Help With Layout

[Anonymous]

I am working on installing a train shelf in my sons room so that his O scale train can run around his room. I am trying to calculate the realtrax pieces that i need to make it happen.

Question one, When one is talking about 0 -42 for example. what is this measurement. Is it the diameter of a circle? Radius of a circle? what is the outside measurement of an O-42 circle of track (outside edge to outside edge. ) I will be using realtrax.

Question two, Has anyone done this and what issues do i need to consider that I may be missing?

Thanks for any help you can give

[daan]

Hi Bosgood,
There are designing softwares for these things. The 042 referres to the outer diameter of the tracks, so the circle is 42 inches in diameter. I'm not sure if it's measured from the outside or the middle rail though. Keep in mind some track clearance to the nearby walls and the space between can be "filled" with straight ones. If you could find some room for a few switches and some extra track on a shelf somewhere, the layout will be more enjoyable over the long time.

[Anonymous]

Thanks Daan,

I was reluctant to plan a switch at 7 feet up for fear of derailment. We are going to do a permanent layout in the basement when he is a little older. (5 now)

I think i have the track calculated now that i know that 42 is the outside measurement. What is the best way or place to acquire this quantitiy of track? The room is 10 X 14 and if i buy it at the store down the street it is pretty expensive.

[lionelsoni]

Since it will be 7 feet up, you won't be able to see the track anyway. You might as well use the simplest and probably cheapest track, O27 profile. A variety of radii are available:

O27 12.5"
O34 15.75" (Marx)
O42 20.25"
O54 26.375"
O72 35.25"

These are the radius to the center rail. The overall diameter is twice this, plus the 2-inch length of the ties. The nominal size is the approximate overall diameter.

You can get tangent (straight) track in 36" lengths from K-Line and 4-section lengths (about 35 3/8") from Lionel.

[Anonymous]

Thanks Bob,

So what you are telling me is that I dont need MTH track for MTH train. I suppose i could or should have known that but I am an admitted newbie. I alrealy have 027 corners I could use, but was going to opt for o42 to make a more gentle turn, again to avoid derailment in a tight corner. (and to accomodate longer engines when he gets some.)

So can you mix mth track with k-line or lionel on the same layout?

QUOTE:
"These are the radius to the center rail. The overall diameter is twice this, plus the 2-inch length of the ties. The nominal size is the approximate overall diameter."

Thanks for this information that will help a lot!

We are planning to go to a train show on saturday. Is this generally a good venue to get good deals?

[lionelsoni]

There are a number of newer types of track with plastic roadbeds or ties and various ways to connect the sections together. I don't use any of them, so I will leave it to others to say which can be connected easily to which.

The traditional track is "tubular". The rails are tin-plated sheet steel folded into an approximation of a rail, but with a circular cross section for the railhead. They connect with pins which are crimped into one section and fit by friction into the other. This track comes in two rail profiles. The larger one is called O31, O32 sometimes, or simply O.
The radius to the center rail is about 14 1/8". But curves are available in various larger radii. The smaller rail profile is called O27 and is, as I indcated, also available in various curvatures.

It is possible to connect O27 and O31, but not easy because of the different rail heights and railhead diameters. Shimming and rail reshaping are obviously involved.

The gauge of all these kinds of track is the same, 1 1/4". Some trains cannot make it around sharp corners and are limited to the larger radii. Some also bump into the switch machines on the shorter-radius switches; but that is not a problem for you.

Do you know about magnetraction? Lionel, especially in the postwar era, magnetized the wheels of locomotives so that they would grip the steel track better. This allowed them to pull more and made them harder to derail. If you don't have a magnetraction locomotive now, you might want one in the future. Then you would want to have steel rails, not the other metals often used in modern track.

Consider using spiral curves in the corners. Here is a topic that will explain that:
http://www.trains.com/community/forum/topic.asp?page=-1&TOPIC_ID=24916&REPLY_ID=243623#243623

Train shows are a good place to get track, both new and used. They and Ebay are about the only way to get O34, which I find very useful. Stay away from the really rusty stuff.

[Anonymous]

Wow thats a lot of informaion. I see that my basic assumption of what 027 and 031 means is flawed. I thought that referred to the radii of the track. Ok now that i understand what that means.

I do not know about magnetraction (well now I do). The train we have is an MTH PA RR set my son got for Christmas last year.

How will I know what the track we have is. Will it say on the track or the box? It is realtrax that came with the set. I was going to use as much of that as possibel and buy the balance of what is needed.

Thanks for all the help!

[Anonymous]

Bob,

Wow that discusson on Spiral curves was very interesting, and sounds like it may indeed be what I want to do. Once I decide what track I am going to get I will have to figure out how to do that and end up with total of 90% turns in the corners of the room.

[lionelsoni]

You're welcome. Your understanding of O27 and O31 isn't flawed. It's the terminology that is flawed. O27 and O31 do refer to the diameter of a circle of track, to the outside ends of the ties; but these terms are also used, in a confusing way, to refer to the rail profile that Lionel originally used. So now, for example, you can talk about O42 curves of O27 or O31 track.

You wouldn't think there would be two track systems so similar yet incompatible made by the same manufacturer. Lionel bought the Ives company around 1930. From then on they called their original track "O" and the track type that Ives had been using "O27". They generally treated O27 as an economy line of trains; but many train pieces were identical between the two lines, differing only in the model number. The terms "O31" and "O32" are of more recent origin and refer to what Lionel called "O", whose outside diameter is somewhere between those two measurements.

[Buckeye Riveter]

Now that the electrical engineer has had his say about sprials curves (and he did a fine job with the mathamatics) , it is time for the civil engineer and surveyor to give his [2c]

In high-speed orperation for railroads or highways over an alignment on which the curves are circular arcs, an abrupt change is required at the P.C. (point of curvature.) and P.T. (point of tangency) It is obviously not desired to make this change abrutly. Smooth and safe operation of the railroad and highway curves require a gradual transition between the uniform operating conditions on the tanget and the different operating conditions on circular curves.

The ten chord spiral used by the American Railroads is an approximation of the spiral equation. The railroads have been doing this since the early 1900.

Now IMHO, a model doesn't need easement curves for operation as does the real railroads. The model needs them to for a great look aAnd since, Bosgood said he was going to be putting his track 7 ft. above the floor, not only are you not going to get a real good look at the track, but an easement curve would be hard to justify.

Bosgood, with your train that high off the ground, I would not be running it at a high speed unless I had "sideboards" to catch the derailed engine or car. Some people have made the sideboards of flexiglass.

BTW, staking out sprial curves in the field is not easy, especially if there is a mountain or dense woods in the way.

More information can be found about the geometrics of curves for railroads (and highways) in the bible of route surveying, Route Surveying and Design by Meyer. And, oh BTW, a highway curve is based on the length of the arc and a railroad curve is based on the length of the chord. [:)]

[spankybird]

AS long as the other two Engineers have given there [2c] you might as well have a Design Engineer give his.

They won’t let me blow the whistle at work

[:(]


tom

[lionelsoni]

You're quite right that there is little mechanical or esthetic reason for a spiral up that high; but I think that they have another advantage that can be especially useful in shelf layouts:

The sharper the curvature, the farther the tangent must be located from the wall, so that the trains have room to swing out as they enter the curve. So you can get away with a quite narrow shelf if you indulge in large curves at the corners of the room. However, a spiral lets you have your cake and eat it too. You use the long radius to enter the curve, so that, by the time you reach the short-radius middle of the curve, you have moved well clear of the wall. The spiral takes up little more room than the simple short-radius curve, and far less that the simple long-radius curve. I am using a single O27 section (45 degrees) flanked by two O54 sections (22.5 degrees each) in each corner of my wall-hugging loop, so I didn't even have to cut any track for the corners.

I have the 1931 edition of "'Railroad Curves and Earthwork' by C. Frank Allen, S.B., Member American Society of Civil Engineers, Professor of Railroad Engineering in the Massachusetts Institute of Technology". His original 1889 preface brags that "The spiral easement curve is treated originally". So it seems that the spiral goes way back.

[Anonymous]

First of all I am way impressed with the level of knowledge going on here. I had no idea that the subject was nearly so complex. I am bopeful that the Insurance guy can successfully tread on such technical ground.

I hope to do this with some manufacturers standard track sections. I was planning on using MTH as we already have some. Are either of you aware of a configuration for a 90% turn using standard lengths of 042 and 054 track sections? It would seem to me that it probably would not add a lot to the cost of the project to include this subtle detail to the plan.

I am going to a train show where i hope to find a vendor who has what i need and make one bulk purchase of all the pieces that i need to do the job.

[Buckeye Riveter]

Makes good sense to me. However, I guess I wouldn't want my shelf too narrow in case of a derailment and if I did put in the easement curve, I would do it much the same way with the different radius.

The spiral does go back a ways, but as I said the railroads use tables that approximate the spiral equation. In fact, about ten years ago, I had a retaining wall that ran parallel alongside the tracks of Conrail and CSX. Wouldn't you know it that they both do their curve geometry different and could not agree on the clearance to the wall.

Yes, the railroads started using the sprial in about 1880, so I would assume some professor in order to earn his keep presented a paper lauding their use.

When we do curves in the flatlands on interstate type of highways, the degree of curvature is so small that the easements into the curve are not needed, only the super elevations.

[daan]

One thing before you buy. Don't let the starter set tracks guide you with further achievements. It's better to buy everything from a type of track which you really like and reuse it on your basement layout later on, then buying a fit to the few starter set pieces and having to buy all new when you're rebuilding the thing downstairs because it's not really the thing you want.
If you don't want to spend a high amount of money on your trackwork and you want track that is easy to maintain and last a century or two, go for tubular! It's not one of the prettiest rails, but it's by far the most practical in use. It can be bent, rebent, shortened, stays clean almost automaticly (thanks to the railhead shape) and wiring can be easily soldered to it. Besides that it's cheap, relayable and every type of engine (magnetraction, rubber tractiontires or bare steel wheels) has a good pulling power. I use 70 to 80 year old track and it still works great!