Putting a couple of Peco #4 Wyes into our main loop to create two connecting tracks to our upper loop and a bonus third loop including a reversing section instead of including the reversing section in our upper loop as we had before. This is for the layout I share with two others.
We have another Atlas Wye, which I think is a #3, inside our one reversing loop.
This got me to thinking that Wye turnouts usually create an S bend of some sort.
Then of course so does a crossover , although a set of double curved turnouts do not. I’ve included a three turnout, three track crossover using three Peco #7 double curved turnouts for space reasons on my own layout.
We had two #8 crossovers forming an X section (or two reversing loops if you prefer) which created S bends. Our longest trains would happily transit either #8 crossover at maximum speed with no derailments.
So, why the exhortation against including an S bend in your layout?
Any straight turnout crossover will create two alternative S bend routes anyway. If you have one why not several?
#3 Wye is equivalent to #6 turnout in each direction. Peco #4 Wye is equivalent to #8 and either angle of frog will create a crossover that includes an S bend for each crossing route. So a Wye is no more troublesome than a crossover, in theory.
A reverse curve causes more car and coupler offset than a curve and a straight. Increased offset contributes to the possibility of a derailment.
Why a crossover is less of a problem than a typical reverse curve:
Track switches typically have a larger nominal curve radius than the other curves in a layout. #6 is said to have a 48" curve. Compare that with the curves on the rest of a layout.
The overall length of the reverse curve is short for track switches. And there is a straight section in between the two curves under discussion.
One, not two. Right?
I plan on doing that on a double track main with industrial leads on either side. I’ll be using #10 and #8 switches. I do not think I will experience any problems. Minimum mainline radius is 48". This minimum will hold for trackage that is used by 85’-90’ cars, and mainline locomotives.
I have S curves on my layout. Most of my trains are 10-20 cars long, so their isn’t enough weight at the end of a train to create problems for the part of the train that is in the S. I’ve discovered that many of the “rules” about curves, minimum radius and so forth don’t apply to short trains and/or layouts that are less than basement sized.
I’ve never had a problem with many things others consider unthinkable. I’m building a small layout for my condo with a 15 inch oval, and I’ve been able to run 40, 50, and 60 ft cars with no trouble. 6 Axle road switchers run with no problems what so ever. Many would consider this improbable or even impossible but it works for me!
Beats me…I have one (at least) on my layout, and it has appropriate superelevation through it, too. Short train, long train…doesn’t matter, and a train moving through it and responding to the superelevation looks great.
Nope. Ho scale. You want to know the best part? I’ve modified 70 foot cars to run as well. I didn’t list them initialy because I modified these cars, the others were untouched. It’s like I said, I don’t have the problems many do with small radii. Sure the overhang is a bit extreme, but I can live with that.
I have relied on #6 crossovers on all of my past layouts, and the problems are few, especially if the operator can resist running through a crossover at top speed.
Where problems begin to arise are with multiple crossovers from, say, Track A to Track B to Track C. That becomes too “snakelike” and can more readily lead to derailments. This is especially true on lead tracks heading into large passenger stations with multiple track ladders.
On one of my earliest layouts, I planned a double mainline with a crossover from the outer track to the inner track followed immediately by a single turnout into a yard. My LHS guy took one look at my drawing and suggested that I replace the crossover with a single turnout leading off the outer track connected to a double slip to reach the inner track and the yard beyond. That was a great suggestion to eliminate some tight S-curves.
Spike, the reason is maybe a bit more of a holdover from earlier times when couplers were not so great on OEM, many were mounted on trucks which helped some/a lot, and the diversion angles were more severe than they tend to be on modern layouts. Now, with a lot more body-mounted draft gear, and with longer cars with more fidelity to the prototype presenting a risk, there is still a caution we like to give around here to people whose enthusiasm for certain track arrangements might be a tad optimistic for their choices of turnout geometries and arrangements.
A great many of us like complicated trackwork. They present challenges to pull off, they look cool, and they’re fun to operate. It’s just that we have to know what we’re doing and what the practical limitations are. The fact is that a #3 wye or a #6 DC is not going to confound pretty much anybody except maybe the most stringent high-end brass owners. In fact, maybe well-laid #2.5 wyes will work, or #5 DC’s with well-made brass. But if you get down to sectional track elements and more severe diversions, and with their sharper and sooner-to-come re-paralleling functions to fashion ladders, the longer passenger cars and autoracks and such are going to run into more problems, particularly with more drag resistance behind and ahead of them, and at higher speeds.
Bottom line, I think we have adopted the practice here of pointing out the pitfalls and suggesting that people mock it up temporarily first and do trials. Nothing like solid empirical information.
Thanks to all. I didn’t expect this level of interest in the topic.
I now can have more confidence in using Wye turnouts to exit my continuous loop. We now have a 24" minimum radius everywhere except at the exit of just one Atlas double curved turnout where I felt I had no alternative but to fit a 1/3 section of 22" radius sectional track.
I had not considered the coupler effect or the actual effective radius of a turnout.
The two routes through a crossover came from thinking of a double crossover. What a double slip switch does. I also have one of those and a Shinohara/Walthers single slip which initially I didn’t see the purpose for. Now I have the perfect spot for it.
I bought some new old stock Walthers by Shinohara for no reason other than they seem to be very well made. I’m optimistic about the new Walthers versions. I bought two of those new #6 and they look pretty good. Better than Atlas for about the same price it seemed to me.
So, back to planning as I build…funny that’s still referred to as fast tracking in the design-build construction business.
I agree. In mountain scenery especially, alongside a river, an S bend is inevitable. Model trains look really good on S curves which got me thinking about why not build one?
If you’re talking about an “S bend” in the prototype, remember that the curves are eased, which is roughly equivalent to having a straight section between two non-eased curves.
Also, prototype mainline curves are much less sharp than ours, so they are unlikely to have our kind of coupler/car misalignment problems.
I’m going to use an extreme example of coupler/car misalignment below:
If you place an 89’ flatcar on a 24" radius curve, the end of the car will be 3/8" off track center. This isn’t much of a problem if two like cars are in the curve, because their offsets align. The couplers will BOTH be kicked over 3/8", and the only thing they then have to do is swing a bit in their pockets.
If you place one 89’ flat on the straight track that leads into the curve, and
This raises a question in my mind: how does a modeler avoid “straightlining” thru these S curves? Every so often I see someone has uploaded a picture to Railpictures.net of a freight (usually out west somewhere) that straightlined going thru a curve (granted, not an S curve necessarily). Obviously this remains an issue for real railroaders as well!
Is it simply having the right amount of weight/mass with each boxcar? The right length of train (longer more prone to derail?) Some combination?
I have superelevated my double-track mainline but I’m not running trains yet, and the thought crossed my mind “doesn’t this super increase the risk that my train will straightline?” since I’m leaning the train to the inside of the curve where cars will naturally want to tip.
What radius you need and whether S curves mater and if you can use #4 switches depends on what you run, period. 18" radius and #4 turnouts is what I mainly use on my layout, most cars are 40’ or less and they look fine on 18" radius, if you do 50’ they still run fine but the look is not acceptable to me.
The term is “stringlining”, though “straightlining” does seem appropriate.
Oh, there’s stringlining east, also. Apparently, it’s a favorite passtime on Horseshoe Curve. It usually happens there with centerbeam cars, which when running empty, are long and have a high center of gravity. Not the best choice at the front of a train going uphill on curves. Which is what some wizards are inclined to do.
I first experienced stringlining in 1958, when my Mom bought me some extra freight cars for my Lionel trains. I was running “O gauge”, so the curve radius was 15.5". I’d put together a ten car train, and the cars would fold inwards on the curves. I solved this by buying a box of 072 curves, which had a radius of 36".
No and sort of.
It’s not the weight. It’s the height of the center of gravity. Low is better. A heavy car with a high center of gravity is bad.
Length of train: the longer the train, the larger the “weight” that’s pulling at the back end. Big pull at the back–big pull at the front–oops.
The subject is both very simple and also a bit complex.
The simple part is, if you have a car in a curve, and you pull at one end with a locomotive, and at the ot
The required straight section of track between reverse curves is the wheelbase of the longest car/engine - not the overall car length. Even for 89’ cars the wheel base is closer to 10". A #6 crossover with 2" track spacing is 12" long. Since that’s longer than 10" there’s no problem. Try it with a #4 crossover and you have a potential problem.
This raises a question in my mind: how does a modeler avoid “straightlining” thru these S curves? Every so often I see someone has uploaded a picture to Railpictures.net of a freight (usually out west somewhere) that straightlined going thru a curve (granted, not an S curve necessarily). Obviously this remains an issue for real railroaders as well!
The term is “stringlining”, though “straightlining” does seem appropriate.
Oh, there’s stringlining east, also. Apparently, it’s a favorite passtime on Horseshoe Curve. It usually happens there with centerbeam cars, which when running empty, are long and have a high center of gravity. Not the best choice at the front of a train going uphill on curves. Which is what some wizards are inclined to do.
I first experienced stringlining in 1958, when my Mom bought me some extra freight cars for my Lionel trains. I was running “O gauge”, so the curve radius was 15.5". I’d put together a ten car train, and the cars would fold inwards on the curves. I solved this by buying a box of 072 curves, which had a radius of 36".
Is it simply having the right amount of weight/mass with each boxcar? The right length of train (longer more prone to derail?) Some combination?
No and sort of.
It’s not the weight. It’s the height of the center of gravity. Low is better. A heavy car
No, that is not true. If you place a 12" car on your 10" straight section, the overhang of the car into the curve will offset the car center sideways.
That, too, is a lot of hooey. The 12" you quote is based on the theoretical track lines. A #6 crossover is in fact 16.5" point-to-point.
The length of straight track in a #6 crossover is the distance between frogs. That is approximately 8.25, FAR less than the number you claim to be adequate.
That would depend on the cars and trains you plan on running through it.
I don’t think so. Yes, it should. And yes it kinda does. Maybe. But I’ve been running “plastic” trucks for a long time, and they work just fine.
I DO make my track work properly.
I DO have my superelevations long and gentle.
I DO have long easements.
My trackwork accepts non-equalized plastic trucks just fine.
I do WISH our trucks were fully equalized and sprung, cars and locos both. But I am just not having any problems with the lack of same.
I can certainly see how equalized trucks can adapt to crappy trackwork. I LOVE that. My mainline tracks do NOT feature crappy trackwork.
However.
I do hope to build (again, 'cause I did it previously) garbage industrial trackwork. THERE will be where Sheldon’s concept might prove out. Probably, I will try to make my trackwork LOOK bad, but not BE bad. That being the point of “theatre”.