Spanning a room

Discussion in 'FAQs' started by GRAYGHOST, Nov 17, 2004.


    GRAYGHOST New Member

    Spanning a room MAYBE

    I am new to the forum so i dont know if this question has been asked yet.
    Does anybody know the best way to span a 14 foot room without building
    the golden gate bridge? The 14 foot opening is between two rooms and i want the train to run overhead so everybody can see it. I was thinking of a two-level bridge-two rails on top one rail on bottom. One steam engine,one diesel electric and one highspeed bullet. Any suggestions on this thought would be appreciated. Thanks GRAYGHOST :wave:

    An engineering challenge it is.
    and i've always been a rebel without a cause!
    My idea for the span bridge is half-inch copper tubing for the main support.
    And if needed support from the main ceiling. I guess it will look like one of the
    rail bridges crossing the mississippi river. I can solder on support legs off the copper tubing to support the two rail beds on top. and hang the lower rail bed. Not sure exactly what it is gonna look like. The rest of the track is gonna run around the room on a shelf system. I just thought a spanded bridge would look nice going across the room. a more open bridge then covered bridge. I hope this gives better insights on my thought thanks once again GRAYGHOST :thumb:
  2. jetrock

    jetrock Member

    Sounds more like the Bay Bridge to me! The main problem is that if the track runs above people's heads, they'll only be able to see the UNDERSIDE of the tracks and whatever the trains are running on. A bridge can be relatively see-through (although daring is the soul who runs a model train that high off the ground with nothing to keep it from falling ott!) but even then mostly people will see the bridge, not the trains.

    A 14 foot gap will be a real engineering challenge--not sure if anything scale-sized could easily bridge that distance without a couple of supports in the middle to keep it from plummeting from the ground.

    Another consideration is access--how will you re-rail those trains when they inevitably derail?

    And what else will the trains run on? I assume you'll have three reversing loops on either end to allow the trains to go back around on, rather than just scooting back and forth?

    Kind of a unique idea...but definitely one that presents some difficulties.
  3. Matthyro

    Matthyro Will always be re-membered

    Welcome to the Gauge greyghost.
    WOW that is quite a gap. Will you be able to have hangers coming down from the ceiling to support the track? If not, the beam you need to cross 14ft. will have to be strong enough and maybe you will need asteel beam that will not take up as much room as wood.
  4. Ray Marinaccio

    Ray Marinaccio Active Member

    Welcome to the Gauge Grayghost.
    You could build a suspension bridge sort of like the Brooklyn bridge.
    Instead of having the piers go all the way to the floor, have the tops of the piers attached to the ceiling.
    Then attach tinted plexiglass to the bottoms of the piers running the whole length to simulate water under the bridge.
  5. Bikerdad

    Bikerdad Member

    What you don't explain is how high the bridge is from the floor, where you can put your supports, etc, and what scale you're dealing with. Assuming that you need to span the entire room, and you can only put supports at the end, then your best option would be either a bridge suspended from the ceiling, an I-beam, a fairly stout truss, or an arch. Suspended from the ceiling works fine, but it doesn't say "bridge" in any meaningful sense. The I-beam is the easiest, if you can either find a lightweight aluminum beam that works, use a piece of engineered lumber, or if you have the skills, make a beam of either metal or wood. The truss is the one most "railroady", but also will take a fair amount of work. Lastly, the utility of the arch depends a lot on how much arc you can put into it, which depends on how much clearance you need at the buttresses combined with how high you can take the arch. You can start the arch below track level and take it above track level at the apex, if you do a two-beam arch. A single beam arch must, by definition, remain below the track level. Doing an arch means you have to have some means of bending your beams (twin beam arch can be done using 1/2" copper, single beam would best be done with 3/4"). If you do the bridge out of copper, regardless of which bridge, then know that soldering plumbing (essentially what you're doing) involves much higher temperatures than normal MRR soldering. If you already know how, then bob's yer uncle!

    Yes, I think too much about bridges....

    The final option, which takes this to another realm entirely, would be to craft it out of foam and fiberglass. If you know how to make surfboards or modern model airplanes, you're set.

    Regardless of your material, remember the keys to building a good bridge are strength, durability, and light weight. Unfortunately, balancing the three keys is the trick, always complicated by the building site's characteristics.

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