Layout Room EntranceWay Bridges


Challenge & Imagining/Visualizing Finished Product

Its going to be a challenge, but that will make it all worthwhile to make it work.

What I'm having a problem with right now is imagining how to fit the bridges, that are shorter than my 36" wide opening, and their approaching tracks/piers/grounds onto the lifting portion. Its just something about 'visualization'.

I think I need some images/photos to give me some help with ideas. So if anyone has some please post them.
 
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New Idea

After looking at that Jacksonville double track bridge I had a new idea. Instead of utilizing the Walther's bascule kits. Perhaps I could make my arrangement out of 3 regular double track truss bridge kits from Walthers, etc

I would use 2 of those kits end-to-end to provide a nice wide river crossing to my entranceway,...and they would already be a relatively narrow double track arrangement. I could go ahead and use this idea in my planning and building of my RR without waiting to modify the bascule bridges.


Then at some later date I could add the superstructure and counterweight of bascule configuration to one of those regular dbl-track bridges. I would use some of the beam arrangements from that 3rd kit I purchased. And I would have to find an appropriated machinery shed to place in the overhead. Counterweight,..no problem, my bascule bridges are NOT going to be operational,..just for show.



I like this idea,...full width river for the shed's entrance, dbl-track spacing in line with what I have already drawn, and no waiting to resolve details/problems with modifying bascule bridge kits.
 
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'Parallellogramming',...squareness

I've returned to working on my entrance-way bridging project. I figured since I had my 3 layers of plywood deck temporarily in place, now was the time to try and finalize this design.

I was pleasantly surprised at how 'square' all of my original metal framework was ! I did end up have to lower one side by 1/32" to get the staging deck crossing to line up.

Then I decided to address the parallel rigidity. I had been thinking about this addition of a 'rectangular plywood plate' at the upper regions as posted in this photo and the following 2 submissions,....



The swinging bridge is a very good idea, I never thought of it.
That aluminum is about 1" wide, and naturally I would thing of T-hinges, just like you did. Then I thought, full size door hinges would be more reliable. But how to attach them? OK, without starting over, I would apply 3/4" ply or 1" lumber to both the swinging frame and the shed.​
DougL​
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As well as beefed-up hinges, maybe you'd need to add some diagonal bracing to the frame to stop it from "parallellogramming" on the way down and letting the bridge tracks bump into the fixed tracks?
Pete M​




Being a structural engineer, I can tell you that the corner braces you're using will most likely allow the swing gate to rack much too far left and right. In short, they probably don't make the structure stiff enough in the lateral direction.
You can easily improve the lateral stiffness by at least an order of magnitude by simply adding small triangular (say three inches or a bit more on the sides bordering the 90 degree angle) gussets at each corner of the frame. Welding them in place would be best, but self-tapping screws would probably work well enough. I would avoid bolts for that, since the clearance holes would still allow some lateral movement.​
Mark P.





So I added my plywood plate
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And I added a piano hinge to the affair.... to be continued
 
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Piano Hinge?
I have, and still am, debating with myself on the use of that piano hinge on the upper beam. I have no doubts that it is a more 'exact' hinge than many others, and for that reason is the one to be considered in most cases.

But here is my delimma. Should I be depending on that rotation/attachment point way up there to correctly align my crossing tracks down below. Or should I be building the rectangular frame structure as an entity unto itself to align those 3 crossing tracks/bridges, then simply hinge it at the top to move it out of the way, but without be concerns about the hinging point bringing everything else into alignment??

I went ahead and included the piano hinge just in case this was the route I choose in the final decision. It seems as though I am thinking about alternative ideas to accomplished my goals as I go along with the construction of this fixture.
 
As I posted previously I was pleasantly surprised with the 'dimensional fit' of my original mock-up fixture.
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BUT, when I went to add the 8” wide plywood deck to the lower staging level crossing, it did not extend out level across the 3 wide tracks,...rather it drooped at the outer edge away from the frame.
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At first I was not understanding why, as all my metal framing were exactly square, and the brackets I had used were all double checked for squareness. Turns out it had to do with drilling those holes to mount those 90 degree brackets at the bottom of my swinging fixture.

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I decided I was going to have to redrill those holes in replaced alum frames using a drill press to get really accurate placement,...and substitute 90 degree 'corner brackets'

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I got two of those corner brackets out that I had previously purchased for another project. When I got to inspecting them more closely, and with a metal square tool, I found they were NOT exactly square either,...in several directions !!

I was just about to walk out the door yesterday morning to go visit a few stores and see what sort of corner brackets they had. My contractor friend happen to stop by and made the suggestion that I simply use a rectangular piece of my ¾ plywood to assure exact squareness of the bottom portion of the swing up fixture. Why didn't I think of that? I had done that exact thing up top?

No need to go searching for premium brackets, and exact drilling of mounting holes. Here it is pictured in its glued up stage. I'll get better/more-understandable photos tomorrow after the glue sets up.

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Meantime I went about experimenting with cutting some of my proposed 'angled wood blocks' that would be utilized to 'locate' the swing structure when lowered into place. I cut these on a 10 degree angle,...then went ahead and glued those bottom ones into place.
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Ready for fitting the bottom deck tomorrow.
 
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2 steps forward, 1 step back

There are times when my progress appears to follow this pace. Case in point, a few days ago I glued up my new plywood reinforcing panels into my metal frame, and left them sit overnight for the bond to fully develop.
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Turns out I used the wrong glue. I used my trusty old TiteBond ll. It may be great on wood, but not on smooth alum metal. It cracked right off. I had to clean all those pieces up, and resort to polyurethane glue. I also decided to speed things up by adding mechanical fastenings concurrently. So I had to do a whole detail measuring project AGAIN.

Here is that frame structure with the lower 'squareness plate' glued and screwed in place. I also purchased a couple of 4” brackets that will support the lower staging deck 'bridge'.
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Then here is the staging deck placed onto those brackets
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Notice my particular good close fit with the angled butt blocks. The tracks shown in those last photos are just representative as to approx location of the 3 staging crossing tracks. In reality I will eventually lay flex track across that deck and joints, and use a razor saw to cut the angles in place.
Here is that swing-up structure raised up to the ceiling
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...and that structure partially the way up,...clearing the tip of the peninsula....
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You might have noticed those two 'blobs' on the wall that the frame structure is bolted to …
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Turns out I had to some extra sanding of the masonite seams/tape in those 2 areas to get a really flush surface for the structure to sit against while remaining in a straight down/vertical attitude.

Its my intention to utilize 2 sliding rod hasp like this one to 'lock' the lower deck in place. I intend to mount those on the underside of that deck piece at either side. And I am thinking I want to mount them at an angle as I have laid them out there.
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I have found that MANY of these type sliding hasp are NOT built to very close tolerances, so I have gone looking for better ones, and/or a way to modify this large one to fit my desires.
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Next 2 Upper Levels

Once I get this bottom deck very exactly in place, and continuously repeatable, I will begin to work on the two levels above it. I have some curtain rod brackets that appear to be just what I need here.
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They will be screwed to the alum uprights. As you might see they have slots for those screws. That will allow for them to be adjusted up-down as needed for any small dimensional changes of the frame structure itself.
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As I have hinted at previously each side of these decks will be 'individuals',...that is the decks will not be continuous across the span, but rather blank at their centers. The bridge structures themselves will span this center span.....just like real bridges.












There are two reasons for this choice:
1) having the individual ends independent allows for more 'adjustments' in case of misalignments in the future.
2) more realistic appearance.
 
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My intention was to utilize 2 sliding rod hasp like this one to 'lock' the lower deck in place. I intend to mount those on the underside of that deck piece at either side. And I am thinking I want to mount them at an angle as I have laid them out here,...​
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I have found that MANY of these type sliding hasp are NOT built to very close tolerances, so I have gone looking for better ones, and/or a way to modify this large one to fit my desires.​
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I've decided NOT to utilize those sliding bolt hasp. Number 1, they just have too much 'slop' in their fit.


And number 2, why do I need them? I was clamping some pieces of wood just below my wedge shapes in order to hold the whole structure up in place while I rebolted it to the wall. My thought was why do I need those hasp? The bottom deck fit so nice and fine, and with just enough resistance to hold itself in place. So I just screwed two bottom pieces onto my wedge shapes and left it like that. If I ever find a need for more hasp, etc, I can add them later

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Track Gaps

I'm taking a closer look at exactly what I might do for the most immediate gaps in the tracks. I've seen several new products introduced and I know at least one of those would not be applicable as they would not work with my 'sliding connection'.

A couple of days ago I considered placing 'rerailers' on either side of the track gaps.

This morning I thought how about placing the rerailer across the gap, then cut it in such a manner as to provide a stable gap??
 
Laying First Track on Entranceway Bridge

I've been working my way around the lower main level and staging track levels of my around-the-walls layout. I finally reached the entranceway swing-down bridge structure. I figured it best to go forward with laying the staging level tracks across it before I placed the big steel mill section back in there.

As I mentioned before I decided to use rerailer tracks at each of 'couplings' of those staging tracks that were going to bridge across the entrance,....there are 3 of those staging tracks that will go all way around the room.

I decided I did NOT want to glue these tracks and the rerailers down to the plywood,...but rather would screw and tack nail them into place so minor adjustments could be made in the future.
So here is the bridge structure swung down getting those 3 staging tracks ready,..
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......screws are employed at either end of the rerailers.
.....tack nails are employed at the ends closest to cut joint...
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(at first I tried these brass tack nails, but they turned out to be too soft to fully drive into the good plywood, so these others were used)
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I put a metal straight edge across the tracks as a guide when making the razor saw cut.
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and hear is the bridge partially lifted after the cuts to the tracks.
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Have to finish up the connecting tracks today. So far it looks pretty promising.
 
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some comments on another forum...

I always thought a rerailer used across a gap the way you have is a waste. Surely a rerailer is supposed to rerail a car that has derailed crossing the gap, correct? But the rerailer does its job with the slopes and angles at it's ends. sorry, Brian, but I think you've misunderstood how they function, and therefore misapplied them.

After catching shirt sleeves on the exposed rails when my drop down was in the down position and ripping them out of alignment or worse i rebuilt the interface several times to mitigate this problem. Atlas rerailers were the final and best solution. I don't care about the rerailing function but those things are so handy when laid across a gap and cut with a jeweler's saw. Clean solid interface with the rail ends protected from snags.


Gentlemen you have brought this to my attention and I believe I need to do some re-considerations before I continue on with my crossings at the next 2 levels up. I like not having snags, but I also like the idea of the rerailer.


I believe I will leave this staging track level as it is for now, but I did some measurements to determine if I could modify it in the future without encountering significant problems. At the moment I am thinking of mounting two rerailers head-to-head on each track as it crosses the joint between main deck plywood and bridge deck. Now the question is where exactly the join line would be? Lets see if I can get an image up and suggest where it might be??


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This is how I thought I might make my diagonal cut across one end of one rerailer to match up with a second one,.....either at the end of the tracks, or at the end of the plastic stock. I believe I would prefer the end of the plastic stock to try and avoid snags by exposed tracks?


The diagonal cut is an effort to avoid any snags of the tracks with each other as the tracks are moved 'across' one another in their rotation back and upward.
 
Head-to-Head Rerailers

This is what I am talking about when I say mounting 2 rerailer sections over the gap for each track,..
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This configuration would provide re-railing capabilities for trains traveling in either direction,...and for wayward trains approaching the bridge area, I am thinking of having the bridges themselves acting as real bridges do,...actually bridging the 'tall,/cavernous' entrance-way with no 'safety net' under them,...so I had better not have any derails on those bridge tracks !!
 
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I've also noticed a little extra friction in my wood block wedges with the change in temp/humidity of our summer weather vs winter weather. Not enough to affect a design change, just a little extra push to get things lined up at the controlling staging level.

As a result I have changed over to stiff alum plates for my upper two levels,...a bit less friction than the wooden plates.

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And BTW, I have rounded off those sharp corners after these pictures were taken.
 
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Safety/Guard Rails on Bridge Tracks

I was looking at my track inventory to determine exactly what I had for safety rail track. I had 3 long sections of a commercial produced code100 track. That will just barely cover my 3 tracks that cross my entrance way bridges. I need some more.

I had a number of plain bare rail pieces that I contemplated adding onto std flex track. But as I began experimenting with this idea I was having trouble getting a decent close spacing between the two rails. I tried several different brands of track, and carving off a portion of the tie plates to get a closer spacing. But so far less than encouraging results.

My Shinohara bridge track,..
So here is piece of that 'bridge track' I had collected up. It labeled Shinohara


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The sections are about 3 feet long, and it appears the inner and outer rail sizes are the same.


Here is a comparison, the Shinohara track on the bottom and a normal Atlas CODE100 flex track on the top. But there are two different safety/guard rails laid in there. The top rail is another piece of Code100, the bottom one is Code83
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You can see that the molded rail keepers on the stock track keeps the guard rails away from the main rail by a greater distance than with the 'commercial built' Shinohara track. But this apparently is not a problem when I look around at all the prototype installation that vary widely?


Tracks from the end view,...
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I did a very brief little experiment with those bridge track rails butted up against conventional flex track, and found as you said DAVE no rerailing capabilities at all. However I did find that the joint could tolerate a little misalignment without derailing some hand pushed trucks,...actually a bit more than I suspected.

So I have decided to hook things up like this to start out with. I will leave the safety rail track in its longest form all the way to the gap/slot. There it will mate up with a rerailer like this,...

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If for some reason I have problems with this arrangement I can shorten the bridge/safety track, then insert a portion of rerailer in that space.


But I think this will work, ....and I can minutely adjust alignments by ever so slightly swinging the rerailer piece just a bit.


The upper bridge rail would look something like this (with the rail cut properly of course).
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My bridge(s) project is coming together. I've worked out the end fittings joining the decks to the bridges. I'm working on the track and rerailers situation at the ends of both upper levels. i'll have some more photos and a TEST run by next week.


Meantime I am pretty satisfied that I will be able to run trains across the shed's entrance-way with the door open or shut. And I will be able to lift all 3 bridges up and out of the way with one single motion.


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PS: Haven't put the sides, etc on the swing bridge yet as I was working on how and what track to lay on it. BTW that swing bridge is NOT going to be operable,...too many track joints/gaps would be involved.
 
Stiffness of that Swing Bridge

I was a little surprised at some lack of stiffness in the base of that swing bridge, particularly considering the numerous interlocking structure beams there. You can see a little of that dip with this photo. Because of that I backed up my concrete pier supports at either end with a piece of plywood that would allow for another support beam to be attached under the whole bridge across that opening. (that beam would actually pass under that center support structure unlike what it appears in that photo)

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But of course like the real prototype bridges, when I added on the upper structure beams to the model bridge everything leveled out and became much stiffer,....may not need that sub-support piece.


Sub-Support Beam
Just to clarify here are a few pics of a white sub-support beam that I considered installing if I needed additional stiffness. I now don't think I will need it, but it could be done with little additional effort in the future.


getting it ready to push up under..
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FINALLY, running trains across my lower level swing bridge bridge. I've been looking forward to this for a long time.


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FEELS GOOD !


Now I have to get the rest of that lower
 
Entranceway Bridges looking into layout room

Had a little birthday party for my 91 year old neighbor yesterday. (he is the one that grew up next to a major RR crossing that entered London during WWll bombing).

Left the bridge structure in the down configuration so several neighbors could inspect what they might find looking at my layout from outside the shed.
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with upper bridge location
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How about attaching them to the door to the shed and using it to swing them out of the way. I would also add additional hinges to the door to carry the extra weight. The ends of the bridges and corresponding benchwork and track would need to be cut on an angle on the opening side of the door for clearance .
 



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