Minimum Radius for Passenger Line

[HAZMAT9]

I've been scratching my head this past weekend to see how I would incorporate a passenger line into my Granite Gorge and Northern Railroad. So far the track plan calls for a minimum radius is 18" with a few 22" radius pieces at each corner. I would like to run full length 85' Amtrak cars on my layout, though I'm afraid of either derailments or unrealistic looks. More concerned with the unrealistic looks since I tested the 85 footers on a loop track with 18" min radius and it seemed to work fine. Does anyone have any suggestions? I had planned on adding another mainline though I'm having problems figuring out how much room I need to add on my table width wise. For example, if I go with 30" rad do I need to add an additional 2, 3, 4....feet to the width? Any help would be greatly appreciated, or maybe I can get away with what I've got... can't sleep too well trying to figure this out. Many Thanks, Steve

[Anonymous]

Steve
If I understand your question correctly, a 30" radius return loop would be 5 foot wide at the track center line. At a minimum width of 5 1/2 feet your track would be a few inches from the edge of the table. Add easments and you are looking at 6 foot wide table to be safe.

[DigitalGriffin]

Most cars will handle on a 24"

If you wanted a more gradual turn, you could start with 30" and work your way down to 24" for an easement effect. That would keep things from getting too wide if 5 1/2' is too wide.

[IRONROOSTER]

The NMRA has a page of recommended curves http://www.nmra.org/standards/rp-11.html for 85' cars you they recommend 32" without diaphrams and 40" with. As we all know most passenger cars will operate on 24" or 18", but operation and appearance is better if you can use the broader curves.
Enjoy
Paul

[HAZMAT9]

The layout so far is 5x9 w/o adding the extras that I originally proposed. The current mainline loop comes just about to the edge of the table on the width (5 feet). I can easily go 6 or 7 feet on the width but would be pushin' it. I'll go w/ the 30 radius....thank heaven for flex track. I'll have to re-figure the scenery out since I need to re-position a few towns and stops. Problem is trying to interface a bit of urban w/ mucho rural....it's a challenge. If I decide to add in a small city scene off to one side, does anyone know how tight of a radius I can get away w/ for a streetcar or trolley? Thanks for the great help so far!!

[HAZMAT9]

Paul,

I checked out that site earlier today and was a bit confused, but it now makes sense..I should be looking at Category "O" ....I was looking at "P" oops. Now it does make some sense. Hey Gary how did you figure out the width I needed in terms of easement.....what do I need if I decide to go to 40" radius? Steve

[SpaceMouse]

The larger the radius, the lees the easements come into play.

But you are developing another problem. If you go with a 40" radius and expand your layout to 7 x 9 you are getting a layout too wide to be able to reach in the center. You would need to build an access area 20" at least to beable to get to your track and scenery.

[chateauricher]

Ahem ! What scale are we talking about here ??? Once again, you all seem to forget to mention that critical fact.

18 and 22" radius curves will work and look great in N-scale. But won't be adequate in O-scale.

[Anonymous]

QUOTE: Originally posted by HAZMAT9

.... does anyone know how tight of a radius I can get away w/ for a streetcar or trolley?

Steve
Depending on the wheel base, 12 inchs radius is safe but I've seen 5" radius on some Micro Layouts

If you're intrested in trolleys and tramways, check out these sites.
http://www.modeltrams.co.uk/index.htm look at their track
http://www.btinternet.com/~beckits/ neat stuff
http://www.labellemodels.com/dhot.htm#top craftsman kits
http://www.bowser-trains.com/hotrolleys.php good 'ol Bowser

[HAZMAT9]

Sorry folks, this is an HO layout. I plan on adding some access hatches to the layout to get into the middle for detail work. Sounds like I may have enough room for a streetcar route through one of the towns. I plan on major revisions to the scenery w/o affecting the trackplan since we're ready to lay track w/ the exception of tying in the 40" rad line. Will go w/ the the 40" mainline, boy talk about some major revisions! The wife is going to freak as this layout continues to grow like the mold! Thanks for the much needed help. Steve

[Adelie]

I drew out a 40" eased curve in CadRail and it used a total easement length of about 26.5 inches (13.25 on each side of the tangent) , with an offset of just under 3/4".

In terms of whether you should ease them, I have 27" mainline radius minimums in N-scale, and I ease them. Looks better and provides some benefits. Of course, you may wind up needing a separate structure for your "5x9" layout. If so, an extra room for you to sleep in might be adviseable! [(-D][(-D]

[SpaceMouse]

QUOTE: Originally posted by Adelie

I drew out a 40" eased curve in CadRail and it used a total easement length of about 26.5 inches (13.25 on each side of the tangent) , with an offset of just under 3/4".

In terms of whether you should ease them, I have 27" mainline radius minimums in N-scale, and I ease them. Looks better and provides some benefits. Of course, you may wind up needing a separate structure for your "5x9" layout. If so, an extra room for you to sleep in might be adviseable! [(-D][(-D]

So using easements with the CADRail calculation figuring a straight of one diesel train length or about 12", the dimensions of his layout giving 2" space on each side of the oval would be: 85 1/2" X 142"

[jkeaton]

You wrote that
"More concerned with the unrealistic looks since I tested the 85 footers on a loop track with 18" min radius and it seemed to work fine."

It's not running the 85 foot cars around a simple loop of 18" radius that will be the problem - it's when those 18" curves meet switches, straightaways, or make reverse curves that you may find troubles. The other guys have covered off transition curves, but I would just caution that a switch near a curve can also cause a problem.

Jim

[HAZMAT9]

Not to seem stupid, but can you explain the term "easements?" I just figured on adding about 2 ft. to the width of the layout for a total of 7 feet, so I would have a 7x9 or so, instead of 5x9. I figured this would help to give me more trackside scenery room as well with the added 2 feet. I just about went through the roof w/ the RTS program which is a pain trying to figure things out....going back to the Atlas HO-28 plan in the book and sketching in the added passenger line. Steve

[SpaceMouse]

That was why I was suggesting that maybe you didn't need easements.

Explanation of easement.

Suppose you have an 18" radius turn. That is a pretty tight turn. Whenr you loco comes of a straight and goes into this tight turn, it veers sharply. If you were to gradually ease into that curve starting out with a slight turn, and gradually increasing the tightness of the turn until you reached the 18" radius, that would be an easement.

[HAZMAT9]

Gotcha now it's making sense. Thanks! Steve

[Adelie]

Performance-wise, you get more bang for the buck by easing curves than by going to a slightly larger curve. For instance, if you are comparing, say eased 18" and non-eased 21" curves, the rolling stock will usually behave better on eased 18" curves since it gets transitioned into the curve rather than lurching into it.

Truth is, somewhere between 40" and eased 24 - 30" curves is probably where you will end up. In the end, something winds up being compromised to fit into the available space. If it were me and I had a 7 x 9 space in HO, I'd probably settle on eased 30" curves, and use the extra space for sidings, scenery, etc. In 5 x 9, I'd be trying to use eased 24" curves. But that's just me.

[HAZMAT9]

I guess I'm fortunate to be using flex track instead of sectional. Just for FYI, if someone was to use sectional, and let's say you have either a width of 5 or 7 feet, what track would be used to figure out let's say a 30" curve? The only thing that confuses me is actually measuring the curve. I mean you have out there 15", 18" and 22" radius sectional track available, how do you come up with a 30" curve.....is there a calculation or something....just call me a slow learner. I can just remember way back as a kid building a cramped layout using 15" radius track and trying to run a DD40 on it.....oooops! Steve

[Adelie]

I guess the short answer is - you don't!

Somebody (maybe Shinohara) used to make fixed radius curve track, but I don't know that it is still around. Tru-Scale used to make wood roadbed in various curve radii which pretty much took any work out of flexing track to the correct radius, but that stuff is probably rare these days, too.

I don't know what Bachmann or one of the track/roadbed combos (easy track, unitrack, etc) makes out of the standard 18 or 22" realm.

In N-scale, Atlas makes some strange curve sectional track, at least in code 55.

That's the nice thing about flex track and flexible roadbed. I needed an 18.5" radius on one of my helixes, and as long as I had a yardstick and a drill, I could have it!

[HAZMAT9]

Just was kinda interested how they did it in the "old" days before flex track.

[Adelie]

Flex track has been around for a while. I remember HO sections with brass rails and fiber ties. Track was stiff as a board. Not hard to bend, but once you did, it was not going to spring back on its own.

Before that people probably hand-laid their track if they wanted to get so radical as not following the radius manufactured. That is slightly before my time (but probably not much!).

[Anonymous]

QUOTE: Originally posted by HAZMAT9

.. Hey Gary how did you figure out the width I needed in terms of easement.....what do I need if I decide to go to 40" radius? Steve

Not exactly. There is a bit of geometry involved depending the equipment length. A easment isn't really needed for curves over 30" radius.
However any curve will look better by adding easments. Is your reverse curve more than 180 degrees? If so, easments will not add much, if any, width of the layout.
Adelie figured an offset of 3/4" for a 40"radius. So then, an 80" diameter curve, plus easments and some space from the edge for saftey, I'd say 7 1/2 feet of space would be a safe minimum.
Not what you like to hear, is it? But then you don't really need easments with such a wide curve. That you would be at your 7 foot limit. However, you should add a guard rail at the edge.

[Anonymous]

QUOTE: Originally posted by HAZMAT9

...can you explain the term "easements?" Steve

Here's another explanation for Easments

[Anonymous]

QUOTE: Originally posted by HAZMAT9

...If someone was to use sectional, and let's say you have either a width of 5 or 7 feet, what track would be used to figure out let's say a 30" curve?..

In the Atlas track plan books, they show how to add easments to an 18" radius curve. A 1/2-18"r section is placed in the middle of the reverse curve. At the ends of the curve, a 22"r section is placed at each end instead of a 18"r section. It adds 1/4" to the radius (1/2" to diameter) center line.
I don't know of any sectional tracks larger than 22"r.

QUOTE: The only thing that confuses me is actually measuring the curve. .....is there a calculation or something....Steve

Welcome to the "I'm not a rocket scientist" club, which I'm a member of. You can print out easment templates or use the stick method (read further down). You can buy a Yardstick Compass to draw curve center lines. I made my own out of 3/4" X 3/4" stick with a hole on one end, tight enough to hold a nail and more holes, to hold pencils, for the track center line and the road bed edges.
You can draw directly onto a sheet of plywood if you are using the cookie cutter method. But that won't work for spline roadbed or if you use Rick Rideouts method of sub-road bed (I can explaine that later if you like).
I made templates out of 24" X 28" poster boards. I taped the poster board a work table and drew out the center line and the road bed edges. For marling track centers, I cut out along the center line and inner road bed line. For templates that are as wide the road bed, I cut at the road bed lines. I used the first template to draw out the others.
As Adelie said, the offset is 3/4" for an easment on a 40"r curve. Draw the full curve center line with the compuss or templates and continue drawing a straight line for a few inches at the ends of the 180 degree turn.
Mark 3/4" from the the straight center line (the line comming off the curve) and that is the center line for the tangent (straight) track.
Use the easment templates to connect the tangent line with the curve. Or cut a piece of wood 1/8" thick X 3/4" wide X whatever length needed to round more than half the curve. Have someone hold one end of the stick on it's narrow edge down at the middle of the curve along the center line. Bend the stick to the tangent track and draw the center line. That will give you an easment.
Any questions?

As for myself, I use spline sub-road bed for my curves and the easment comes naturally as I build the sub-roadbed. It's like the drawing with the stick method.

[Anonymous]

QUOTE: Originally posted by HAZMAT9

...The wife is going to freak as this layout continues to grow like the mold! Steve

Beware of the mold! [;)]
Ask the wife hold the easment stick while you draw out the center line. If she is paying attention, and I'm sure she will, she'll figure what you're up to and It won't be so much of a shock and it'll bring up the issue before you lay track. Just something else to think about.
[yeah]
[%-)]

[HAZMAT9]

Finished addding another two feet to the width for a total of 7' and added an additional 3' to the length for a total of 7' by 12'....this thing is swallowing up my tiny garage. I do agree that some of the calculations are pretty serious, reminds me of my horror days in college math class. Wi***heir was a program out there that you enter your flex track the way you want to design it and it spits out what the minimum width and length of your bench work in order to gear how big your layout is going to be......if the software is out there, I couldn't figure it out. I had a heck of a time trying to figure out RTS and El Dorado! BTW, I just about had to pick up the wife's eyes off the ground once she saw walked in the garage and just about tripped over the expansion area. [:0] Steve