Please explain Atlas Snap vs Custom line switches

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I am considering building my first layout in years, an HO scale with Atlas code 83 track. I am looking for a small, 4x8 layout. I have only used code 100 in the past.

I am a beginner and want to use Atlas sectional track. I have used it in the past with excellent results. But I am confused about the different types of switches Atlas makes. What is the differences between Snap and Custom line switches and what should I consider in designing my layout? Thanks.



Loveably weird
Basically, a snap switch has the diverging route of the turnout on an 18" radius, while the custom line turnouts have the diverging route straight. The diverging route is the small section of track going away from the turnout at an angle. I would strongly recommend using the custom line series as opposed to the snap switches. Regarding the snap switches, they can best be summed up by Baloo the bear's advice to Mowgli regarding girls in the movie The Jungle Book: "Stay away from THEM, kid. They ain't nothin' but trouble!"
Snap switches will cause nothing but derailments.

Iron Horseman

Well-Known Member
I am a beginner and want to use Atlas sectional track. But I am confused about the different types of switches Atlas makes. What is the differences between Snap and Custom line switches and what should I consider in designing my layout?
Flyboy is exactly correct. A snap switch is designed to fit into some very tight corners when used with the 1/3 18" radius piece of track that comes with it. In general model railroading terms it is about a #3 turnout. The custom line #4 on the other hand is a true North American standard type switch. It is really about a #4 3/4. Any piece of equipment that will go through a 22" radius curve will navigate an Atlas #4. The problem with the Atlas line of track is that they do not make a special curve back to use with the Custom Line #4 to make it come out parallel. When designing I always use another #4 facing it, then when the design is done I replace the 2nd turnout with a piece of flex track.

Avoid the snap switches unless you absolutely have to use them for space considerations. Many items of equipment (especially big modern locomotives) do not like them at all.


Well-Known Member
Staff member
I can attest to the snap switch issue. I have one spot that would take absolutely nothing but a snap switch. I used the snap switch, and I think I would have been much better off with no switch at all. Even some F units have trouble negotiating it.
I've been at this hobby since the 1950's with a couple of layoff's. I have a little (4x5 feet) layout that I am using for fun, practice and testing while getting healthy after a summer of surgeries. Because of the size I used a few snap switches as well as a custom line #4 and an old Atlas/Roco small curved turnout. Also used were a 1/4 circle of 18" radius curves, 5 or so 24" sectional curves and some flex track. I have (and thus am limited to eight wheel deisels the largest being a Kato Alco RS3, and some small steam with a Bachmann Spectrum 2-8-0 being the largest. After a little bit of tweaking, filing points etc all run reliable... including a couple of 60 foot Harriman passenger cars with body mount couplers.

Would I use snap switches if I had a better choice? Probably not however everything is OK now. Keep your track clean and your loco's and rolling stock tuned and you will likely be OK using what you have, or what is necessary.


Well-Known Member
I think that I ONLY have snap switches on my layout (7 on actively used track and three more in yards). It's basically a modified 4'x8'. While some work just fine, others are a crap shoot as to whether my 85' passenger cars will negotiate them or not (I have one car that will run on the snaps without fail as long as I am watching it. As soon as I turn my back, though, the bugger derails). As I look to expand my layout, I'll be looking at other options.


Well-Known Member
Flyboy2610's description of the two types of Atlas turnouts is correct. The question is what kind of locomotives and rolling stock you will use. Shorter rolling stock and locos work better on tight radius curves and Snap Track turnouts (switches). I have been quite successful running ConCor 72' passenger cars on them, but 85' passenger cars will generally not work well. Same is true of six-axle diesels. Generally, 4-axle diesels will work on most anything. Some steam locos with short wheelbases, usually six driver (3 main axles) are okay. Some will stall on the plastic frogs. Hope this is food for thought.
Happy New Year!
Thank you for all of your responses. I decided not to use Snap if I can help it. As I believe what ever layout I build will require also a curved switch, I will use one or two Peco. I have never used or even seen a real Peco but I assume they are good, just very expensive.

I plan to model a present CSX branch line that runs through Highland, NY, not far from me. No passenger service but probably 6 axle motors. I would like to have some car carriers also as I have seen them parked on sidings all over the area. Not sure if they will be too long or not. I don't think I will be using less than 18" curves.


Loveably weird
Actually, Peco turnouts aren't really all that much more than Atlas, and in the larger sizes are more readily available at the moment. They do use a different way of describing them, however. The small radius is generally equivalent to Atlas #4, medium to #6, and large to #8. The geometry isn't identical though, so swapping out an Atlas for a Peco will result in a bit of a mismatch for the rest of the trackage.The plastic area on the frogs is much smaller on the Peco turnouts, so smaller wheelbase locos are less apt to stall on them.
For most applications I would recommend the Insulfrog turnouts over the Electrofrog line, unless you have a specific reason for wanting a power routing turnout. The Electrofrog (power routing) turnouts energize the rails depending on how the turnout is thrown. Suppose you have a siding fed by the turnout. When the turnout is thrown to allow the train to continue on the main line, the siding will be electrically dead, no power at all. When the turnout is thrown to shunt the train onto the siding, then and only then will the siding be electrically live. Power to the mainline after the turnout will now be electrically dead. Electrofrog turnouts require more wiring than Insulfrog turnouts do, but if you have a spot where you need one, they're not too bad. I plan to use all Insulfrog turnouts myself.
I have connected some Atlas track to a Peco turnout, just to see how it would match up, and everything matched up fine.
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Well-Known Member
Peco are good turnouts. The switch points on Peco turnouts have a springloaded throwbar that snaps the points in one direction or the other. The Peco switch machines do NOT have a definite position, but rely on the point spring for positive positioning. I've had less luck with the Peco machines. The turnouts can be manually operated without a switch machine, just by pushing the throwbar. I have a relatively larger layout so I can't reach all my turnouts from my control station. On these I've used a variety of twin-coil switch machines. If I use those that have positive positioning, I remove the little spring from the Peco throwbar. Regardless, I do like the Peco turnouts, especially the double curve type, and use a lot of them. But I also use Atlas both Custom and Snap Switches, where the situation dictates, with the switch machines mounted on top of the surface. (Height varies between 32" and 36" above the floor, for seated operations, and at my age I don't feature crawling under the table to wire or fix stuff!) I'd recommend Shinohara sectional track for some applications, but for your purposes they only make Code 100 and Code 70 rails. I use Code 100 20" radius sectional track in places where I want easier curves than 18" but need to go tighter than 22".


Well-Known Member
Staff member
I pretty much agree with flyboy, other than the compatibility between Peco and Atlas.

What you need to know is this, referring only to Code 83 Track. Atlas' version of the Code 83 track is only a revamping of their Code 100 track. In other words, the ONLY difference between the Atlas Code 83 and Atlas Code 100 track is the height of the rails.

What that means is this - the 'base' or bottom of the Atlas Code 83 track is actually Code 100 and that is not compatible with true Code 83 track. What that means is you cannot use Atlas Rail Joiners between Atlas and Peco (or any other true Code 83 track) because the 'width' of the joiner is too wide to connect firmly or properly. Conversely, you can't use (for example) Peco code 83 rail joiners as they are will be too narrow to connect with the Atlas. Nor can you use Universal Rail Joiners as they are made to true Code 83 specifications.

As we all know, one of the most critical elements of a layout is the continuity of power throughout the layout, the track work. That power is passed from one section of track to the next via the rail joiners UNLESS you have feeders to each and every section of track on your layout. We also know that the majority of issues with track seems to revolve around the turnouts where, if you are using Insulfrog Turnouts for example, you have no power directly connected to the turnout and are completely reliant upon the rail joiners to provide the power to the turnout.

If you agree with the above, in its entirety or even in part, you have to believe that anything that may result in 'poor' continuity of power to your layout is not a viable option and should not be used if you want reliability, and problem free operation of the layout in terms of power.

Yes, you probably can connect Atlas to Peco BUT, at what potential cost? Is it worth 'jerry rigging' something up for the sake of convenience, or as a temporary resolution? I fail to see how what ever worth you may acquire from doing that is worth the potential issues that may arise in the long run.

The answer, therefore, is a simple one. In order to minimize any potential problems (power and connectivity wise) you need to choose between using Atlas Track or another manufacturer of track be it Peco, Flieschmann or any other maker of Code 83 Track, as each other makers Code 83 track is compatible with each other; where as, Atlas Code 83 Track is only properly and fully compatible with Atlas Code 83 Track.

In conclusion, I too found it necessary (in the beginning) to connect Peco Turnouts to Atlas Track. The result? I ripped out all of the 'new' Atlas Track and replaced it with Peco Track. This decision was undertaken due to compatibility issues AND, the quality of track and turnouts of Peco being superior. The choice is yours, but do not try to mix Atlas with any other maker of Code 83 Track. Pick one or the other - definitely not both.
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Well-Known Member
Staff member
No apology needed flyboy. Code 100 is a completely different thing and more than likely is cross manufacturer compatible, regardless of the manufacturer.

I made the assumption that it was Code 83 that was being spoken about ... so I too am sorry for not properly reading the thread.

Mark R.

Custom Painter
In general, even with Customline turnouts, I think you are asking for trouble running six axle engines and auto racks on a 4 X 8 layout !



Loveably weird
If you go up one foot each way to 5x9, you could easily run 24 inch radius curves, giving your 6 axle diesels and autoracks more comfortable curves. 5x9 is the size of a ping pong table, and any home center (Home Depot, Lowe's, Menard's, etc.) could order one for you.

Joe Daddy

C & SF, my obsession
GREAT THREAD Wombat and Flyboy have shared some keen insights into the not so simple task of laying code 83 track. Agree wholeheartedly with Wombat on choosing one brand of track and using it exclusively. Here is a picture of the rail height mismatch Wombat referred to.

Flyboy, Atlas has released a snap switch with a 22 inch diverging track. My choice is either a curved turnout or the snap switch. I'm leaning to the snap for space reasons.

Iron Horseman's tip about using facing switches in planning software to get parallel trackage is also a useful tip.

Thanks men!





Well-Known Member
As I stated above, I've use Code 100 PECO turnouts, as well as Atlas Snap and Custom, and Shinohara (Walthers). Only recently have I come up with a problem with a PECO turnout causing a derailment when a steam locomotive picked the nose of the frog, due to excessive tolerances between the stock rail and the plastic guard rail, which are listed as both HO and OO. The solution was to place a .010" shim on the inside of the guard rail. I understand that PECO is making North American HO-only turnouts, but I've not seen any in the LHS, yet.

I have to agree that the PECO switch machines can be a bit finicky. If you have space under your layout, you could go for stall-current switch motors like Tortise. Of course, Atlas switch machines attach right to the turnout itself. Doesn't look the best, but they do work. I have used both PECO and Shinohara double-curved turnouts, depending on what I needed. Best of luck!
Be careful of Atlas remote snap switches. Exhibit A:

Burned Atlas Snap Switch.JPG

I actually have 16 of these code 83 Atlas remote snap switches on my 4 X 8. I am converting them to ground throws. I am adding a 2 X 8 yard area to make the layout an L shape. I will use another 19 Atlas snap switches with ground throws. I have not had any trouble with 4 axle locomotives and rolling stock that is not to large does just fine. There is a thread here in the forum dealing with upgrading Atlas snap switches which I found to be very helpful. I agree that if I had to do it all over again, I would have went with PECO. But, "I am dancing with the girl I came with". I did look into switching all of my Atlas snap switches to Peco, but I do not have the room on the layout or the skill to make them work without tearing it all up and starting over. is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to - An online railroad bookstore featuring a curated selection of new and used railroad books. Railroad pictorials, railroad history, steam locomotives, passenger trains, modern railroading. Hundreds of titles available, most at discount prices! We also have a video and children's book section. - An online model railroad bookstore featuring a curated selection of new and used books. Layout design, track plans, scenery and structure building, wiring, DCC, Tinplate, Toy Trains, Price Guides and more.