# Removable bridge?



## wchasr (Jan 2, 2008)

Greetings Brethren & Gentlemen!
As I've completed my first loop of track this summer

















I allowed for expansion and to that end know that I wish to continue the closer switch stright out for close to 20 feet before I make a gentle curve to the left again towards the back yard. I will be planting a row of hedges in front of it as a visual block leaving only the original loop visible from the street. My plan is to put a gate in to traverse from the front yard to the back (for mowing mostly) so the need for a removable bridge wide enough I can pass a riding lawn mower thru has presented itself. I'm thinking either a thru girder deck bridge looking like sections but built as one piece or a larger more decorative truss bridge? I want to build this over the winter but do not have access to a welder nor knowledge of how to weld. I'm limited on funds this year too...been spending too much on trains lately. so purchasing one is out. My focus is mostly modernish trains so a wooden bridge while beautiful is not in the cards for now. Simple and easy is the key for now and upgrade-able later... 

What have other folks done to solve this type of problem? 

Chas


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## Semper Vaporo (Jan 2, 2008)

Nice looking layout.


As for "modern" bridges... even the most modern equipment often is running on ancient track that is suspended on/in old bridges, so a wood bridge is not totally out of place. You can also make it look like an "under girder" bridge and paint it metalic gray or black.


My track was all elevated and I also needed a way to get the lawn-mower from one side to the other. Although I still had a couple of "duck-unders" inside each loopback, I put one removable bridge between my loopbacks. I initially just made one section of the wood elevated structure to be removeable, but then I made a bridge from steel shelf brackets. It is an inverted arch suspension bridge patterned somewhat after some Interstate highway bridges. You can see it in my YouTube video:




Mine is only about 4-ft wide, but I think it could be more like 5 or 6 ft if you can get long enough shelf brackets. Mine was simply limited by the lengths of the shelf wall mounts that I could get at the hardware store. The horizontal members are "C" shaped brackets that would be vertically on a wall and support "arms" to hold shelves. They are about 1/2-inch by 1/2-inch and 4-ft long. The arches are a thinner "C" shape like would go inside a cabinet on the side walls to hold small clips to support the ends of shelves. The bracing between the two lengthwise halves are just short sections of the two materials. All these pieces are just bolted together with short bolts and nuts. I didn't even have to drill very many holes because the pieces have so many holes in them anyway. The arches connect to the base with simple angle brackets. I initially thought the base material would be strong enough to support the train and the arches would be just decorative, but after I built the main part, I put my engine in the middle with the ends supported about 1 inch from the table top and the whole thing sagged terribly... it was up hill either direction to get off the bridge! So the vertical suspension members are important. I used 1/8-inch copper coated welding rod. The copper is too thin to do any good at keeping it from rusting, but looked good for a while! There is "X" bracing between the cross members between the two arches that are just more of the welding rod hooked into the slots and a drop of epoxy to stablize the connections.

If I were to build another one, I think I would use aircraft cable for the suspension cables. I considered bicycle spokes but they are quite expensivve!

To install the suspension, each wire has a hook bent in the top end to catch in one of the slots (for the shelf clips) and a drop of epoxy holds it in place. The other end fits down through one of the slots (for the arm brackets) in the bottom channels and there are enough of the slots in both parts to get the rods nearly vertical without much problem. Once I had all the rods in place (and plenty long to be bent over inside the "C"), I turned the bridge over so the weight of the "bottom" of the bridge would slightly compress the arch. I then just bent each rod over, starting in the middle and working my way to each end alternatively (one on the left of the middle, then one on the right, then back to the left and then the right, etc.) until all the rods on both sides were all bent over and locked in place. Then I put tape over each of the slots to seal them temporarily and poured in epoxy to fill the channel and hold the rods in place. (I removed the tape once the epoxy was set.)

I am not sure of the strength of the unit, but I did pull down on the middle of it when it was in place and it would not deflect with my timid tugging on it. I think if I could get a good grip on it and somehow not on a piece that might bend by itself, it could possibly support my ample weight.

One warning! I built mine for my 1:32 scale models. A friend then came over with some non-1:32 scale equipment and my bridge was not wide enough for some of it, nor were the cross members at the open ends high enough for the stack of his Shay to pass under. When he runs his Accurcraft 3-cylinder Shay, he has to remove the top of the stack (it unscrews) and we sometimes have to reach under the bridge and up to the ties to center the track perfectly so the window awnings on the cab don't catch on the arches.


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