My benchwork and plywood subroadbed is all completed, as well as most of my track. This is an expanded version of the Virginian layout.
I would really like to add a bridge to the layout, but am hesitant to cut the subroadbed I have in place. The two main reasons are 1) it’s on an incline, and 2) it’s curved. I took great care in making sure that the incline was all one continouse piece of plywood to avoid having kinks, etc in the track. I feel like it’s a sensitive part of the track and I’m reluctant to cut it.
So, I was wondering if it is possible to by some sort of bridge sides - either girder or trestle, cut down the subroadbed right up to the track, and then just attach the bridge sides. I assume it is possible to do this, but the real question is, is it possible for it to actually look good, and like a real bridge?
If I do make a cut, I am thinking about putting in something like this for example:
The other issue is that I have not yet laid any track or run any trains yet on this portion of the layout. So I’m worried that if I cut the section out, and then have problems, it could be more difficult to raise or lower the track if it is not one piece. Should I just complete the track as if there is no bridge, and then when ready, cut out the track and everything?
Below is a pic of the area in question:
My other idea was to put the bridge in this straight section, and have the fascia and scenery drop below table level. I think this could pretty neat and may be simpler to do. Again though, not sure if I should cut the track, or try to just attach the bridge sides. Any advice is much appreciated!
You could build the bridge you want (your first photo) by cutting the plywood roadbed narrower, but it would need to be narrow enough that the girders could be situated below the rails, and not below the tie-ends. It would also need to be narrowed in straight segments, since the girders cannot be curved.
Micro Engineering offers girders in 30’ and 50’ lengths and your curve looks fairly tight - the tighter the curve, the shorter the girders have to be: otherwise the path of the rail won’t coincide with that of the girders.
The ME girders are detailed on both sides, as they’re meant to be used in built-up form with crossmembers, but if you want to attach them to the trimmed roadbed, it would work better if all of the detail on the back side of all girders was removed. This would leave a flat surface, which could be glued to the segmented and narrowed roadbed using contact cement. An added benefit of removing that detail is that the wood roadbed could be left wider (and therefore stronger) than it would be if you had to accommodate the extra width of the full-width girders. Paint the top of the remaining roadbed black to disguise its origin.
My layout is also on 3/4" plywood subroadbed, which made it easy to raise it as a smooth incline. After it was in place, I determined where I wanted to place bridges, then used the actual girders atop the roadbed to calculate how many were needed to bridge the area - this calculation should be done only for the outside (longest side) of the curve. For the inside, the same number of girders will be needed, but most or all will need to be shortened.
Once I knew where the ends of the bridge would be located, I cut out the roadbed, flipped it upside down, then built the bridge (using mostly ME parts) also upside down, directly on the underside of the section of removed roadbed - using this as a pattern kept the curve in proper alignment.&n
Both areas you are considering will accept the steel viaduct. Cutting out the subroadbed is the way to get the best looking bridge. You could cut the subroadbed narrower and glue the girders to the sides, however the subroadbed appears to be3/4" ply and I don’t think you will like the appearance as it will have to be a ballasted deck. Additional sides/ ballast stops will be needed, best bet is to cut out the section and install. Before cutting you should make sure there is a frame connection to tie the 2 risers. The straight section will be far easier to do. The curve appears to be 26-28" and special work is needed in constructind the viaduct as you can only use 50’ girders (min tie overhangs) and they will need to be mitered to the curve from a template.
The reinforcing of the benchwork is advised as not to allow any “spring” or future movement. That straight section can be done by cleating the risers and placing a plywood base, this can also act as the foundation for the bridge towers or piers.
Select the bridge and calculate the actual distance and final position before cutting. Additional wood risers can be placed to position your abutments exactly where needed for the structure. These risers can also be notched if nec for the bridge shoes.
This is a modified ME tall steel viaduct starting w/ the 210’ kit, other offerings from ME have the girder sections you are looking for.
Maybe a lot of “overkill” in the benchwork and risers, but you could step the piers to the slopes of the scene if desired. I plan to “veneer” those sub abutments, the reason for the bridge shoes “hanging” off the shoe shelf.
If you opt to not cut out a section of the plywood benchwork, then I too would vote for trimming it considerably. As others have mentioned, you could cut and install (with some adaptation) a viaduct style bridge. Using sheet and strip styrene, it is not difficult to scratch build plate girder sections for bridge sides. Make paper templates to size them to proper lenghths.
If you are modeling a railroad that has been around for a while, you might want to think about cutting the bench work and installing a trestle to span the gap. It is easy to hide a pair of Plastruct “H” beams under the rails to stiffen the structure. Histroically many trestles curved and/or changed elevation as needed to fill gaps that were not easy to span.
I would definitely make the cut and put in the bridge. You clearly have the skills to get the job done, and it will be a much better scene with the bridge in place.
Do it now. The only concern I would have at this point is if the plywood you will be removing has longitudinal forces along it, and it’s best to find that out now so that you can correct for it while everything is still just benchwork.
MisterBeasley - what exactly do you mean by “longitudinal force”? When I first built up the incline, there was some natrual superelevation because the entire climb is one piece of plywood. Is this what you’re referring to?
I’m honored that you said “I have the skills to do it” - I guess I’m lacking the confidence. This is my first layout and I’m learning a lot. So far it has gone relatively smoothly - I guess I’m afraid to ruin my record! I suppose any problems that popped up are fixable, and without too much difficulty, so I will probably go for it.
Should I lay some track first without the bridge and at least run some trains up it a few times to make sure the grade is ok, etc.?
Also, do you think the viaduct I posted above is a good fit for this space? I think it looks more dramatic than a girder bridge and I like the look. It also says in the product description that it can be made to work with curves, so it seemed like a good choice.
I would build the bridge on the straight section, your second option. I would also cut the roadbed, judging from the pictures of the benchwork, you have more than enough skill to do it rather easily.
Cutting the roadbed out from under the briidge location shouldn’t pose a problem. Here’s what I do…
I add the riverbed (or whatever goes at the bottom of the scenic feature the bridge crosses) with plywood or other scrap, cut to extend under the entire bridge span. I ensure this piece is secured to both the benchwork and the roadbed that is to remain, typically adding some extra risers between it and the roadbed, and more risers if needed between it and the benchwork. The goal is to provide something solid to prevent the roadbed from moving around the bridge.
The roadbed here is hardboard spline, but the principle is the same. There’s an extra riser on both ends of the opening, while the streambed is elevated above the benchwork on more risers, and also attached to the roadbed risers. With these steps complete, I can then cut the roadbed and be nearly certain it will remain in alignment. Both of the locations pictured are on a grade, and of course the last one is on a curve.
When your sceneery is complete, the additional support structure will disappear visually.
This is a force along the length of the section to be removed. If you push on both ends, this force is called compression, while it’s called tension if you pull from both ends. There is probably some mechanical force along the benchwork. If you were to simply remove that section, think of what would happen to what was left. If the remaining ends shift inward a bit, the removed section was under compression. I’m guessing there wouldn’t be much of a shift, but you want to either allow it to happen or correct for it before you start laying track.
I would lean toward cutting the roadbed like most have advised. But there is a caveat…This layout won’t be moving around, will it? It’s small enough (in original form) that’s possible, not quite sure how much larger yours is or your plans for it.
If moving is part of the plan in the future, I’d say don’t cut the subroadbed, just build the bridge around it. It’ll be much stronger that way if the benchwork ever does get flexed.
Don’t get me wrong. I love my bridges. In a basement where wall and floor move depending on the water content of the surroundings, they are periodically a source of maintenance woes. If you do cut, be sure to do your reinforcing first to hold everything in place, then cut through and remove the subroadbed.
I did the same as you, but with splined roadbed. I knew ahead of time that I would be cutting out a length and inserting a scratch-built timber trestle.
I formed the terrain under the virtual bridge (it wasn’t installed as of yet), and then cut out the roadbed length where the trestle would sit. I then crafted the trestle and inserted it, being especially careful to ensure the rail bed stringers were meeting the grade at each end. I nipped the bents with track cutters until the entire trestle deck conformed with the grade at each end, and confirmed by temporarily fixing the bridge in place and laying a 39" length of flex track across the bridge with the ends of the track going beyond each end to rails already in place and joining them with metal joiners. I could eyeball the tracks and see where, if any, adjustment needed to be done to ensure the superelevation and grade were constant since it was on a curve there.
Once I was sure I had it all done properly, I fixed the trestle in place with small wooden shims and ground goop at the bottom of the bent frames. I crafted a timber abutment at each end to anchor the ends. Then, I powered the layout and ran a first train across it. Worked like a charm.
Think it through. Write down a list of steps to take to completion. Follow the list by referring to it often as you go. You can even power the rails and run a locomotive across it while it is temporarily anchored if you are careful, or take a long passenger car and run it down the grade from the high end. Watch for hitches, rolls, or porpoising.
I have a question about bridge bases/supports we can see on all pictures.
My plan is to connect two parts of my layout with a module with two bridges (8ft each). I bought a lot of ME bridges but I have a little problem with buying supports which look real.
Are these parts available to buy or they are scratchbuilt? Any tips how to make them ?
The piers and abutments on mine are scratchbuilt from styrene sheet. They’re hollow. I had some prototype photos, from which I guesstimated dimensions to fit the structure I was building, and measured the styrene from there. My trestle piers have a square cap, with four identical trapezoidal sides cemented to it and each other. I filled any gaps with Squadron putty and sanded smooth before painting.
Some of mine are hollow, like Rob’s, while some are .060" sheet styrene, stacked and filed to shape. The ones in the photo which you used as an example are cast in Durabond patching plaster, although Hydrocal would probably work, too.
There’s an illustrated thread here which outlines the procedure:
Rob & Wayne. Thanks a lot for your answers. It was very helpful for me.
I have just one more question.
I guess on these pictures is Atlas Deck Truss Kit. I bought some kits (Item #591) but I don’t have the part which I marked on pictures below. Is this part a separate item to buy ? I didn’t find it in my boxes.
Items are identical on both pictures so I guess it is a product to buy. Unless they are scratchbulit by the same person [:)]
I’m pretty sure that I built those using Evergreen styrene shapes. It’s not anything complicated: heavy vertical supports (H-columns), some lateral bracing (angles or channels), and a base plate to spread the load on the concrete pier. The gusset plates, which make the joints much stronger, are .015" sheet styrene.
In my first photo, that support is floating [:$], although it did re-seat itself every time a train occupied the bridge. [:-^] That picture was taken when the bridge was new, but I’ve since revised the bottom plate of that support so that it actually supports as it should.
Here’s a photo with the bridge removed (that’s it at upper left):
…note the depressions cast into the tops of the piers. There are mating protrusions on the bottom of each support to help keep the bridge in alignment.
