Track Layout Advice

[pathboy]

After years and years of wishing and thinking, I'm finally getting serious about putting down track in my backyard and adjacent recently purchased land. Aside from years of subscriptions to GSQ and 7+, I've little experience due to the lack of spare time over the last few decades.

Eventually the track of my dreams will cover the 4 acres of adjacent wooded land, but I'm starting out with a small loop in my backyard with at least 3 switches built in (one for train storage, and two for future expansion).

My questions:
How does the radius of a curve affect the usability of the track?
What generally is the tightest curve desirable?
What's the deal with the different numbers associated with frogs?
Steel or aluminum track?

I'm at a point when cost isn't as big of factor anymore. I'd rather save time of future repairs, etc. I'm planning on using plastic ties but still not totally sure about the type of rail. Aluminum may be easier for a novice to deal. Some of RMI products seem appealing as well and I wonder if anyone has any user reviews (ie true-tie track system, pre-build switches, etc).

Thanks!

[locodan5416]

Ok, first question, what locomotive are you going to use?

Also, where are you located? And by that I mean what is the weather like in your area?

[pathboy]

I'm in northeast Texas -- so a lot of hot and a bit of cold. The ground is fairly stable in my area with quite a bit of clay.

As for the locomotive, the first will be an electric (Cannonball is a local producer-- I was looking at a Super Mac with some assorted passenger cars). That's a good question, because as I would eventually like to delve into a live steam engine, I'm thinking electric will provide less frustrating variables. However, I want this first section of track to be able to be widely used by different types of locomotives (since I'm not sure what type of train I might decide in 5 to 10 years from now). The first part of the track will be a rough loop that I hope to extend onto the larger part of the property in years to come.

[locodan5416]

Well, there are some options, I don't know where the closest live steam club to your house is, but I recommend you taking a visit and ask them about their track. I live in the northern edge of Ohio, and where we have a had a moderate winter so far (**knock on wood of course**), it tend's to get cold, I think last winter we had around 100" of snowfall, and during the summer it will consitently be around 85-90 degrees. What I know about track construction and expansion issues are different then what you'll expierence.

When you set up the design, try to design it for the largest engine you could invision building, I know this is bad for those texas people that want the biggest and best, no offense taken I hope...but realistically think of the largest locomotive you would make/purchase. Also, make your radius as large as possible, this will be a big factor.

On the issue of the curve radius itself, I am convinced no one knows what they are doing when they line up a curve. I've seen templates to pre-made track panels and 60' tape measures all in between. Personally I say avoid curves altogether, even though that isn't possible. You do want the radius large, and the way I recommend doing it is as follows...

First, figure out where the curves for the loops will be, buy a large tape that will go 50-60 feet out, and bring along a friend that won't mind an afternoon out in the Texas sun. Have a large stake and drive it in the ground, and extend your tape out 50 feet at least. Now, with your friend holding the stake and tip of the rule, draw not just a quarter circle, but overshoot the arc so the curve will extend. And when you do this have both a bottle of spray paint and stakes to put into the ground. Your making the centerline of the track. You want to go around every 9 feet or so, I know at my club at least the track is made at 10 foot panels.

After you have the four curves all set, same process, you have to make the track.

In the issue of steel vs. aluminum, try to get the cheapest price. There's no sense paying a little extra for aluminum or for steel, depending on the area. For what little harm the steel will do to your wheels, naw, you'll save more with the cheaper rail, and aluminum looks kind of hookey if you ask me.

I recommend you start small, and work your way around, and get it right. Your better off spending the time involved in the track maintence, (Yes, I said track maintence, which is required) then derailing because the track is slighty off-level.

I wish you luck, some of the better runs I've expierenced have come on people's personal tracks instead of the club track.

[GoldenSpike53]

That's some good advice from Dan. I would like to add one item into the discussion about aluminum vs. steel rail.

Aluminum is lighter weight than steel, which makes it somewhat easier to install, but it also has a much higher scrap value than steel. Aluminum scrap is bought by the pound, steel by the ton! In consequence of this one consideration, aluminum rail is attractive to robbing scavangers who don't care who they steal from. Our club track in Sacramento has been vandalized three times in the past year, on one occasion putting the track out of commission for over four months. And we recently had word of a club member whose aluminum rail was ripped up and carried off by a thief or thieves.

Another virtue of steel rail is that it can be easily welded together at the joints so you wind up with "ribbon rail" instead of having joint splices every ten or so feet. Of course, you can still use joint splices for steel rail, but the option is there to do this. I've worked on our club track as we've replaced areas of aluminum rail that were stolen, with steel rail. I think it makes quite a difference.

Lastly, regarding curves and curve radius...there are more than one way to skin a cat or line up a curve. You may not be able to set a stake down at the center point of a curve to run a radius with tape. At our track we have a little contraption that is basically a piece of wood about ten feet long with an attachment at either end to hold that end against the rail. In the center is a straight edge with graduations on it projecting out perpendicular to the wood section. When this is laid against the inside rail on a curve, the straight edge measures the amount of curvature between the two points touched by the wood section. With a little math, you can calculate the radius of the curve. And by checking various points along the curve, you can make sure the rate of curvature is consistent. This is something hard to do with a tape or measured cord trying to paint a curved line if you are working around uneven terrain or trees or other obstacles. I suspect the nearest club track would have something similar to this and could explain how to use it and the formulas or mathematics involved. (I've never been great at math, but I'm sure the formula isn't too complicated.) This method uses chord measurement (the distance between two points on a circle that do not intersect the center).

So there's another method in case you need it.

Dale Dennis

[locodan5416]

Yeah, but if your building a home track, whats to say you can go out and weld some pieces of track together? I wasn't aware people would be so desperate to attempt the aluminum rail, maybe that reflects our economy? It was shown in the movie October Sky where they attempted to steal a steel rail and were spocked when they heard a train whistle.

I just assumed with the clay-ish soil, that the way I described wouldbe better, where your jig would as well work.

The method you described involves the calculation of dS (excuse me as this really isn't calculus, however there is no delta symbol)...and while I'm not a math major but a mechanical engineering major, I thought that calculation was 1. too gruesome for a hobbyist, and 2. too tedious off a cut on the wood for a begineer. Please excuse me pathboy as I truly mean no offense, however my mindset was you wanted the simplist way possible. Also, you'll not your method works only when you are physically laying the track, whereas what I described lets the builder see the railroad take shape, and depending how much it rains, see his--or her--railroad being built... however i do not know of one model railroad built under the crack of the wifes whip

[pkastagehand]

goldenspike53 said:

At our track we have a little contraption that is basically a piece of wood about ten feet long with an attachment at either end to hold that end against the rail. In the center is a straight edge with graduations on it projecting out perpendicular to the wood section. When this is laid against the inside rail on a curve, the straight edge measures the amount of curvature between the two points touched by the wood section. With a little math, you can calculate the radius of the curve.

Dale Dennis

r=(chord length squared plus 4 times height squared) divided by (8 times the height) or

r=c^2 + 4h^2/8h

where:

r=radius
c=chord length (your board going from rail to rail in a straight line
h=height of the arc measured from chord center to arc center (your straight edge perpendicular to board)
^= raised to the power of
/=divide (of course)

Just looked it up in Machinery's Handbook, had nothing else going on just this minute.

And one could weld aluminum rail if you have the welder (or can hire one). With the expansion/contraction rate of alum. I'm not sure this would be a good idea. You might want the joints to allow exp/cont.

[GoldenSpike53]

Thanks for the formula, pkstagehand. That is a valuable thing to know, and the math isn't too complicated. It's actually pretty straightforward. One question: I assume you would be using common units within the formula, so you would want to convert to some common unit first, then reverse that when finished with the measurement? So rather than using feet as the length of the chord, you would likely use inches, since the height of the arc would probably be in inches?....

Dale

[pkastagehand]

goldenspike53 said:

One question: I assume you would be using common units within the formula, so you would want to convert to some common unit first, then reverse that when finished with the measurement?
Dale

"You are correct sir!" That is typical of Mach. Handbook and math in general...plus I checked it to be sure.

With ten foot chord length and a height of 2.504 inches you get a 60 foot radius (+/- a fraction of an inch, depending on how many decimals you carry things out).

Paul

[locodan5416]

yeah, as they always say, standard units in, standard units out...inches would be the best way to go, except for those across the pond, who would probalby fancy millimeters for this job, since we all know engineering is done with every-third decimal place, as i have yet to see a centi-meter in school---except for those centimeters running across the floor of my house that my girlfriend does not seem to appreciate too well.

[n8186w]

Other quick notes:
1. The curve radius, middle ordinate, and bearing-from-tangent are all measured to the guage side of the outer rail.

2. In prototype practice (running a consolidation on the Virginia and Truckee Railroad in Nevada), we had guage tables that we used to increase the track gauge for all curves tighter than 10 deg. Remember, that the flanges are safety devices. Ideally, the flanges should never touch the rail. For long-wheelbase (i.e., steam) locomotives, the track gauge needs to be widened on curves, othewise the wheels will tend to climb the rail. I no longer have the recommended guage tables, but just doing some calculations against a 30" wheelbase scale locomotive, it looks like 1/8" of gauge relief for a 60' radius curve and a 3/8" gauge relief maximum for tighter curves (3/8" at 30 ft. radius and tighter), would be about right.

After all that, we still had an arch bar truck on one passenger car that used to like to climb the rail on one place on one curve. We lubricated the king pin bearing surface, still no luck. So, we turned the car end-for-end and the problem went away. Go figure.

[paulwestover]

Bittercreek western as well as Train mtn. are both going to steel as the alluminum wears out. I belong to Riverside which has alu. rail and lately they have been losing alot of rail to thieves so if you have the money spend it on the steel rail, just my thoughts.

[ngtmodels]

Hi,

I'd like to add a question to this one, if I may, please.

I'm looking for a quality Number 8 and 10 FROG use with standard 1" rail..., not the GIANT West Coast Rail.

Any ideas as where to shop?

Thanks,

Zoë