I am playing with my layout on AutoCAD (I have it on my laptop for work and don’t want to purchase something else)…and am wondering what is an optimum turnout that’s easy on the train yet doesn’t take a real long radius? #4 is tighter and #6 is wider, correct? I am going to be using mostly modern style diesels and will have an Amtrac passenger train too. Also some steam because my 5 year old likes the “Polar Express”…. My layout is a smaller one, approx. 6 x 13 feet overall and I will be sharing it with a 4 lane HO slot car track. My train system will be within 30 inches of an edge so that I can reach a de-railed train, and I can get a de-slotted slot car with a pair of my extension grippers.
I am also interested in elevation…2% vs. 3% and 4% inclines. I don’t want too steep of an incline and do not know how to gauge what is ok vs. what is too steep.
My layout will be simulating the Smokey / Blue Ridge Mountain area (an Eastern TN, Western NC, and Northern GA).
I am looking for that happy medium and hoping for any feedback. Thanks!
Mike/Nightshade
P.S. How long is an 83’ passenger car in HO scale? Sounds too long for what I want, but what do I know…
Hi. It is usually a good idea to have the widest curves and widest turnouts that match them because most of us will want items to run on our layouts that we don’t currently contemplate having in the foreseeable future, and those items tend to be bigger…whether steam or six-axled diesels. So, plan for future needs.
That said, #6 turnouts for sure, and a few good #8’s will mean less to change out in the future. Keep your #4’s, if you have them, for the yard and close industrial switching. Of course, your larger stock and engines will not be able to negotiate those smaller turnouts…possibly. Would it be possible to get to a local club and see for yourself?
The lower the grade, the longer the run it will need in order for you to build in bridges and overpasses with sufficient clearance for any trackage below them. On the other hand, the steeper the grades, the harder your engines will have to work. That means smaller trains, doing it in two stages (the prototypes avoided this like the plague), or cutting in helper locos. If you don’t have the other locos, no matter the reason (cost, space, whatever), you must keep your grades below 2.5%, plus or minus 0.5%. This is not hard and fast because, like everything else, it depends…(how well you can lay your track, how steady the grade really is, your skill at building transitions into and out of the grade {reaaalllly important for larger steamers}, how heavy your locomotive is, the quality of your rolling stock and their couplers and wheel-sets, etc.)
Your passenger car would be near 11.5", plus couplers.
Part of my layout is logging. For those areas I use 4% and 16" curves and run my Climax and Shay. For the rest I have # 4 and 18" and 3%. I have to double head up the grades with a long train. All of my stuff runs on this, but my articulates are smaller and I don’t really have diesel. #8 and 24’ are nice if you have the room, but I like what I have.
Note that this is Recommended Practice, and almost no commercial turnouts I know of follow this very closely. For this reason, I recommend using one of the model railroad track planning software packages instead of AutoCAD. They have libraries that include fairly accurate descriptions of available commericial turnouts. Two of these packages - RTS and XtrakCAD are free.
In any case, the closure rail radius is a fairly good way to match the turnout number to the curves being used. The closure rail radius is usually the sharpest curve in the turnout. One can go a little smaller with the closure radius because on normal (not curved) turnouts it is almost always shorter in length than any wheelbase you are worrying about. The straight portions on either side provide easements to the closure radius and make it effectively bigger.
Because commerical turnouts do not follow the NMRA RP, the RP is only a guide. For instance, Atlas HO Custom Line #4 turnouts really are about a #4.5 with a closure radius of just about 22". Some Peco turnouts and the Atlas Snap Switches have curved frogs and a continuous curve throughout. The Atlas Snap Switches are 18" radius, I don’t know about Peco.
On curved commercial turnouts, if the frog is not curved, the closure radius will be considerably sharper than the NMRA chart shows for a given frog #.
Closure radius is NOT the turnout substitution radius. The effective substitution radius is much bigger due to all the straight portions of the curved leg.
As far as grades go, what is OK is up to you. A 2% grade comes close to cutting the number of cars a loco can pull in half. When you get to 4%, you are looking at 25% of level pulling capacity, perhaps even less. Above 5%, you will probably have to test each locomotive indivi
I’ve found John Armstrong’s book Track planning for Realistic Operation to be a great help–in addition to lots of detail on the things you’re asking about (turnouts, curves, and grades) he’s got a lot of guidance for the whole planning process. This is a book well worth the cost.
One of the biggest guidelines in John Armstrong’s book is to TEST YOUR EQUIPMENT. You might find that your favorite locos, hauling your typical length train, can’t even make a 2% grade. Or you might find that they can handle 4%. There’s no real ‘rule’ for grades, what works for one person may not work for you. Hence the testing. All you need for grade testing is a straight board and some track, and some blocks to try various elevations.
Keep in mind a grade on a curve is effectively steeper than the same grade on the straight. The addiitonal friction of the curves puts more load on the locomotive so it cannot pull as many cars as it could ont he same grade % with straight track.
If you have not read John Armstrong’s book “Track Planning”, I strongly recommend buying a copy and studying it carefully. His advice will always apply to any layout. As someone previously advised, YOU MUST test your engines/trains before setting the grades-otherwise, be prepared for a lot of disappointment. The same holds true for turnouts-set up a test track and try out the various types-except for the #4s, you can always use the track and turnouts on your layout. Bob Whitten bobandbonnie@earthlink.net
I use #6 switches and 30" minimum radius curves. Most of my rolling stock is 40’ or smaller, with a few 50’ cars in the mix. Passenger cars are about 80’, and run fine. The era is 1930s-1940s, so locos are Heavy Mikes for the most part, with some smaller stuff. Larger locos also should be okay, but I don’t expect to add any articulateds bigger than a Yellowstone.
My maximum grade is about 1 3/4%. Any more and the steamers lose significant hauling power (they won’t pull many cars up the hills).
Thanks to everyone for their input. I will definetly purchase Armstrong’s book.
I was wondering about the elevations. I don’t have to worry about any of my old engines…I checked and none of them have a slot for a decoder, so I’ll have to get new ones.
I plan on going with slight inclines. No need to act like a billy goat and run straight up the hill. My layout will have my track mostly near the outside of the 72" table. 1. So that I can reach a derailment and 2. Because I will also have a slot car track near the middle…so the larger radius curves will be easier to use in the installation.
A newer engine doesn’t guarantee good pulling power. I have a beautiful (expensive) Atlas MP15DC with sound. It’s one of my absolute favorites, but it’s only good for 3 or 4 cars going up my 2.5% incline. I also have Atlas GP-38s that would pull my refrigerator up the hill. When you get ready to buy, check with the folks here on pulling power for the specific locomotive you want.