So I'm drawing out my HO track plan on plywood (yes I'm actually starting to build my layout) and I have some questions on track spacing.
I have one section where a double track mainline needs to run along the back edge of the benchwork. Some testing with flextrack and a variety of cars shows that I should be able to squeeze these down to 1.75 inch track centers. Mind you this is a static test conducted by rolling cars back and forth to see if anything hits. This is a straight shot of about 8 feet in length. Looks ok to me but has anyone else gone this tight? My major problem is keeping the benchwork depth reasonable, there is a major LDE in the foreground and adding depth to the benchwork will push me over 48" deep.
Second thing is a couple curves, 28 and 30 inch radius which should give me 2" track spacing. Aain seems ok to me but I will have some 89 foot passenger cars rolling though here. I don't have enough 89 foot cars to thoroughly test this so any practical advise on this? Going wider here is pretty easy but I don't want riduculus track spacing.
Modeling the Cleveland and Pittsburgh during the PennCentral era starting on the Cleveland lakefront and ending in Mingo junction
ruderunner,
In my opinion, you are flirting with disaster. I could not get away with 1.75 inch centerlines on my double mainline. I would shoot for 2.00 inch centerlines. That's what I use. Incidentally, that is what is used on double crossover tracks in HO scale. On curves, especially on 28 to 32 inch radius, I would shoot for 2 1/4 inches. That is what I use on my double mainline which has the outer curve at 32 inch radius and the inner curve at 30 inch radius.
Rich
Alton Junction
Ruderunner,
The NMRA Standards for track centers in HO are: 2" on straight track, 2-1/4" on 24" radius, and 2-1/8" on 30" radius. The chart I have doesn't list a 28" curve, but you can safely assume it's about 2-5/32". This means that most manufacturer's equipment will clear passing trains on the parallel track.
These are standards, and you're free to ignore them if you need to, but at the risk of having things go bump in the night.
Pushing the straight tracks at the rear of your layout closer together doesn't sound like a problem if you haven't found anything with a clearance issues. OTOH, I would be very careful on the curves if you're running 89' passenger cars. They're vary unforgiving.
Connecticut Valley Railroad A Branch of the New York, New Haven, and Hartford
"If you think you can do a thing or think you can't do a thing, you're right." -- Henry Ford
Go down as low as you know is safe from real trials, and then go as generous as you can and not compromise your design. The need for space or configuration is important to you, obviously, and there's no real reason to avoid cramped quarters. Just be aware that it is that much more critical for you to have superior tracks laid down along those places.
I am speaking about the tangents. Curves are tricky. You may want to establish a go/no-go spacing for each curve because no two are going to be identical unless you are using sectional track and lay it perfectly. Just keep one thing in mind...every time you introduce anything that wasn't tested beforehand, you run the risk of unintended contact with at least one part of the new model and something that existed/exists on your layout now. Happened to me a couple of times, so I know.
Crandell
Keep in mind also that you have to consider that trains do often derail. The spacing should give you some play to avoid collisions when it happens.
Springfield PA
! 3/4" is too tight. Just the 'wooble' of some cars will cause a problem. I would not go below 2" on any tangent trackage. For curves, the NMRA has a very good table at the following web link:
http://www.nmra.org/standards/sandrp/s-8.html
Note that for a HO 32" radius curve, they suggest 2 1/2" centers for the longest equipment. I have a 30"/32 1/2" curve and have not had any problems , so I suspect that that table is pretty accurate. The overhang on long passenger cars is pretty severe. And large articluated steam engines have know to be 'street sweepers' when running on the inside track of double track main lines!
Our club is a little 'overbuilt' All tangent track centers are 2 1/2", and curves have 3" centers(30"/33") - so far, no problems over the past 5 years of operation.
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
ruderunner ....Some testing with flextrack and a variety of cars shows that I should be able to squeeze these down to 1.75 inch track centers.... ....Second thing is a couple curves, 28 and 30 inch radius which should give me 2" track spacing. Aain seems ok to me but I will have some 89 foot passenger cars rolling though here. I don't have enough 89 foot cars to thoroughly test this so any practical advise on this?....
....Some testing with flextrack and a variety of cars shows that I should be able to squeeze these down to 1.75 inch track centers....
....Second thing is a couple curves, 28 and 30 inch radius which should give me 2" track spacing. Aain seems ok to me but I will have some 89 foot passenger cars rolling though here. I don't have enough 89 foot cars to thoroughly test this so any practical advise on this?....
For me, the NMRA Standards and Recommended Practices are always a good reference point. I would not deviate from them unless I have enough testing to prove to myself that the deviation will be successful.
For track spacing, NMRA S-8 Track Centers applies (http://www.nmra.org/standards/sandrp/s-8.html. Note that this is a standard and not a recommended practice.
For HO straight track, the standard says 1-13/16 inches, which is 1/16 inch more than your 1.75 inches. I suspect the 1/16" will be critical in only a few cases of locomotive or car details. But if you happen to be one of those cases....Cabs on long steam locomotives tend to yaw somewhat when backing up - those will most likely be your problem areas. You might also consider the tolerance to which you can lay and maintain your track spacing. You may have set a standard of 1.75", but are there places along the 8ft where it snuck down to 1.65" during installation or ballasting? Easy to do with Atlas flex track. That's your decision - it's quite possible that you are more precise in your track laying than I am.
For HO curved track, the standard does not address full length passenger cars or other 80ft+ cars on less than 32" radius. But at 32" radius, the minimum spacing is 2.5". My guess is that you will want at least 2.75" to be safe. Again, the critical point will be backing when the slop in our model wheel sets encourages the locomotive cab or passenger car end to push out more than normal from the track centerline.
my thoughts, your choices
Fred W
What do you plan on doing with that extra quarter inch, anyway?
Dave
Just be glad you don't have to press "2" for English.
http://www.youtube.com/watch?v=zQ_ALEdDUB8
http://www.youtube.com/watch?v=6hqFS1GZL4s
http://s73.photobucket.com/user/steemtrayn/media/MovingcoalontheDCM.mp4.html?sort=3&o=27
Contraran reporting for duty, Suh!
The tangent tracks of my two back-in staging yards are 45mm on centers - just a gnat's eyelash wider than 1 3/4 inches. I avoid sidswipes by carefully peeling off with long, gradual easements and avoid parking anything on the curves leading to the turnouts at the yard throats.
With all due regard to NMRA standards, they were written at a time when tracklaying techniques were a lot coarser than they are now. At that, they were, and are, wider than the prototype I measured back in the '50s (NYC, 14 feet, or 49mm in HO.) I don't know if Tim Warris is using prototype spacing for the tracks of his CNJ Bronx Terminal. If he is, the tangent tracks are only 37mm on centers!
Granted that those examples came before 89 foot auto racks, humonguboxes, Schnaebel cars and wide-vision cabeese. That doesn't render them invalid. It only identifies the kinds of things that would be embargoed from the Bronx terminal if it existed today.
As for derailments on tangent track, if one ever occurs it's a symptom of either defective rolling stock or seriously deficient tracklaying. I consider such a derailment on my layout to be about as likely as an asteroid collision.
Chuck (Modeling Central Japan in September, 1964 - with track centers determined by experiment, not NMRA fiat)
I run several articulateds and visiting 85' passenger cars on the small-medium layout I'm still laying track for.
IF you have the room for 3" track separation (I have 30 and 32" radii with 24" adjacent track curves.) I heartily recommend that separation after testing with Cab Forwards, Big Boys, etc. as well as the passenger cars. The tiny bit of extra room is very comforting with derailing, car rocking, tunnel portals, etc.
If you're planning on holding ops sessions that extra room is, again, comforting.
It also has the benefit of proving a touch more trackside detailing to make up for other perceived loss
of "real estate". I personally would not feel comfortable running these big locos on anything less than 2.75" track separation. On the other hand I'll have to make some custom tunnel portals or combine several single track portals to deal with the 3" separation of tracks.
Raised on the Erie Lackawanna Mainline- Supt. of the Black River Transfer & Terminal R.R.
tomikawaTT Contraran reporting for duty, Suh! The tangent tracks of my two back-in staging yards are 45mm on centers - just a gnat's eyelash wider than 1 3/4 inches. I avoid sidswipes by carefully peeling off with long, gradual easements and avoid parking anything on the curves leading to the turnouts at the yard throats. Chuck
Chuck
Well, now that Chuck has thrown down the gauntlet, for the non-mathematicians in the audience, 45mm translates to 1.7716535415 inches to be precise. It should be noted that 1.75 inches is the equivalent of 44.45 mm.
I would say this. Anything under 2.00 inches can be problematic, even in the absence of longer or wobbly freight cars, unless you track laying skills are very precise. Any wavering from an absolute straight line can lead to problems.
steemtrayn What do you plan on doing with that extra quarter inch, anyway?
Touche !
In earlier days 13'-0 seemed to be the normal minimum for main track centers, which scales to 1.8" in HO. But usually even there the centers were at least a few inches wider. New construction today will use wider centers, sometimes much wider. Equally, I did find a short subdivision on the D&H that was built with 12'-0 centers. I have to assume their Challengers were prohibited, and likely other equipment too.
As others mentioned, curves need to be much wider to provide clearance. The prototype increased them by 2" per degree of curve, and common model curves can be 30 degrees and up. Another thing to bear in mind is that the models themselves may be slightly wider than prototype, especially if grab irons stick out a little, or truck centers were adjusted to clear coupler boxes.
The NMRA numbers are the best guide. Track centers wider than that make operation easier but the gap between passing trains is too obvious for my own personal taste, acceptable for today's scene but not the earlier eras. It depends where your own priorities lie. Some degree of compromise is inevitable whatever your modeling style may be.
John
You mention being pushed over 48" in depth. Hopefully you have access from both sides. 30" - 32" is usually the recommended maximum reach, depending on layout height, your height and amount of scenery you have to reach over. If you try to reach a derailment at the back side of a 48" layout it will spell disaster for a lot of scenic elements on the front edge. Hopefully you can walk to the back or have an access hatch to reach things.
Good luck,
OK so my curves are too close, I'll shoot for 3" spacing there. May move the centers of the curves or enlarge the outter radius, whichever looks better.
As for the benchwork depth versus track spacing, this is kind of a comlicated area. The foreground is a model version of Whiskey Island ore docks which is 3 loops of track nested inside each other, then near the backdrop is a double track mainline and a hidden track to staging. Total 9 tangents on this 8 foot stretch but 6 of those are looped on 16, 17.75 and 19.5 inch radius. For the sake of construction and future portability I'd like to keep this on one 4x8 sheet of plywood though frankly going as much as 60" deep would allow for 2" track spacong and wider radius curves on the loops. It just gets big. Yes I will have an access hatch to reach the rear tracks and the hidden track will be behind some removeable building walls.
Currently this will be going along the basement wall but as the layout grows it may end up as a peninsula. That's part of the reason for portability/sectional construction, fitting everything I want may require rearranging the sections.
If a 5'X9' sheet will provide you with better radii and not crimp your scenicing as much, it might be worth it.
As long as you can get the layout out the room's doorway on it's side (building height, mts. ,etc.) or it doesn't have to conform to a modular club's dimensions, it's something to consider anyway. But, you probably already have...
If you're radii are that small, it may not make a difference for you. When I moved up to a 5X9 from my 4X8 I was actually kind of amazed how much it freed me up. There was a huge difference between 18" radii and 22" and how well everything ran in comparison. (Makes buying larger locos possible if that's what you'll want later.
Now I'm up to 30"/24" on average with an 8'X17' walk in design - it's still not as large as I'd like for a mainline. If your layout is an industrial area/district only, the radii you've chosen may be just fine and look prototypical. The larger radii probably are most useful for some continuous running on the mains though.
Hope the sheet ply thang isn't too off subject. They make 5'X10' sheets too ;-)
Yep primarily urban industrial switching. With the exception of the Whiskey Island loops my radii are 18 or larger and for the mainlines I'm trying to stay close to 30.
A 4x8 is about the largest I can get into the basement without deconstructing the drop celing and even that won't get me much, maybe 4.5x8.
For laying track to the minimum 1 13/16" (or less), I suggest making a couple of gauges from strip wood notched for the separation. This will keep the distance constant and correct.
The curve separations are for engines and/or cars on adjacent tracks. For industrial tracks you can use less as long as you don't have cars and/or engines on both tracks at the same time during operations.
Enjoy
Paul