Why a Wye

[BATMAN]

A thought just occurred to me as I'm building my first large layout. I have three of places where my single mainline will branch into a double or triple main. Should I use a wye or something like a #7 or #8 turnout? I have never used a wye on past layouts. Thoughts? And thanks for the help.

[selector]

I don't see why not, but it really depends on the space you have for the wye.  They are large turnouts, but I use one gratefully at the throat to my modest two track yard...sorta three, actually, if you count the arrival departure that runs right past the depot's platform.   One thing to consider, and I'm not expert or historian, but if something goes wrong with a wye turnout, it could prohibit, or inhibit, passage to any of the three parallel tracks while maintenance is taking place.  Just a thought, and it may have been a show stopper for some railroads.  Dunno.

[tomikawaTT]

A thought just occurred to me as I'm building my first large layout. I have three of places where my single mainline will branch into a double or triple main. Should I use a wye or something like a #7 or #8 turnout? I have never used a wye on past layouts. Thoughts? And thanks for the help.

A "Wye" or double-curve turnout is usually used where both branches will keep on curving away from each other.  Using it to split a single track main into two parallel tracks can lead to rather nasty S-curve problems.  OTOH, it can be used where a center track splits to end a siding or spur between parallel, widely spaced tracks.

In my experience, whenever a single track spreads out into a number of parallel tracks they are connected with standard-design turnouts.

Chuck (modeling Central Japan in September, 1964)

[ndbprr]

In real  life from what I have observed it depends on the number of trains that need to traverse which route.  It could add to operations to have a train only have one route from a branchline and then run around to go the other way.  It could also be a pain.

[Gandy Dancer]

I have three of places where my single mainline will branch into a double or triple main. Should I use a wye or something like a #7 or #8 turnout? I have never used a wye on past layouts.

To me I would not use a wye where the line is going from single to double track.  With a wye, both routes have to have a curved section.  With a normal turnout at least one route can be straight through.  For the places where it goes from double to triple it would depend on the configuration.  If the third track is in between the original two a wye makes perfect sense.  If the third track sprouts off one of the mains like a normal siding I see no advantage of using a wye.

All of the above assumes the transistions are on straight track.  If these transistions are occuring in a curve, the wye could very easily introduce a highly undesireable double "S"-curve situation.

[selector]

In my case, the wye comes right after another #6 turnout, and is on that turnout's diverging route.  However, I placed 8" of flex between them to allow me to orient the axis of the wye turnout to my parallel yard tracks.  Then, on both diverging routes of the wye, I also added a slight curve section of flex to get me to the point where I could lay those three routes in parallel...with about 3" of centre-to-centre separation, somewhat more than ideal for the prototype.

I took this just now with flash, sorry, but you can hopefully follow me.  The wye requires wider separation, unless you can get a #8 or higher, but it will be loooooooongg.

[BATMAN]

Thanks Selector. That photo was just what I needed to see. It gave me perspective on the whole thing.

[loathar]

Selector-Isn't that a 3 way?

The only time I've seen wyes used (other than in yards) was to make a short passing zone mainly for street car type use. Other than that, it's usually standard turnouts.

[Gandy Dancer]

Selector-Isn't that a 3 way?

I must be blind.  I see a three way but don't see any wye turnouts in that picture.

[MisterBeasley]

I've got one wye turnout on my layout, at the entrance to a 2-stall engine house.  I see it as an eye-catching, interesting piece of trackwork.  This is a short Peco wye, and probably wouldn't be appropriate on a main line, but a longer wye might be fine.

If the track paths flow naturally to a wye, then use it.

[d van]

A wye can come in handy if space is a issue. They are shorter than the same number standard turnout. I had a 3 wye '2 mainlines into 3' on a former layout that worked very well.

[selector]

Selector-Isn't that a 3 way?

The only time I've seen wyes used (other than in yards) was to make a short passing zone mainly for street car type use. Other than that, it's usually standard turnouts.

Er, uh, yeah it is a three-way.   Where was I...oh, yeah, about the wye....(is it hot in here?!)....

Anyway, the point is that the effect will be the same; you will have to add flex to the diverging ends in order to avoid a nasty S-curve if you were to join those diverging routes to another turnout's diverging route, or to get parallel tracks.  I wanted to show that a wye/threeway-with-a-wye-on-the-extremeties can work, but it needs work.  And a longer one with a higher frog number will take up more space, although it will need less of a "righting" to bring its diverging routes parallel.

What was I thinking?

[BATMAN]

Don't bug selector. There is a big storm heading his way and he will probably lose his power for a week or so, and what is a model railroader to do with no power??? This is probably where his mind is at. (the impending lifelessness his layout is about to endure)

[dehusman]

 A wye is used where there needs to be a diverging alignment from both sides of a switch.  They are often used at the ends of sidings for very high speed lines.  They are also used at the ends of center sidings, as well as in yards.

The thing to remember is that the wye doubles the effective number of the frog.  If you use a #4 frog in a wye (or equilateral) switch it makes the angle of divergence for either route equivalent to a #8 turnout.  So using a #20 frog in a high speed turnout makes either route equivalent to a #40 turnout.

Dave H.

[WCfan]

A thought just occurred to me as I'm building my first large layout. I have three of places where my single mainline will branch into a double or triple main. Should I use a wye or something like a #7 or #8 turnout? I have never used a wye on past layouts. Thoughts? And thanks for the help.

A "Wye" or double-curve turnout is usually used where both branches will keep on curving away from each other.  Using it to split a single track main into two parallel tracks can lead to rather nasty S-curve problems.  OTOH, it can be used where a center track splits to end a siding or spur between parallel, widely spaced tracks.

In my experience, whenever a single track spreads out into a number of parallel tracks they are connected with standard-design turnouts.

Chuck (modeling Central Japan in September, 1964)

Actually in just out side of Winona, on the Wisconsin Side. On the  BNSF line along the Mississippi they used a wye when merging the double track (parallel double track) into a single. I think they use this for high speeds. I'm not sure.

[tomikawaTT]

Actually in just out side of Winona, on the Wisconsin Side. On the  BNSF line along the Mississippi they used a wye when merging the double track (parallel double track) into a single. I think they use this for high speeds. I'm not sure.

Entirely probable.  It's also entirely probable that the frog number is somewhere around 16 - not exactly practical for normal model railroad practice.

Chuck (modeling Central Japan in September, 1964)