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View Full Version : How Do I Build A Bridge?


fellsbiker
October 21st, 2003, 11:26 PM
|Warning: This post has nothing to do with the fells!|

I wanna build a bridge. For an ATV. Not a quad abut one of those "off road go karts" Like this
http://www.gokartsupply.com/286pict.htm
So I ride it in there private woods near my grandma's house. And I've gained alot of insight on just what it takes to make a trail. With only one user, even if that user has a 6.5 HP motor, it can be really tough making something that will not fade away to nature. Anyway, I'm to an area that is kind of deep mud, almost a small pond/swamp, but not quite. I only have access to this one corridor so I have to go over it, and I really don't have very much ground clearance on this thing, deep mud is a big no no. So I need to make a bridge. And I figure I've come to the right place, you guy's have built a lot of bridges. My problem is I can't come up with a construction technique that fits the problem. I really have very little money to spend on this thing. One thing I do have is a free unlimited amount of wooden palettes. They should be wide enough for me to drive across. But if I just lay them directly on the mud I think they will get swallowed up by the mud, or at least knocked majorly out of alignment and when i try to drive over i'll just end up knocking them all out of alignment. I can't think of a *cheap* way to make a raised bridge out of these pallets, ones that wont collapse under the force of a 250 LB go kart + 140 LB rider. It doesn't need to be high, not like the new MTB loop bridge at the fells, thats huge, I don't have to worry about water flow underneath or animals crossing. As long as you can drive over it it doesn't need to be nice or neat or pretty. Another problem is I can't tell how long it goes for, so I have no idea how long it needs to be. I was thinking about a way of chopping up a tree trunk into 1.5' sections and using them with the palettes on top, but i don't have a chain-saw, or a tree to kill :-) But I'm afraid if I used anything with a smaller diameter, like a cinderblock with the palettes on it, it would just fall right over. I'm not sure but if anyone has any ideas, let me know.

October 22nd, 2003, 01:01 PM
You have no resources, you don't know how far you have to go, you are alone to do the work, and you don't have a plan.

Sounds to me like it is'nt mountian bikers you need.

It's Moses you need.


:) good luck :)

bill

fellsbiker
October 30th, 2003, 02:41 PM
ha ha, what i need are cinderblocks or milk crates, lots and lots of either, or lots of both. Theres a farm near by and they ahve gigantic stacks of palettes I'm sure if I ask they'll let me have a truck loads. I need the NEMBA to come over to woburn and build me a "bog bridge" :-)

mtbtom
October 30th, 2003, 10:38 PM
how about something like this?

fellsbiker
October 30th, 2003, 10:44 PM
I know I'm using used wooden palettes and the like, but still, I wouldn't want my bridge to be THAT ugly!!!

massmtnbikn
November 5th, 2003, 12:54 PM
If you can live with a little sinking and a little mud, I would think you would want to 'float' the bridge with displacement rather than solid footing to secure it. Assuming the pallets are wider than your rig, you might even be able to tie them together in a chain.

Start after the ground freezes.

johnbryanpeters
November 5th, 2003, 04:03 PM
...Start after the ground freezes.
Sink after the ground thaws... ;D

fellsbiker
November 5th, 2003, 04:12 PM
Yeah I've pretty much decided to just lay the palettes directly on the mud, if I can get enough of them I'll do 3 layers each offset. There is a farm nearby with tons of palettes and I don't think they do anything with them, there are piles of them all over. Now if the slats on the top of the palette are offset at al from the slats on the bottom, then with some 1 1/4" wood screws I could, with a power screw driver, go between the slats and screw each palette to the two beneath it.

massmtnbikn
November 5th, 2003, 04:37 PM
Sink after the ground thaws... ;D


Yes, but that will be after the 30 day money back guarantee :) When I think of deep mud, I think of 6, maybe 12” deep. You don’t think a series of pallets could keep afloat with the limited use and muddy stag conditions he’s talking about?

Fells, I was thinking more of single pallets tied at the ends like a chain to give it flexibility for elevation changes but still stay together. I think you will find your design will break apart in the unsupported areas.

Try a single pallet and see what it takes to sink it.

fellsbiker
November 5th, 2003, 04:45 PM
See my thoughts were just the opposite. For one thing I don't want to use rope because it will dry rot and be put under a lot of pressure, second, I can't know how deep it is, but I think its pretty deep mud, and I think a single layer will put all my weight on one single palette, and I'm sure it will sink right in. If I do the layers, and rigidly screw them together, when I drive across it my weight will be much more spread out, and if one of the palettes is over a particularly soft spot, it will be much less likely to, well, turn into this...
http://www.fellsbiker.com/photos/albums/mtbloop/4.jpg
:-)
Plus there isn't much elevation change, is only going over mud, and I will be building it on site so I won't be attaching palettes together until I have already laid them down where they are going to stay.
I think this plan just might work, if I can get the palettes, and the screws... and if the mud isn't as bad as it looks... Hopefully theres no open water but their might actually be.