Back in after 20 years. Great changes, including this site.
4X8 surface. So far, one mountain with two tunnels. Using the Atlas paper track planner, I find that getting the track through the tunnels and back around to the main line requires 9 1/2 radius curves. Is there any way to do this using wider curves or should I just give up hope of running passenger trains?
Thanks. Sid
Howdy, Sid. [#welcome] Welcome to the forums.
I gather that your 4 x 8 is N scale. That’s equivalent to 7 x 14 in HO, which would give plenty of room for Pullman-rated curves if the track plan is kept simple. However, if you try to make things too complex it’s entirely possible to end up with a track plan that would be limited to teakettle 0-6-0Ts, diesel `critters,’ ore jimmies and four wheel bobber cabeese.
I don’t want to sound elitist, but using any manufacturer’s fixed-curve sectional track is NOT the optimum way to achieve a perfect model railroad, or even a particularly good one.
Lacking any real data on your track plan, that’s as far as I care to go. My own scale (1:80,) prototype (Japanese,) givens (a double garage) and druthers (Including a mountain goat path with curve radii equivalent to 7 inches in N scale) are very different from yours.
Chuck (Modeling Central Japan in September, 1964)
Hi Sid
The LDSIG (Layout Design Special Interest Group) developed a rule of thumb relating radius to length of longest cars. The rule is fairly conservative. But it does allow pretty quick evaluation of the practicality of a given curve radius in light of planned operations (the intent of the rule of thumb). All the empirical and anecdotal evidence I have seen suggests that the 3X minimum is right on for long trains and operations with a helix.
Here are some curve radius guidelines based on the lengths of your longest pieces of rolling stock.
2X - Some model equipment may be able to track reliably on 2X their length, but this is generally considered pushing it.
3X - Making your curve radius at least 3X the length of your longest cars gets reliable tracking around curves, but looks toylike.
4X - If you make your curve radius at least 4X, your longest cars will look much better on curves.
5X - If you make your curve radius at least 5X, your longest cars will couple easily with minimal manual fiddling of the couplers.
This measurement is based on the length of your longest car (coupler to coupler).
[quote user=“Paulus Jas”]
Hi Sid
The LDSIG (Layout Design Special Interest Group) developed a rule of thumb relating radius to length of longest cars. The rule is fairly conservative. But it does allow pretty quick evaluation of the practicality of a given curve radius in light of planned operations (the intent of the rule of thumb). All the empirical and anecdotal evidence I have seen suggests that the 3X minimum is right on for long trains and operations with a helix.
Here are some curve radius guidelines based on the lengths of your longest pieces of rolling stock.
2X - Some model equipment may be able to track reliably on 2X their length, but this is generally considered pushing it.
3X - Making your curve radius at least 3X the length of your longest cars gets reliable tracking around curves, but looks toylike.
4X - If you make your curve radius at least 4X, your longest cars will look much better on curves.
5X - If you make your curve radius at least 5X, your longest cars will couple easily with minimal manual fiddling of the couplers.
This measurement is based on the length of your longest car (coupler to coupler).
Who am I to disagree with Paul, but …
obviously, he is right. but who has the space to have 34" radius curves in N scale? That´s what you need if you plan on running those modern 89´cars and go for the factor 5. Most HO scale modelers don´t have that.
Even with a factor of 4, you are still at a radius of 26 1/2" - quite a lot.
In one of the recent MR´s, Neil Besougloff wrote in his monthly comment about using an HO scale plan for N scale, an approach which I think is feasible.
Are you in N or HO? I am also assuming N, and that you mean 9.75" radius curves…
Code 55 Atlas track in N scale has curves up to 30.609" R. But you can find more comfortable 18.75"R and 20"R curves here:
http://www.modeltrainstuff.com/Atlas-N-2024-Code-55-Track-1875-Radius-Curve-6-p/atl-2024.htm
http://www.modeltrainstuff.com/Atlas-N-2026-Code-55-Track-20-Radius-Curve-6-p/atl-2026.htm
you can also find 21.25"R curves {43" of 48" allows for 2.5 incehes on either side of the 4x8 for a “safety zone”} Here:
http://www.modeltrainstuff.com/Atlas-N-2028-Code-55-Track-2125-Radius-Curve-6-p/atl-2028.htm
You can use the 21.25 outside the 20 if you want double mainlines, or the 20 outside the 18.75 for same only smaller.
You WILL have to build a tunnel to accomodate then if you want that too.
I would say you could run larger equipment on those fairly well.
Just food for thought…
[8-|]
Rich, Paul is indeed helpful in posting the curve radius rules-of-thumb, but from the “credit where it is due” department they originated with the Layout Design SIG and are found here: LDSIG Curve radius rules-of-thumb
Ulrich, note that the 5X suggestion is only for best appearance and automatic coupling on curves. It’s not suggested in any way as a “requirement”. That figure would be more in the 2X to 3X range., per the rules-of-thumb linked above.
The Original Poster’s question is confusing to me. I don’t know why he is limiting himself to 9 3/4" curves if he has more space.
Byron
[quote user=“cuyama”]
Rich, Paul is indeed helpful in posting the curve radius rules-of-thumb, but from the “credit where it is due” department they originated with the Layout Design SIG and are found here: LDSIG Curve radius rules-of-thumb
[quote]
Byron, thanks for that information and source.
And, I figured that Paul was so smart to come up with that all by himself. [;)]
Rich
It depends, it sounds like you’re using some type of published trackplan that requires reverse loops?? It may be that to do it exactly as published you’d have to use curves that sharp. You can always do another track plan with broader curves.
The largest curve you can fit on a 48" wide layout is 22" radius. Many HO 4x8 track plans use 18" radius curves which are considered sharp to very-sharp in HO, but 15-18"radius curves are broad curves in N which any equipment can use. So maybe you could look into a book like “101 Trackplans” and check out the HO 4x8 layouts, and build one of them, only using N scale track.
p.s. If you haven’t already done so go to www.katousa.com and check out their line of N scale track.
As you are using Atlas paper track planning tools, you might as well download Atlas RTS and let it help you with track layout and usage of flex track instead of sectional.
Gidday, To be fair Paulus Jas did credit the "Layout Design Special Interest Group".
I, very recently, found a reference to the “LDSIG rule of thumb” in an older thread so was aware of their excellent work which, in my opinion, is worthy of being bought to our attention from time to time.
Just my two bobs worth.[2c] [:)]
Cheers, the Bear.
Hi gentlemen,
I did mention the LDSIG as source for the information. However I copied / pasted an entry from some time ago. If I remember well it was written by Fred Wright.
He added a remark about curves and grades (in a helix) I found very important. Without being specific the combination of the two can lead to derailments which do not occur on flat layouts.
Byron Henderson (Cuyama on here) has more then once warned about problems with a to tight radius in a helix. A tight radius results in a steeper grade; together they can cause string-lining. A car climbing the inner track till it drops over.
For newbies it may sound rather complicated, not every train will stay in the tracks regardless the length and weight of the cars or coaches, regardless of the radius and grade of the tracks. Here the ratio’s by the LDSIG come very handy. IMHO keeping them between 2,5 and 3 for the mainline will probably work well.
The remark about the 1:5 ratio might lead to paying attention to how you envision (un)coupling.
Shoving a train is even more prone to derailments then pulling. Knowing all this might and should lead to taking some difficult decisions. Are the cars, coaches and engines you would love to operate in line with the required minimum radius and grades? Maybe even a change of scale is needed.
The original poster should step in again, maybe he could be more specific about the problem he faces.
Smile
Paul
Thanks Chuck. Appreciate the advice.
Sid