Is it to the inside rail, outside rail, or track center? I’d like to use some in a switching area but it’s a tight fit and I need to be precise if everything is going to fit.
John, my last 4X8 layout was built with Atlas 22" radius track at the ends. Made a nice turnback curve with track centers 2" from each edge when done. Has to be a centerline measurement.
the radius is measured to the centerline of the track
have you considered using flex track?
Bending flex track to tight radii can be done but it is hard to get it to stay where you want. It’s simpler to use fixed radius track if you can get it to fit. With 22" radius to the center, I think I can get it to fit the space I have. If the radius was to inside rail, that would make the curve just a bit wide and would have forced me to tweak something to get it to fit.
I can’t see why it can’t be bent to suit…simply use a nail, some string, and a pencil to draw the curve that you want, then put a few finishing nails at various places on the drawn curve, then bend the flex track to-suit, with a few more temporary nails on the inside of the track’s curve. It should stay inplace while you add Atlas track nails to the appropriate ties.
Wayne
I do what Wayne sez. Draw out an arc representing the centerline of the curve, which will be the radius of the curve. Fasten the track length of flex at one end with the center hole of one of the ties pegged/pinned/nailed to the substrate surface, and then proceed to nail the center holes where you find them along the centerline. Works like a charm. If you don’t like nails showing, you can ballast and when it is hard, remove the nails. Or, like many of us do, use a thin sheen of acrylic latex caulking along the centerline and affix the tie bottoms to the caulking. When it dries, remove the nails, and your rails are fixed where you want them.
However, sectional track is a lot quicker, and if laid carefully, can serve you very well.
I’ve also “adjusted” fixed radius track sections, for switching areas, but cutting the plastic strip under the track that connects the ties.
Mike.
John, This is exactly what I do. Any curve 24" or below is done with sectional Atlas track. I have found it too easy to get something out-of-adjustment with flex track and have a short curve that is too tight. Atlas sectional track prevents this.
I have a supply of 24, 22, and 18 inch radius pieces for use in my industrial and switching areas.
I did this same practice on all previous HO scale layouts, and I had no problems with it.
Oh, as for your original question, as was already stated, the curve radius is the center line of the ties.
-Kevin
I also use sectional track for some tight industrial sidings, street trackage, etc.
Sheldon
The Atlas terminology seems to have changed for its track that is shorter than flex track. At one time, its 22" radius curve and its 24" radius curve was referred to as “sectional track”, and its 15" radius curve and its 18" radius curve was referred to as “snap track”. More recently, all four radii curve track have been referred to as “sectional track”.
Atlas sectional track does provide an accurate fixed radius curve in all four instances. That said, and this may raise some eyebrows, if someone needs curved sectional track as tight as 15" radius or 18" radius, N scale ought to be considered instead of HO scale. I say this because most HO scale locomotives and rolling sttock are not designed to operate on curved track less than 22" radius. That’s just my opinion from personal experience.
Rich
Rich,
Do you know what locomotive I would be refering to if I said “B&O Docksider”?
These locos were used to switch industries and docks in southeast Baltimore. Most of the trackage was in the streets.
This was in an era when few freight cars were longer than 50’ and the curves of this trackage were very sharp, even pushing 40’ and 50’ cars right to the edge.
Much of this trackage was built so far back most freight cars were 36’, but this lasted well into the 1980’s before most of it was abandoned.
After the steam locos were gone, small diesels and later Trackmobiles supplied the motive power for this area.
Curves in the range of 175’ radius (24" in HO) were very common in these kinds of locations.
So modeling these kinds of locations with curves as sharp as 18" radius is no different than any of our other selectively comp
It’s been a long time since I had a layout with 18" sectional track on the mainline but my experience is four-axle diesels and steamers as big as a Mikado could negotiate it without jumping the rails. I never had anything bigger than that in those days.
I have another switching area that uses a short section of 18" radius track and my BLI SW7 has no trouble handling that curve. It’s the only loco that goes on that secion. The new switching area I’m building will be switched by a Ten Wheeler and would probably handle 18" radius but I have just enough room to put in 22" track so that’s what I am going to go with.
18" radius is only used on industrial trackage. Hidden mainline curves drop to 22" radius. Visible mainline curves are at least 36". Visible branchline curves can be 24".
-Kevin
Standards on my current layout are very similar to yours. My branchline minimum is 28". I know I could go lower with the equipment I run but I think a little broader curves just look better. Motive power is a Ten Wheeler and a 55’ Doodlebug. 60’ passenger cars and no freight cars over 40’.
My previous layout had a mainline minimum of 28". It handled my UP articulateds and the FEFs but full length passenger cars just didn’t look right going around curves that tight so I upped my standards when I started the current layout.
Looks like I raised somebody’s eyebrows. [(-D]
Sheldon, methinks you play devil’s advocate here since you and I both lust for minimum 40" radius curves on our layouts. Of course, my comments were a broad generalization that if one is building a layout and is forced by space considerations to use 15" and 18" radius curves, he just might be better off modeling in N scale. [|(]
Rich
And, you should be happy with that track configuration, John. It is when we are forced to use tighter minimums than we otherwise would want on curves due to space considerations that problems arise.
Rich
The point is simple, even on my layout with its 36" minimum curves on the mainline, and anywhere large locos or passenger cars travel, there are industrial tracks with sharp curves.
You really want to see sharp curves and crazy trackwork on the prototype - look up the Bronx terminal.
http://www.bronx-terminal.com/
This car float - rail - truck terminal used an oval warehouse, with oval tracks around the outside to unload railcars and trucks loaded inside the oval. The radius of the oval was about 9
If you want tight radius use O gauge [swg]. Atlas 3 rail looks pretty good and most trains will run on O36 track (36 is diameter, radius is half that) and many will run on O27 track.
Paul
I agree with OP, it can be difficult to bend flex track into sharp radius curves…short sections of flex track.
Code 83?
For industrial situations, consider the ATLAS 22 inch radius turnout Item #544 and #545. It has a curved diverging route (like PECO code 100 turnouts) that are designed to fit into a 22 inch radius curve.
I used these on a previous layout. I like the look of the car cut diverging at a consistent curve through the tracks, rather than the curve…straight…then sharp curve motion you get with a standard #4 turnout that has a straight diverging path.
It also help with tight spaces since the track is already more sharply angled right after the frog.
Works well and looks better, what’s not to like.