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  1. #1
    Trail Tire TV on blogger
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    Build a longer lasting bridge

    this is really only important if using standard dimensional lumber (2x joist style) I have built a good amount of them now this way and can honestly say the "wings" help a good bit making the bridge last longer by preventing roll out but also makes it stiffer and bounce less...

    Do you NEED to do it, .... no Will it help .... YES!

    Trail Tire TV: Bridges with wings...?
    Going to try and bring Trail Tire TV back. go take a look... http://trailtiretv.blogspot.com/

  2. #2
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    Nice. A different (may be more trouble) way to do the same thing is to attach the bridging ("cross braces" in the link) to the joists/stringers with 2X4 cleats, so you're nailing/screwing through the strong part of the wood and avoiding the end grain issue. "Wings", if longer, also make a good base for bracing a railing if one is required. Another detail that will help the bridge's longevity, treated lumber or not, is to roll out a strip of building paper on top of the stringers before attaching the treads.

  3. #3
    Delirious Tuck
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    T - Nice work man. I'm going to forward the link to a local LM, I can either go big with rock or boardwalk/bridge it. Rock will take way too many man hours while boardwalk we can offsite the work, hike in, and assemble.

    Any idea what decking and stringer combo for horses? Assuming for bikes and foot traffic you're doing either 2 or 3 stringers with 30'' decking?

  4. #4
    Trail Tire TV on blogger
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    Quote Originally Posted by TFitz View Post
    Nice. A different (may be more trouble) way to do the same thing is to attach the bridging ("cross braces" in the link) to the joists/stringers with 2X4 cleats, so you're nailing/screwing through the strong part of the wood and avoiding the end grain issue. "Wings", if longer, also make a good base for bracing a railing if one is required. Another detail that will help the bridge's longevity, treated lumber or not, is to roll out a strip of building paper on top of the stringers before attaching the treads.
    ya, I tried that, but honesty, when you get that many screws in such a small piece of wood, it just splits out and you end up worse off..




    Quote Originally Posted by thefriar View Post
    T - Nice work man. I'm going to forward the link to a local LM, I can either go big with rock or boardwalk/bridge it. Rock will take way too many man hours while boardwalk we can offsite the work, hike in, and assemble.

    Any idea what decking and stringer combo for horses? Assuming for bikes and foot traffic you're doing either 2 or 3 stringers with 30'' decking?
    horse is a WHOLE diff ball game... needs to be min 4 ft wide... If for horse I usually find a local saw mill and have them cut me oak or something with 3 or 4 4x10 or 4x12 depending on how long and then just deck it rough oak/what ever local saw mill 2x6 or something. ends up stronger and a good bit cheaper... but it'll be a bear to get out there... you can use regular 2x material.. but nail 2 together and use 3 "pair joists" (6 2x's total) still do the wings too,.. just make them bigger!

    definitely pre cut and fit then wheel barrel it.. or drive, or ATV what ever the parts.. lots easer as the only tools ya need are screw driver (impacts are WAY better if ya got one as they don't strip the screws out) you may need to notch something to fit over a rock or some such but a stupid trail saw can do that usually


    as to width I used to do 24-30", but, I've been pushing it out wider as we get a LOT of older hikers and the thinner bridges are harder for them to hobble across... this last ones are 2 joist, 30" wide frame (27" center brace, plus 1 1/2 joist on either side) with 6" over hang on both sides, and the wings push out another 12-16 inches total.. so the main deck ends up around 42" and the wings are around mid 50's. but using 2x12 for joists instead of 2x8 and 2x10.. makes the bridge super stiff with the wings..
    Going to try and bring Trail Tire TV back. go take a look... http://trailtiretv.blogspot.com/

  5. #5
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    In my experience, the first thing to deteriorate with this style of bridge is usually the decking material. I would have concerns about relying on the decking material as a structural element especially if it is of the thinner variety (less than 1.75").

    My preferred method would be adding cross bracing between the joists attached with galvanized joist hangers and nails. Using a joist with a shorter vertical profile will also help reduce the rolling failure mode but is a less efficient use of material. A solid joist foundation also helps greatly to counteract this type of failure.

    We have used concrete wall cap stones as footing pads under the joists on some of our larger bridges (one a 22' span). The larger footprint prevents the bridge from settling as much in softer soils (which can cause the joists to rotate) and adds longevity by slowing deterioration from direct ground contact.

  6. #6
    Trail Tire TV on blogger
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    Quote Originally Posted by aero901 View Post
    In my experience, the first thing to deteriorate with this style of bridge is usually the decking material. I would have concerns about relying on the decking material as a structural element especially if it is of the thinner variety (less than 1.75").
    if the deck boards are failing.. the bridge is unsafe and needs to be repaired/replaced anyway.... ? Decks on houses are built with the same materials using actually thinner boards and most last 20+ years if built correctly.



    Quote Originally Posted by aero901 View Post
    My preferred method would be adding cross bracing between the joists attached with galvanized joist hangers and nails. Using a joist with a shorter vertical profile will also help reduce the rolling failure mode but is a less efficient use of material. A solid joist foundation also helps greatly to counteract this type of failure.
    joist hangers are great, but around here if there is a flood it needs to be wash out and be break down-able so we can haul it out if damaged beyond just re-setting Hangers make it near impossible to take apart. Yes they want it to wash away in a serious flood as it actually does less damage to the surroundings if it washes away (or so they say.. I'm not 100% convinced but it's their property soooo)



    Quote Originally Posted by aero901 View Post
    We have used concrete wall cap stones as footing pads under the joists on some of our larger bridges (one a 22' span). The larger footprint prevents the bridge from settling as much in softer soils (which can cause the joists to rotate) and adds longevity by slowing deterioration from direct ground contact.
    ya... we just use a few of the one million rocks ... not much "soil" in this area But ya.. something solid (rocks, concrete, what ever) keeping the support-contact points out of soil will extent the life of a bridge a good bit.
    Going to try and bring Trail Tire TV back. go take a look... http://trailtiretv.blogspot.com/

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