My HO layout (currently framing & plywood deck with a final track plan transferred) will include a hidden double track arc of roughly 180 degrees, with radii of 24+ inner and 27+outer track. The arc will be under a nominal 4" raised area, and the 5/8" plywood above will give about 3" clearance above the lower Atlas flex on cork.
Access for derailed items or track cleaning can be had from underneath and/or (to some degree) from the side. That limited access (when covered atop) will not permit maintenance to the trackage. I will install this hidden trackage arc first, then add the plywood area atop which will have track and scenery.
It occurs to me I need to have a plan for maintenance access to the hidden arc in case of a problem area developing after install and initial testing. Options include making the whole area above removeable or just the needed arc above the lower arc. Either would require disrupting some track and scenery on the top to remove the arc or section. How about somehow making it removeable from the bottom (it will rest atop several joints)??? Or maybe it can slide out the side (the risers might be in the way). Precutting the areas above to make removeable would also require two more splices affecting upper track and likely add some additional risers.
So, some related questions where others experience would help with having a reasonable plan:
a) what’s the likelihood that I will have trouble requiring access for modifications to the track. the likelihood may affect which plan I adopt . I suspect the answer is “plan on it, it’s just a question of time”. Murphy would dictate problems will occur.
b) how do I minimize the likelihhood of problems so at least it’s a seldom or 1-time event; e.g., do or don’t solder the covered and/or adjacent rail joints to help focus expansion movement in more desireable (accessible) uncovered joints,
Now that I’ve had my coffee and taken another look I think the answer is pretty obvious, that side removeability of the arc is the way to go. It didn’t occur to me until typing the note above so thanks for tolerating the lomg question.
I still welcome any input on making the covered track as reliable as possible. I have a goal of making the whole arc from one piece of plywood (which may require a whole additional sheet).
When the LION built his second layout, him made 36" wide tables (very marginal for reaching, especially with an upper level against the wall. Him had staging tracks under that hill. Him thought him could reach the yards from the bottom. This was a non starter, only after I had started and laid tracks.
I got 30 people together, lifted the table and moved it about 18 inches north from the south wall and 18 inches west from the east wall.
That mistake was not repeated.
LION now never goes under the table. It is out of bounds to all but boxes, Union and Railroad Rules do not permit access from under the table, blue flag protection or not.
I too have some hidden track. Before ‘burying’ the track I ran every loco and every piece of rolling stock over the track to test for issues. In fact, I am in that stage now, where all track is complete and I am ready to install scenery forms. I go down every evening and run some trains over the track that will be hidden, with special emphasis on long and temperamental equipment. I did find a couple 'less than perfect sections and made appropriate repairs.
All the above said, I will still be able to access the track from underneath to retrieve wayward equipment or run a rag over the track if need be.
I have considerable hidden track, roughly the back half of a giant folded dogbone, so can speak from experience. Before anything else, consider that hidden trackage hides the trains, too. That’s the biggest issue that you face every time you operate, unlike the maintenance problems that crop up from time to time. In my case, and perhaps yours, too, the sacrifice was necessary and worth the compromises involved. There were no alternatives to getting what I had visible to work other than considerable hidden track.
That said, here’s what I did. My layout mixes standard and narrowgauge via a combination nolix/deck-and-a-half. The NG is up in the mountains, so is what’s on the second level. The hidden trackage, other than some small amount of the NG, is all standard gauge and underneath.
I built starting at the top and planned my access that way. This forced me to design in enough access to lay track from underneath, which coincidentally provides enough access to do maintenance, too. So that’s a way to discipline your design that will aid the use of hidden trackage. I would be very cautious if you lay track first, then build over the top of it. Keep checking to be sure you really can get to every piece of track or you’ll find you’ll have to dig things out to repair in the future.
Don’t push the limits of what equipment will handle. Use wide curve radii, turnouts with a higher frog number, and be cautious/generous about both vertical and horizontal curves and easements.
Something I used to limit damage due to derailments on hidden trackage was to use garage door rubber lipped seal material as a guard against hitting the floor. It’s about 2.5" wide and is designed to be tacked around the perimeter of a closed garage door to keep air from slipping around the edges. I tack one lip to the side of the subroadbed, which leaves the remainder angled out to catch stray cars.
Build to a high standard. Don’t use smaller rail heights than code 83 (in HO), as the extra delicacy will go uns
You may find that adding re-railers before and after the hidden sections a benefit that will only help. Add plenty of feeder wires before closing up the track. Solder the joiners on the hidden track so the expansion and contraction happens on the visible track. Run your track cleaning trains in reverse so the cleaners are before the locos.
LION had some hidden tracks and him mounted a long mirror (the kind that people put inside of their closet doors) horizontally above the sky line so that I could look down into the hidden world and see what was happening in there. Particularly important if you need to do switching in there.
I think I shall put such a mirror above the windows in the library building, since that side of the layout has five levels of hidden tracks. No switching, no train control needed, but just to keep track of my trains. LION runs many trains at once, and when you hear the drag of wheels on ties you want to be able to look up and see where the issue is.
LION has a “Blue Pause Button” (several of them in fact) that will stop the trains the timer and the Railroad Clock. So if LION is not in the tower when a train hits the fan, he can at least stop the railroad.
Reliability. All trackwork should be as reliable as the builder’s ability permits, but hidden track even more so. My netherworld is laid with Code 100 rail for durability, with extra fasteners including screw/washer hold-downs where misalignment would have bad consequences. There are also rerailers in strategic locations, and extra guard rails every place rails cross a joint.
I wasn’t in any kind of tracklaying race, and I started running trains just as soon as the caulk cured. To my way of thinking, I want to be SURE that things will be, and remain, problem-free BEFORE I bury my hidden track under something else - even if the something else can be removed for access.
Maintenance access. My hidden track ranges from easily accessible (removable fascia panels or reach through after hinging a control panel to the horizontal position) to impossible to reach (between main girders, close-spaced joists overhead - and another layer on top of that!) Most switchwork is on removable sub-frames, designed to lift up or drop down and then be removed from the layout for maintenance or modification.
So, how do you clean track that can’t be reached? First off, all my track has been gleamed. Then I run a couple of modified John Allen slider cars, with changeable soft cloth covers over the Masonite pads. That, plus frequent operation, keeps the rails clean. As for heavier maintenance, the answer is, do it right the first time, and make sure it’s right before making access difficult.
Chuck (Modeling Central Japan in September, 1964 - with trackwork as bulletproof as I can make it)
The fact is that anything under tension is fluid over time. If you have cookie cutter sections, spiral ramps, anything that must be kept in alignment with screws and blocks, there will be some movement in the first few weeks, after which things will settle down. So I just found out in my helix. I had built 90 deg curved sections of the ramp and fixed them nicely in alignment with risers and deep-driven screws. I laid track over the joints, and then went back and used a razor saw to cut through the rails so that the sections were truly isolated and ready to take apart if that should ever be desirable. Went away for a couple of weeks, came back, ran a car down that spiral to find it derailing at that cut joint. Looking closely, one side had dropped by about 1/16". What the…??? Needless to say, I had to do it all over, but this time I used more screws for the risers to anchor them better, and I have used the #6 wood screws with small washers over the last two ties before the split on either side.
There is a lot of wisdom in the old rule of running trains for a while after you figure you’re ready to begin scenicking. Things move around, and you must find those trouble spots before you overlay the areas with plywood, trees, other layers of rails, etc. In my case, with a helix, I have it fully accessible with a large boxed center. There’ll be a trouble light in there, too, 'cuz I can bet my last dollar I’ll have to use it at least five times in the first year.
For cleaning, 800 grit paper or alcohol. I never use anything else. I did try auto transmission fluid on my old layout a month before I decommissioned it. I can’t say it helped, and it didn’t really need it, but neither did it hurt anything. The trains ran just fine, no slipping.
For cleaning and electric contact spray (I apply it with a cloth) in places where I can reach is fine. The train will move it into the places that I cannot reach. Whall Clipper Oil, and other such substances also will do this for you.
I feel that building the lower level as a stable section that is easilly removable would be a far better option than trying to gain som access from above. It would be helpful if you could alter your trckplan to gain some added clearance (3" is very tight). The curved cookie cutter section should be decent 3/4" ply and if added support is needed add strips of 1/2" ply to the sides (making an upsidedown “U”). I would suggest using 1/8" Lexan or plexi as guard rails. the advantage of the clear is that you will be able to see the track, truck/ wheels if a derailment… To help with any benchwork movement posibilities and make removal easier, the ends of the section can be installed w/ short pieces of flex/ rail joiners. Removal and reinstallation may require the use of a mirror, but hopefully this would only be nec on rare occasion.
I agree wholeheartedly with what Dwayne posted. Check, check, then check again!! My hidden tracks have foam based scenery over them. Before I added the ground cover, I cut out sections that than can be removed to allow access. Once scenicked, the seams can hardly be seen. Other large areas that are hidden can be accessed from below. To prevent a disastrous fall to the floor, I screwed sections of 1/8" thick plywood the bottom side of the benchwork. They have 4" diameter holes cut with a holesaw to allow me to fit my gorilla hands through.