Recommended curve radius


B

bennyboots

Noob model railroader
What would your minimum curve radius be on a layout where you do not want restrictions on what kind/size of rolling stock and locomotives you run?

I am trying to decide how big to build the tables for my new layout. I will have roughly the equal of two 4x8 areas in the shape of an L. In addition, there will be a staging yard going through the wall into a bedroom closet.

I have no idea what kind of locomotives or rolling stock I will run in the end but I do not want to limit myself due to tight curves. It will be all modern diesels. I would like to run intermodal double stacks, Im not sure what restrictions besides hieght there are for these cars.

Any advice from you guys would be very much appreciated! Thanks.
 
I would say at least 30" minimum radius, and you'll be fine with most any equipment out there.
 
Scale might matter

Scale might matter here. Assuming HO as did Motley(Michael) then 30" while good is not even under discussion on a 4' * 8' table. 4' just doesn't cut it for the requirements listed - one reason why I don't have a layout yet :(

take care ,,, ken
 
With 4x8, 22" is largest radius you can run. My 6 axle diesels and passenger cars work ok on these and 4-8-4 steamers work. I think you might have problems with 2-10-2 if they don't specifically say what radius is supported. There is also a difference between working and looking good while working. I have to accept working due to similar limitations.
 
bennyboots said:
What would your minimum curve radius be on a layout where you do not want restrictions on what kind/size of rolling stock and locomotives you run?

I am trying to decide how big to build the tables for my new layout. I will have roughly the equal of two 4x8 areas in the shape of an L. In addition, there will be a staging yard going through the wall into a bedroom closet.

I have no idea what kind of locomotives or rolling stock I will run in the end but I do not want to limit myself due to tight curves. It will be all modern diesels. I would like to run intermodal double stacks, Im not sure what restrictions besides hieght there are for these cars.

Any advice from you guys would be very much appreciated! Thanks.
Click to expand...
What scale are you modeling with? Z or G? With Z, 8" would be more than enough for anything out there, while G would probably have trouble with 40".
 
bennyboots said:
What would your minimum curve radius be on a layout where you do not want restrictions on what kind/size of rolling stock and locomotives you run?

I am trying to decide how big to build the tables for my new layout. I will have roughly the equal of two 4x8 areas in the shape of an L. In addition, there will be a staging yard going through the wall into a bedroom closet.

I have no idea what kind of locomotives or rolling stock I will run in the end but I do not want to limit myself due to tight curves. It will be all modern diesels. I would like to run intermodal double stacks, Im not sure what restrictions besides hieght there are for these cars.

Any advice from you guys would be very much appreciated! Thanks.
Click to expand...

A quick rule of the thumb is that a minimum radius curve should be 2.5 - 3 times the length of the longest piece of rolling stock, whereas a good looking curve needs to be about 4 times the length of the longest rolling stock, and a curve where you want cars to couple automatically when you push them together should be at least 5 times the length of the longest rolling stock.

An 89 foot car is 89 x 12 = 1068" in real life.
In H0 scale, it is 1068" / 87.1 = 12.3" long --> Minimum curves around 30-36"
In N scale, it is 1068" / 160 = 6.6" long --> Minimum radius around 18-20"

A 22" radius curve (which is the most you can get on a 4-foot depth if you want a return curve, can handle car up to 22" / 3 = 7.3"

If it is H0 scale, it corresponds to 7.3" x 87.1 = 638" (53 feet)
If it is N scale, it corresponds to 7.3" x 160 = 1168" (97 feet).

So if you are in N scale, you are okay. If you are in H0 scale, and want 180 degree turnback curves within 4 feet of depth, you should stay with 50' and smaller cars and smaller to medium sized locomotives.

If you want it to look good on an outside curve, you can handle 22" / 4 = 5.5" long cars (40' cars in H0 scale, 70' cars in N scale).

I would very much recommend N scale if you want to run long stuff on a 4 foot deep table.

Smile,
Stein
 
I agree with all of the above, N scale may be the way to go if you want those big turns.

The most demanding diesel engine I can think of in terms of required radius would be the DD40s.
 
Sorry, I should have mentioned I would like to model HO scale. I see that 4 x 8 's are not going to cut it. I might just have to go 5.5 feet on each end of the L. It is possible but ill have to see what the GF thinks of this constantly expanding idea. Thanks for all your advice!
 
bennyboots said:
Sorry, I should have mentioned I would like to model HO scale. I see that 4 x 8 's are not going to cut it. I might just have to go 5.5 feet on each end of the L. It is possible but ill have to see what the GF thinks of this constantly expanding idea. Thanks for all your advice!
Click to expand...

A smarter idea might to turn the layout inside out, so the operator is inside and the layout is on the outside. This has several consequences:

1) your curves do not need to have the center of the circle on the table, so they can be closer to the edges

2) You only need one wider aisle in the center, not one narrow aisle on each side

3) Visually, you get less clutter when the scenes are not behind each other, but beside each other. You can see across a table, but you do not see what is behind you.

4) You can have stuff above and below a layout along the walls - no so easy when you have narrow aisles around a big table.

Illustration - showing two ways of having 30" radius curves in a room

table-vs-shelves.jpg


In the first case (left), the room needs to be 10.5 foot deep to have room for a 180 degree curve on the table, with 30" aisles on both sides. .

In the second case (right), you have a 4 foot wide aisle in the center and 30" radius curves, but you can do it in 8 feet of depth - which is the same as you would have needed for a 4 foot wide table and two narrow aisles.

Grin,
Stein
 
Last edited by a moderator:
That is a really great idea I never thought of that. I wish I could come out 10.5' but it just isn't possible with this room as it is an open space heading into the entertainment room. I am limited to staying along the walls.

Hopefully this very low quality and not to scale version I just made on paint works so you can get an idea of the area I have to work with.

If I did build the tables to around 5'6" to accomodate the curves I would have the track curve around a little more than 180* to slim up the mid section of the layout and hopefully not clutter it too badly. I don't plan on going crazy with industries and cityscape. I was thinking of mountains on the left curve and praries on the right curve. Maybe a little town and some light oil industry in the middle. (I'm from Saskatchewan, Canada and now live in Alberta.) I want to run a double mainline in this arrangement with crossovers so I could have two trains running and alternating on the inner and outer tracks. As far as spurs and sidings I have no idea. I do want to have a diesel house somewhere near the middle of the layout. I had thought of alternating the hieght of the two tracks at different points along the route to give it some topography. I thought no more than 2" difference at any time tho.

I also thought of putting the thing on wheels to pull it out from the wall. But that will eliminate having permanent tracks running through the wall into the closet which I was kind of keen on.

Do you forsee any other problems with this style of layout? Any other words of wisdom? The last layout I had was a figure 8 and I was young so this is really going to be my first kick at the can. I know its not ideal but I really want to be able to just have the trains run and watch them go on a continuos track.

Your help is greatly appreciated.
 
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