliable tracking. Those 40' box cars would look less toylike when viewed from the outside of a 24 inch radius curve. See the list below - measure the length of your rolling stock and do the match to see where it falls.
2.0 x Some equipment may track reliably, but 2x is generally considered pushing it.
2.5 x Most equipment will track reliably if everything is of similar length.
3.0 x All equipment should track reliably; coupler performance adequate if altered to allow 50% car width swing.
3.5 x Equipment will look less toy-like when viewed from inside the curve.
4.0 x Equipment will look less toy-like when viewed from outside the curve.
5.0 x Most reliable coupling on curves with body-mounted couplers and near-scale draft gear boxes.
Rio Grande. The Action Road - Focus 1977-1983
riogrande5761I have noticed the majority of moderate sized layouts in MR magazine articles have minimum radius curves of 30". Noting that trend, it might be appropriate to update the terms:
Yeah, maybe if your observations were correct. This is like the situation we have today with cable news - people seek out the news that agrees with their point of view. If you look at the track plan database and do the math like I did, you'll find the median minimum radius for modest layouts is 24".
I do agree that the work done by the Layout Design SIG that Byron mentioned earlier and was the source for the MRH article you quoted is the best advice available today.
I have the right to remain silent. By posting here I have given up that right and accept that anything I say can and will be used as evidence to critique me.
Using transition curves you can get away with a tighter radius.
My observations were correct for me and not meant to contradict any "databases"; I gravitated to articles I found the most inspirational to me personally (e.g. Eric Broomans Utah Belt, David Barrows CM&SF), and many other articles of that caliber) and noticed remarkably consistant pattern of 30 inch minimum radius listed in the layout information tables. It bespoke that quite a few trend setters in the hobby appeared to also be setting some standards in minimums, at least in that class of layout.
Personally I think there are some major advantages to pushing the boundaries if layout design and making curve radii a priority as much as possible. Joe's article mentioned above gives "legs" to it.
A big part of that change in radius classification is the trend to bigger equipment by the prototype. In the 50's even the real railroads didn't have 89 foot articulated auto racks. The trends didn;t follow exactly liek today, but in the 50's there were a lot more people modeling the 1920's and earlier, which had even SMALLER equipment than the then-contemporary 50's railroads. Modern stuff is just HUGE. An RS3 looks small next to an SD70ACE or AC4400CW. Just like a 1910 Consolidation looks small next to a late steam era 4-8-4's.
Since I model the 50's with predominantly 40' box cars (and shorter hoppers), 30" radius curves will be just fine - that's the 5x car length figure. There's a guy posting in the LDSIG and Layout Construction groups on Yahoo who seems to think he needs 48" radius minimum for N SCALE which is just insane - although the style of his postings makes it hard to understand what he's trying to say. Pushing the limits is great but in the end I want to have a workable raillroad and I only have so much space. If I had a hanger to build in? Sure I'd go 60" minimum radius and no turnouts smaller than a #10. I haven't seen a model made yet that REQUIRES those sort of dimensions (in HO). Sure it would look nice, but can I build a practical layout in my basement if I used 60" radius curves? If all I wanted was a giant version of your basic oval, I could do it.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
rrinkerThere's a guy posting in the LDSIG and Layout Construction groups on Yahoo who seems to think he needs 48" radius minimum for N SCALE which is just insane -
And awsome looking if he can get away with it! =p
Pushing the limits is great but in the end I want to have a workable raillroad and I only have so much space. If I had a hanger to build in? Sure I'd go 60" minimum radius and no turnouts smaller than a #10. I haven't seen a model made yet that REQUIRES those sort of dimensions (in HO). Sure it would look nice, but can I build a practical layout in my basement if I used 60" radius curves? If all I wanted was a giant version of your basic oval, I could do it. --Randy
Hence why John Armstrong always did a "givens and druthers". Context is the key here; no air craft hanger? It's common sense that model railroading is all about compromises, although some might be able to kick up the radius a couple of inches without a major change to a track plan.
It is interesting to note that curve radius is probably the one item where the selective compression between model railroads and the prototype is most pronounced. In the prototype, curves below a radius of 870 ft are very rare; that would amount to 10 ft in HO. Taking it to the extreme, the standard curve radius on new high-speed tracks is 4000 m for 300 km/h (186 mph), and up to 7000 m for higher speeds. 4000 m equals around 13,000 ft; in HO, this would give you about 150 ft (feet, not inches).
DrWIn the prototype, curves below a radius of 870 ft are very rare; that would amount to 10 ft in HO.
They have the unfair advantage of not having to turn before hitting a wall.
carl425 DrW In the prototype, curves below a radius of 870 ft are very rare; that would amount to 10 ft in HO. They have the unfair advantage of not having to turn before hitting a wall.
DrW In the prototype, curves below a radius of 870 ft are very rare; that would amount to 10 ft in HO.
The question is not having to turn before you hit the wall, the question is how close do you get to the wall before you start turning.......
Seriously, if one wants to run modern equipment, or if one wants to run passenger cars, something above 30" radius, and preferably above 36" radius, should be considered the minimum for the mainline. And they should be minimums, with any curves that can be larger, being larger for the visual effect.
All curves should have sprial easements, changes in direction less than 45 degrees parabolic curves (two easements back to back, no fixed radius), just like the prototype.
Just my views....
Sheldon
Armstrong covered that well too, with his "coefficient of lurch" (nothing to do with the Addams Family) where he demonstrated that a tighter radius curve with proper easements results in smoother operation than a larger curve without them.
I'm glad that my many of my layout design clients aren't as hung up on some folks on this thread seem to be on specific values for curve radius -- they wouldn’t be building and enjoying their layouts today. The selected minimum radius must serve the layout concept and fit the room. Many folks successfully build a model railroad without an expansive basement at their disposal. Easements help a lot.
The Layout Design SIG’s curve radius rules-of-thumb, which were the basis for the MRH article, are an excellent place to start when making those trade-offs.
Layout Design GalleryLayout Design Special Interest Group
cuyama I'm glad that my many of my layout design clients aren't as hung up on some folks on this thread seem to be on specific values for curve radius -- they wouldn’t be building and enjoying their layouts today. The selected minimum radius must serve the layout concept and fit the room. Many folks successfully build a model railroad without an expansive basement at their disposal. Easements help a lot. The Layout Design SIG’s curve radius rules-of-thumb, which were the basis for the MRH article, are an excellent place to start when making those trade-offs.
The only thing I am hung up on is close coupled passenger cars with working/touching diaphragms.
I really don't run passenger equipment, but am more freight oriented.
Even current production brass models run the gamut from steamers that are compact and specifically designed to operate on 24" radius to those that must have ahem, larger, radii (36" and up). It depends upon what the owner of the layout wants to run. Many brass 2-8-2 and smaller locomotives will negotiate "conventional" radii, depending upon how one chooses to define "conventional".
Do they look better on 30" or 36"? Sure.
Some of us cannot have all the curves that big--easements are your friend, use them.
John
More than 2 weeks since the thread started and the OP is no where to be found. Not even a "thank you I'll check those books out." This is a drive by thread.
Henry
COB Potomac & Northern
Shenandoah Valley
BigDaddyMore than 2 weeks since the thread started and the OP is no where to be found. Not even a "thank you I'll check those books out." This is a drive by thread.
Maybe he decided based on the reply's that he didn't have room for a layout and gave up on the idea. I've seen would-be modelers scared off by the radius snobs before.
carl425 BigDaddy More than 2 weeks since the thread started and the OP is no where to be found. Not even a "thank you I'll check those books out." This is a drive by thread. Maybe he decided based on the reply's that he didn't have room for a layout and gave up on the idea. I've seen would-be modelers scared off by the radius snobs before.
BigDaddy More than 2 weeks since the thread started and the OP is no where to be found. Not even a "thank you I'll check those books out." This is a drive by thread.
Possibly so. And, as someone who sold trains for years, I have seen people build layouts with 18" radius and then get frustrated because their 85' passenger cars will not stay on the track.
When told why they simply gave up and left the hobby.
Using smaller curves is fine, as long as you understand and accept the restrictions you are putting on yourself and the layout.
But if no one has a discussion.....and no one suggests why larger curves might be better.........
ATLANTIC CENTRALBut if no one has a discussion...
You mean like your first post in this thread?
ATLANTIC CENTRALBigger is better......... My choices, 36" minimum mainline, 48" prefered.
carl425 ATLANTIC CENTRAL But if no one has a discussion... You mean like your first post in this thread? ATLANTIC CENTRAL Bigger is better......... My choices, 36" minimum mainline, 48" prefered.
ATLANTIC CENTRAL But if no one has a discussion...
ATLANTIC CENTRAL Bigger is better......... My choices, 36" minimum mainline, 48" prefered.
Yes, hoping the OP mjght say "why?".
And a workable MINIMUM to fit the space doesn't mean all curves need to be that sharp. One thing that is rather boring is long stretches of straight track exactly parallel to the wall and/or fascia. Use that space for some nice extra broad sweeping curves for some scenic variety.
It's modus operandi here in MR forums for people to post a topic with questions or needing help and then nothing but *crickets* after that. I'm pretty used to it after some years now.
PRR8259 I really don't run passenger equipment, but am more freight oriented.
I'm mainly freight oriented but such pesky things as 89' TOFC flat cars and auto racks and 86' auto parts box cars have been very common since the mid-1960's and were very much a part of daily freight operations on many RR's, so you need "decent" curve radii to handle them.
--easements are your friend, use them. John
Always!
rrinker And a workable MINIMUM to fit the space doesn't mean all curves need to be that sharp.
And a workable MINIMUM to fit the space doesn't mean all curves need to be that sharp.
For sure; you can have a minimum radius that may allow all of your equipment to operate reliably, which may not look very nice with longer cars, but you can do things to minimize the appearance or hide some of those locations.
Rob Spangler noted one scene on his layout where there was a turn-back and hid it with a ridge so that under normal viewing conditions, you can't see the sharpest part of the curve. I don't know what the radius was - probably something decent but maybe not visually as good under longer cars.
One thing that is rather boring is long stretches of straight track exactly parallel to the wall and/or fascia.
That is something discussed in a number of MR articles on layout design. I'm not a member of any Layout Design SIG's but I would imagine this is one of a number of design elements discussed. For example, it's better to not run long stretches of straight track perfectly parallel to the edge of the layout.
Use that space for some nice extra broad sweeping curves for some scenic variety. --Randy
John Armstrong mentioned scenic curves in his Track Planning For Realistic Operation - suggesting even though most curves may be so sharp as to be visually unappealing, it's good to include at least one scenic curve which is quite broad and allows the viewer to enjoy trains with longer cars better. I incorporated a 54" curve on one side of my rather small 10x 18' layout for that purpose.
riogrande5761 One thing that is rather boring is long stretches of straight track exactly parallel to the wall and/or fascia. That is something discussed in a number of MR articles on layout design. I'm not a member of any Layout Design SIG's but I would imagine this is one of a number of design elements discussed. For example, it's better to not run long stretches of straight track perfectly parallel to the edge of the layout. Use that space for some nice extra broad sweeping curves for some scenic variety. --Randy John Armstrong mentioned scenic curves in his Track Planning For Realistic Operation - suggesting even though most curves may be so sharp as to be visually unappealing, it's good to include at least one scenic curve which is quite broad and allows the viewer to enjoy trains with longer cars better. I incorporated a 54" curve on one side of my rather small 10x 18' layout for that purpose.
My new layout has several places where long stretches of track run parallel to both the front (fascia) edge and the wall. And several places where it doesn't.
There was a movie several years back about Alfred Hitchcock making Psycho. One character told him that horror movies were rather low class and simplistic, and he replied, "Yeah, but what if somebody really good was to make one?"
I'm not Alfred, but I designed my layout the way I did on purpose. In fact, I broke at least four or five of the Eight Commandments of Good Layout Design, and did so knowingly.
Robert
LINK to SNSR Blog
Following up on my previous post.
First: I'm typing this on my cell phone, so long complicated missives are a bit difficult.
Second: I model N scale, so any numbers bandied about need to be multiplied by 2 so that HOers can relate.
Third: the OP was about HO scale curves, but since the OPer seems to have dropped out and since Atlantic Central wanted to expand the thread to a broader discussion, I'll bite.
Fourth: specific acknowledgement that opinions may vary.
The absolute minimum radius on my layout is 18", and those occur mainly in the yards due to the Peco medium turnouts (estimated to be #6). Most of the curves are in the 24" to 30" range. Several are in the 36" to 48" range. A couple are in the 60" to 90" range. I have one long, broad curve that is 72" radius, but it runs exactly parallel with the fascia. So, do I get points for such a broad curve? Or, do I lose points because it follows the fascia?
My train room is 24' by 25' and the layout footprint is about 18' by 25'. I look at it as the world's largest diorama, with a few kenetic elements tossed in here and there for fun. My main design criteria was to create scenic vistas, and if spectators stand in certain locations around the layout and look in particular directions, they'd see the vistas I intended to create. I will do my best to try to make those scenes as un-boring as I can. Here is a sketch of the layout with the vantage points I wanted to include. There are two #4 viewpoints (Dang!)
ROBERT PETRICKMy new layout has several places where long stretches of track run parallel to both the front (fascia) edge and the wall. And several places where it doesn't. There was a movie several years back about Alfred Hitchcock making Psycho. One character told him that horror movies were rather low class and simplistic, and he replied, "Yeah, but what if somebody really good was to make one?" I'm not Alfred, but I designed my layout the way I did on purpose. In fact, I broke at least four or five of the Eight Commandments of Good Layout Design, and did so knowingly. Robert
Re: parallel to layout fascia - I'm just passing on what layout designers have recommended; if you aren't happy with that design element idea, I'm afraid you'll have to argue that with those folks. Me, I'm just the messenger - don't shoot the messenger!
You don't need to defend your layout - you only need to please yourself ultimately.
As has been suggested, I think the scenic aspect of the layout would benefit from a bit of bend in the long straight parts.
- Douglas
DSchmitt jjdamnit Hello all, Lone Wolf and Santa Fe Here is a list I made up of minimum radius for different type of equipment. Toys = 18” Most scale models = 22” Scale models with accurately detailed fames and coupler pockets = 24” Steam Locomotives = varies up to 30" or more. The quote that 18-inch radii is for toys! Seems to be nay saying to me. Hope this helps. 18" radius was the HO standard for years. Many fine HO layouts have been built with 18" radius. Still bigger is usually better, especially with the newer locomotives and cars which often do not have the design compromizes that were accepted in "the old days".
jjdamnit Hello all, Lone Wolf and Santa Fe Here is a list I made up of minimum radius for different type of equipment. Toys = 18” Most scale models = 22” Scale models with accurately detailed fames and coupler pockets = 24” Steam Locomotives = varies up to 30" or more. The quote that 18-inch radii is for toys! Seems to be nay saying to me. Hope this helps.
Hello all,
Lone Wolf and Santa Fe Here is a list I made up of minimum radius for different type of equipment. Toys = 18” Most scale models = 22” Scale models with accurately detailed fames and coupler pockets = 24” Steam Locomotives = varies up to 30" or more.
The quote that 18-inch radii is for toys! Seems to be nay saying to me.
Hope this helps.
18" radius was the HO standard for years. Many fine HO layouts have been built with 18" radius. Still bigger is usually better, especially with the newer locomotives and cars which often do not have the design compromizes that were accepted in "the old days".
I'm sorry, I didn’t mean 18 inch minimum radius meant that your trains were toys. Rather that 18 inches is the tightest radius you want if you are a “Toy Train Collector,” who operates toy trains from Tyco and other brands which were designed for the toy market.My original layout was Tyco slot cars and trains together. It was a toy train layout. When I started operating scale models I found that too many of them would not run on my 18 inch radius track. Therefore I would not recommend a minimum radius under 22 inches for scale models if you can avoid it. If you know that only shorter cars and four axel locomotives are going to be on a spur then you can go below minimum radius, but I only do that if there is no other choice. If you know you are modeling an era with short locos and short cars then you could use 18 inch curves but if you can use bigger it is always better.
riogrande57615.0 x Most reliable coupling on curves with body-mounted couplers and near-scale draft gear boxes.
If you dont use self centering couplers, you can throw the 5x out the window and couple on a 22" radius or less with a 40' car. FWIW, the prototype does not have self-centering couplers...
Edit: for the most part anyway.
Lone Wolf and Santa FeIf you know you are modeling an era with short locos and short cars then you could use 18 inch curves but if you can use bigger it is always better.
This is not really accurate. Bigger is not always better. You could put a 72" radius minimum in a 13ft wide room...
Also if by design what you are modeling has tight curvature, then there is nothing wrong with 18", or tighter. Google Bronx Terminal. 12.5" (90ft) and 14" (104ft) radius. Works with 36' and 40' HO scale cars.
I dunno....the thread seems to be pretty-much self-sustaining without the O.P.'s input. Perhaps the extended conversation has put him to sleep.
The "best" curve for HO (or any scale) depends on a number of factors, including the size and shape of the space available for the layout, the type of layout (continuous run or point-to-point), the era being modelled (which includes all of the possibilities and restrictions offered by the equipment of that era), the operations which interest the modeller most, etc., etc.My own freelanced road was envisioned as a secondary main line connecting a couple of industrial areas, with perhaps a smaller town or two along the route. I had a very rough sketch (probably overly optimistic about what would fit) for a trackplan.Unfortunately, shortly after starting benchwork construction, I lost about 30% of my layout area to "other uses", and was left with a fairly odd-shaped room. The sketch, now definitely useless, was tossed. The restrictions of that room shape then made establishing a minimum radius the priority, and to that end, I simply cut a bunch of curves out of 3/4" plywood, starting with a 30" minimum and increasing in 2" increments, then layed them, in various configurations, atop the open grid benchwork, noting on a sketch of the room the ones which fit best at each of the room's ten corners. When I look back on the process now, I was as much looking to find the maximum radius I could put in those places, with only a nod to learning what the minimum might be where space was tighter.I then cut more plywood to create all of the required major curves, and once all were loosely in place atop the benchwork, simply connected them with straight-ish track.The mainline minimum did end up at 30", but only on a turning wye in one of the industrial areas. Pretty-well all of the rest is 34" minimum, and there are a couple at 40" and 46", I think, included mainly because they looked good. Very little of the straight-ish track is parallel to either the walls or the aisles.So, for me, curve radii were determined mostly by the shape of the room, and the rest of the layout - scenic features, structures, town placement, etc. - was determined by the curves. I think that my choice of a late '30s era is fairly sympathetic to those parameters, with mostly shorter rolling stock and small to medium size locomotives. Anyone choosing or forced into choosing a smaller minimum radius could make it look less restrictive if they use the restriction as a guide in choosing era, equipment, and their choice of setting, whether it be urban or rural. Sometimes ones dreams of Big Boys or Alleghenys need to be put into perspective if you want a more realistic and enjoyable to operate layout.
Wayne