Wooden bridge for 2000# tractor to cross creek

[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.