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  1. #1
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    need help designing wood bridge for 25" span

    Hi all: I've looked at blueprints on the IMBA website and USFS for that matter, and everywhere else Google would take me, and don't find anything pre-engineered I can use. I am confident I could design and build a durable bridge myself, but a pre-engineered structure would be a big help with the permitting agencies I'll have to deal with (state parks and potentially a city building dept.) in developing a couple new trails. Any help or direction would be appreciated.

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  3. #3
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    Smile thanks, already found most of these

    What we think will help with the permitting authorities is pre-engineered 2X or 4X bridges we can build ourselves; it's the "official" drawings I need for the reviewing authorities to look at and feel comfortable that we know what we're doing.

  4. #4
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    Did you take a look at the Rainbow Bridge?

    The plans cost $25 and you can buy materials from them or your local lumber yard.

  5. #5
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  6. #6
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    Quote Originally Posted by TFitz
    Hi all: I've looked at blueprints on the IMBA website and USFS for that matter, and everywhere else Google would take me, and don't find anything pre-engineered I can use. I am confident I could design and build a durable bridge myself, but a pre-engineered structure would be a big help with the permitting agencies I'll have to deal with (state parks and potentially a city building dept.) in developing a couple new trails. Any help or direction would be appreciated.
    Seems like a 25" bridge would not need much pre-engineering.
    Live to ride!

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  7. #7
    Big Gulps, Alright!
    Reputation: Berkley's Avatar
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    Give me 30 minutes, a couple of 2x4s, a hammer and nails...

  8. #8
    Builder of Trails
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    Quote Originally Posted by TFitz
    Hi all: I've looked at blueprints on the IMBA website and USFS for that matter, and everywhere else Google would take me, and don't find anything pre-engineered I can use. I am confident I could design and build a durable bridge myself, but a pre-engineered structure would be a big help with the permitting agencies I'll have to deal with (state parks and potentially a city building dept.) in developing a couple new trails. Any help or direction would be appreciated.
    Email me. I have a .pdf document that I think will help you titled "Standard Details of Pre-engineered Bridges for Mountain Bike Trails."

    D

  9. #9
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    Thanks for the responses. I've looked at the IMBA doc, and the trouble is it stops just short of the longer span I need for the two stream crossings required. I looked at the Rainbow website, and we need something a little beefier; both for load and weather durability. I'll look at the USFS drawings shortly. Again, the issue is more credibility with the reviewing agencies than our ability to actually design and build the bridges.

  10. #10
    NOT Team Sanchez
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    shoot dude, this is an easy dilemna, build a big kicker on one side and a landing on the other
    I like bikes.

  11. #11
    beer thief
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    I sent you a PM about this.

  12. #12
    sunnyside up
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    Quote Originally Posted by wasea04
    shoot dude, this is an easy dilemna, build a big kicker on one side and a landing on the other
    Breeedges? We don need no steeekin breeedges!
    "...So forget all your duties, oh yeah! Fat bottomed girls, they'll be riding today..." Freddie Mercury

  13. #13
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    Again, thanks for all the responses, esp. Radair. This will be a trail for both bikers and hikers, so I don't feel comfortable asking people on foot to jump a 20+ foot gap. :-) Also, the land managers want the stream crossings, seasonal tho' they are, protected, so a ford is no go. We still may be a few seasons away from getting the bureaucratic hurdles jumped, but I'll post project pics when we're done.

  14. #14
    NOT Team Sanchez
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    Oh come on the hikers can run and jump it............

    Here's a show off shot of a new gap stepdown (21' tip to tip but we usually end up about 24-25'0I built on a B line of "my trail," 45 stunts and maybe more in a 1 1/2 miles of trail.
    Attached Images Attached Images
    I like bikes.

  15. #15
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    Quote Originally Posted by TFitz
    Hi all: I've looked at blueprints on the IMBA website and USFS for that matter, and everywhere else Google would take me, and don't find anything pre-engineered I can use. I am confident I could design and build a durable bridge myself, but a pre-engineered structure would be a big help with the permitting agencies I'll have to deal with (state parks and potentially a city building dept.) in developing a couple new trails. Any help or direction would be appreciated.
    I don't know what your budget is like, but there are several good manufacturers of pre-engineered bridges that are delivered ready to assemble.

    I have had 7 installed in the past 14 months that range from 20' to 80', and all of them came ready to assemble with small crews, and came with the certified structural engineers drawings and calculations that met all permitting requirements.

    You can order them for various purposes that meet all local codes pertaining to railing systems. The ones I ordered were intentionally over-built to handle anything up to a 5,000 lb maintenance vehicle that could fit within the 60" width....which allows me to get my small excavator, over the bridge.

    The ones I have used in the past have been from Western Wood Structures, and Wheeler Bridges.

    The nice part about bridges like these is that your pretty much can't be questioned or challenged on the bridge, so you have a pretty good legal buffer.

    Hope this helps!

    Photos of a 40' and 60' bridge installed over the past 6 months.
    Attached Images Attached Images
    Last edited by JamR; 01-16-2009 at 03:44 PM. Reason: Photo Additions

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