I am new to model railroading and I am working on an HO layout which will be 4x8 feet. I am currently using a program called SCARM to design my layout. What is the minimum spacing on straights? According to the NMRA, they recommend 2 inches between track centerlines, but is it possible to do a little less and still allow trains to clear each other?
The part that worries me most is the curves, because I am using mostly (if not all) Atlas 18" radius curves due to the small space I have. Part of my layout will have a passing track/siding that goes around a curve parallel to my main track. Will I need that full 2 inches on the curves? The longest car I have is an old Athearn rubber band drive Budd RDC.
Also, what is the minimum switch length on mainline and passing tracks? I was originally planning to use #4, but decided to use #6 instead. Would 4 axle roadswitcher or F unit EMD's be able to handle a #4 with ease or would I face some derailments? Thanks.
Matthew Cheng
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Welcome to the hobby and to the forum. 2” track-center-to-track-center is typical for straight (tangent) tracks. The NMRA S-8 standard does suggest a minimum of 1 13/16” for tangent (straight) track centers, but this is pretty tight.
For sharp curves, you need even more space between tracks. For 18” radius, most people use 2½”, some even wider for longer equipment. This is one of the challenges of the HO 4X8. While it’s handy that plywood comes in that size, it really constrains the radius of curves. If you have the option, building 5X9 or 5X10 opens a lot of possibilities.
#4 turnouts should work with most four-axle equipment, but crossovers will be more reliable with #6s. Note that the Atlas “#4” Customline is actually a #4½, so it’s a bit less sharp than a true #4. (FYI, Atlas Snap-Switches are sometimes referred to as #4s by folks on forums, but they are actually quite a bit sharper.)
Good luck with your layout.
Byron
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Have you consider useing flex track ? It allows you to ''cheat'' a little rather then the absolute of the scetional track
My Atlas Custom-Line Layouts book shows how to combine 18" and 22" and a short piece of straight to make three different curves 18", 20 1/4, and 22 1/2" radius. It appears that they have 2 1/4" spacing. With slight modifications you could use two of the three shown and have two curves side by side with more than 2" center spacing.
Good luck,
Richard
Walthers has #5 turnouts, so you could split the difference. Like Byron said, try and cheat a bit on the dimensions, it will make life so much easier. Instead of a sheet of plywood, use 1" x 4"s and build an open grid. You can then use foam or ply on top. I bought some 9' long fir 1' x 4's this week at the lumber store for $1.83 a piece.
You can also use spline or cookie cutter for the roadbed leaving the grid to be filled in at a later date with the scenery. Going 66" across will let you have decent curves.
Just tell the boss you are going to build your layout in the corner, just don't tell her how far out from the corner you are coming.
Here you can see where I used spline on the open grid. You can have trains running pretty quickly, just put a sheet or cardboard down in case of derailments.
Brent
"All of the world's problems are the result of the difference between how we think and how the world works."
The thing is, I got a TON of old track and switches at a model train show for around $5 a bucket. A good portion of it I will probably end up using on my layout. I do not really want to have to buy any new pieces of track (I have mostly 9" straights, 18" curves, Atlas snap-switches and a few Customline turnouts). Are #4 switches acceptable on mainline tracks or is that too tight?
But what if the tracks, structures and tunnels are already in place????
This contrtaption was made by the New York City Transif Authority. They cut in half a 60' car and extended it to 75' and gave it the contour of the new 75' subway cars. They then ran it through the tunnels to see where it would fit and where it would not. If any of the fingers touched the wayside, the wayside had to be altered to accommodate the new vehicles, and if it could not be altared, then the new cars sould not pass through those tunnels.
Most frequently the issues were add-on conduits, misplaced signals and stuff like that. The only real problem was the curve comming off of the Williamsburg bridge. The train could pass either way on either track without problem, but if TWO such trains tried to pass each other on that curve the conflick would be rather entertaining. Thus the 75s could not operate on the Jamaica line.
This car is no longer in the fleet, in fact while there are still 75' cars running on the subway, they will not be reordered, all future cars will be 60' on the IND / BMT and 50' on the IRT.
ROAR
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Here there be cats. LIONS with CAMERAS
Trainzguy2472 The thing is, I got a TON of old track and switches at a model train show for around $5 a bucket. A good portion of it I will probably end up using on my layout. I do not really want to have to buy any new pieces of track (I have mostly 9" straights, 18" curves, Atlas snap-switches and a few Customline turnouts). Are #4 switches acceptable on mainline tracks or is that too tight?
Anytime you have to work with "what you have" it will be hit or miss. I would suggest setting up test sections. #4 switches will have to be taken at a slow speed regardless of where they are placed on a layout and some equipment will not go through them at all. It is the same with tight curves, that is why trying to sneak a few extra inches in on the build is a good idea.
If you are limited by what you have, test, test, test.
Two inches is suggested, as others have correctly noted. Anything less can create issues with overhang, etc. You also can cheat by not having two trains running that close to each other or slow enough to avoid any issues.
Curves do require more distances. Perhaps test the curves of see online how others can bypass the suggestions.