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  1. #1
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    A different bridge

    A different bridge-img_1066.jpgA different bridge-img_1065.jpg

    Made from a 24" ID pipe with smooth interior. This one, 6', was a test for a 24' version. Pipe was cut in quarters, comp roofing screwed down center, 2x4 for keel lagged in from topside. Splice between sections is held sturdy with large zip ties. It works, cheap, rigid, easy to carry in. This short one would have worked without the 2x4 but long version will need it. I'll have a video of that when we get it in.

  2. #2
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    Interesting concept. Is it rigid? Is there only one stringer underneath the pipe? How are you planning on attaching it to the abutments while making sure it won't roll axially? There is going to be a lot of torque applied to make it roll if someone strays outside of the center line with only one stringer. Any concerns about it holding debris, dirt, and water since it is a cup shape and doesn't appear to be self cleaning like a typical ladder bridge? That plastic (HDPE I presume?) is going to be wicked slippery when wet.

  3. #3
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    This 6' one did not need the 2x4, a test. 8' sections are stiff enough to stand on with minimal deflection, but the wood is needed for long term. Sections are bolted together via the wood. This one is simply dug into the soil, at an angle to drain. Staying in place. Composite roofing for traction works well, and free.
    Long version will have some stays along the run to keep it in column.
    Someone will ride off of it.

  4. #4
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    We use these as full tubes for making speedball, paintball courts. They are very ridged when whole. The added support down the length should be suitable for rigidity reinforcement. It looks as if a 4x4 pressure treated timber was used, this is good!

    Figure out the proper cuts and you could make some interesting floating berms.
    Observe, report.

  5. #5
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    I think i'd rather put the 2x4's on the inside with the roofing on the outside. The roofing might not last as long, but should still work pretty well. It would be almost like a two foot wide log, and it wouldn't roll. No worries about any draining because it would always slopw down from the side.

    If you install it like shown above, make sure you add some drain holes to each ridge. With it angled upward, some rain/leaves will get in the sides and pool in the bottom of each ridge. Without drain holes, this would add weight, and if it freezes, could cause serious structure problems.

  6. #6
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    Can't wait to see the video!

  7. #7
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    I second the drain hole idea for standing water = mosquitos

    Way to be resourceful though, big thumbs up!

  8. #8
    I need skills
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    Any photos of this placed on the trail?

  9. #9
    Zach Attack
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    Skin should be on the bottom where the tension from deflection is. Heavy welded mesh screwed down on top of curve with roofing screws would provide better traction.

    FYI, our goal developing sweet local sustainable trail is to utilize natural local materials as a priority. Plastic and toxic PT lumber is a challenge in our day to avoid but worth it. We picked up a $100 guide for our chainsaw and build beamed bridges utilizing lumber. Even an arched beam out of a bent tree. Sweet stone arched bridges... The stoned bridges are the funnest to build and a 6ft span one only takes a few days with a couple people. More than willing to share the technique!
    You can check out the stone arched stuff at our website...forest trails alliance trail forest city
    z
    Learn to love it[SIZE="4"][/SIZE]
    www.foresttrailsalliance.org

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