Wooden bridge for 2000# tractor to cross creek

[kevininor]

Hello all! I have a property divided in half by a creek. There is currently a 20' bridge in-place with concrete footings at each end with two 6x12 timbers for the span. The timbers are 64 inches apart and the current deck is made from 2x6s. I need to replace the 2x6s as they've had a good life and flex under the weight my my little JD X330. I'm wondering if replacement 2x6 boards will work or if I'll need to upgrade to 4x6s to support the live weight of a compact tractor.

Thanks for any and all input.

 

[Menagerie-Manor]

Where are you in the world, anywhere near sawmills in lumber country. With the lumber prices being what they are for something like that I would probably source full dimension 2" thick or more Spruce planks.

 

[Grumpycat]

If the 2x6's are shot why are the 6x12's still good?

 

[RalphVa]

I researched the building of a new bridge across a little 6-8 ft stream a couple years ago when we were having troubles in the wet 2018 keeping the underflow pipes clear under our present tractor crossing. Other tractor guys in our congregation said they've built bridges using 3 or 4 railroad ties. I figured on getting a boom and quick release thingies to pick them up and to put them across the stream. Weather dried up, and our present underflow crossing is working fine the last 2 years like it did for a number of years before that. Gave up on the idea of relocation.

 

[LouNY]

Many of the smaller wood decked bridges around here used 2x6's on edge for the deck.
These were then oiled and or tar and stoned over the tops.
Another option that I have seen used for bridging are large truck boxes, either dumps for narrower bridges or a pair of flat beds side by side for wider ones.

 

[deezler]

Here's my corona lockdown project from last year. Holding up perfectly so far.

Building my tractor bridge across the creek

Hi all, Thought I would make a dedicated thread for my bridge project just in case anyone wants to follow along or search for it in the future. We bought our 19 acres in 2012, sold off a couple parcels to get down to 10 acres, of which a little over 2 are on the other side of a modest creek...

www.tractorbynet.com

 

[kevininor]

Thanks for the replies. I'm in Eugene, Oregon so definitely in sawmill territory. The 2x6s look very weathered and, in general, the property hasn't been maintained for about 10 years. The current 2x6s are untreated, but flex so I don't think they're completely shot. I get zero movement for the 6x12 timbers so I'm inclined to think they're okay.

 

[dieselscout80]

You could add say 8" to 10" window/door flashing tape that covered the 6" face of the 6"x12" to prevent water from getting in them before replacing the 2"x6".

 

[bcp]

The problem for building a bridge for a 2000 pound tractor is that someday someone will drive an 8000 pound tractor or truck across it.

Maybe get something like this.

1984 Fruehauf 22' Flatbed Pup Trailer

inside frame, 11R22.5 tire. *Farm use only VIN: 1H4P02220EF095901

www.mbauction.com

Bruce

 

[Menagerie-Manor]

Thanks for the replies. I'm in Eugene, Oregon so definitely in sawmill territory. The 2x6s look very weathered and, in general, the property hasn't been maintained for about 10 years. The current 2x6s are untreated, but flex so I don't think they're completely shot. I get zero movement for the 6x12 timbers so I'm inclined to think they're okay.

If you can try and find a sawmill that can cut up some spruce for you, there is a mill in Drain just off the 5 you could try. Spruce is tough stuff and is traditionally used for scaffold planking and really takes a beating.

 

[jmc]

if your decking boards are individually cantilevered outboard of the 6x12s, strapping all the ends of all your decking boards together would distribute your load among several adjacent boards.

 

[Doughknob]

How wide are your wheels, on the 2000lb tractor?

 

[fried1765]

If you can try and find a sawmill that can cut up some spruce for you, there is a mill in Drain just off the 5 you could try. Spruce is tough stuff and is traditionally used for scaffold planking and really takes a beating.

The type of spruce that I am familiar with also rots more rapidly than most other lumber.
Hemlock is a bit more rot resistant if you have any in your area.

The OP does not mention the span of the 6x12's, but dead load weight must be considered.
I would suggest keeping the decking material weight to an absolute minimum.

 

[Williy]

If you can get some oil field pipe and put the wood
over the top or just use all pipe??
In Texas we have cattle guards

willy

 

[Gee Ray]

You need to check the weight you can load onto 20 foot long 6 x 12. I think you would be ok with the JD x330 as it is around 500 pounds but to go any heavier I do not believe the beams are big enough.

 

[fried1765]

You need to check the weight you can load onto 20 foot long 6 x 12. I think you would be ok with the JD x330 as it is around 500 pounds but to go any heavier I do not believe the beams are big enough.

Two problems!
Very long span for 6 x 12, and only two beams!
I would not put more than 500 pounds live weight on that bridge!

 

[oosik]

BCP - that was my exact thought. Build it for your 2000 pound tractor and somebody, like me, tries to cross with my 10,000 pound Kubota. And you can assume that a whole lot of folks have no idea how much their tractor weighs.

What if a friend attempts to drive across with a pickup load of gravel.

 

[bdog]

20’ isn’t very far. Look at some trailers and see how they are constructed. Wood scares me because it rots. I wouldn’t assume the 6x12s are good if the 2x6s are rotten. I would replace the main beams with some I-beam. Steel supplier should have charts for acceptable load on a 20’ span. Might even go with four beams so your decking doesn’t have to be as strong. I have fell through a wooden bridge in a pickup and isn’t fun. I didn’t crash into the creek but two of my tires broke through.

 

[jaxs]

if your decking boards are individually cantilevered outboard of the 6x12s, strapping all the ends of all your decking boards together would distribute your load among several adjacent boards.

I vote for this.

 

[Erik M]

If you have a concrete abutments I would look for some salvaged steel I beams to replace the 6 x 12 and use at least three, and then your problems should be solved. Steel isn’t cheap but you will only fix it once.