Here's a link to an article I found awhile back. Might be a good starting place.
http://www.redwoodbridges.com/build_footbridge.html

 

I built a bridge over the creek in the far back of my yard and it was fairly easy except for the three inches of rain we received in one day this past spring. Originally I built it using timbers cut from the yard with 2×6 treated boards crossing it. That turned out to be super strong, but it was far too low and when we got the rains I basically built up the embankments on either side and fortified them more and started fresh with a new bridge. On the second bridge I used 2×10's screwed together on either side and the 2×10's at 12" on center for the center joists, then came back with the 2×6's for planking. It is 54 inches wide and the span is 6 feet, so it overhangs the embankments on either side about a foot. I then filled the voids in the overhang with concrete and made the ramps on either side with dirt. I drive my 900 lb John Deere with me (200 lb) over it and it doesn't budge. I think what I learned on the first one was the sides on either side must be built so they absolutely won't wash away. One side on my original one did and it destroyed the whole bridge. When I re-did it, both sides are now solely built with rock stacked and they have seemed to hold up immensely.

 

Doesn't have to be super decorative but I want it to look strong and well made. No Handrails. The tractor only weights about 500lbs so shouldn't be that tough. If anyone has any pictures of theirs that would be great. Thanks for all the replies.

Eric

 

I found a Great site , I even used there help and built a foot bridge for my John deer (;-)
I call the builder and her took the time to help me Great guy here is the site,.

http://www.redwoodgardenbridges.com

http://www.redwoodgardenbridges.com/Garden-bridge-plans-c-75.html

 

That my friend is exactly what I am looking for, thank you ever so much

 

Even has the same tractor….

 

I built a similar bridge for the same purpose a few years ago. Worked great until my wife fell (walking across) and broke her wrist when the bridge got slippery with wet leaves. I replaced the curved version with a flat bridge.

 

I know this thread is old, but here is how I did mine if anyone is still looking.

 

Concrete support post like what they build for conex container homes when they need to level and raise them off the ground. Very strong concrete supports with rebar. There are DIY videos you tube how to build them. Supports ...then a steel beam or railroad trusses and then jist plank them and whatnot

 

Welcome to the forum, Laramie - we're glad to have you here.
When you get time, drop into the New Member Intro section and tell us a little about yourself, hobbies, shop, etc.
Have you ever built a bridge like that ?

 

I think one of the easiest ways to do this is to get a piece of metal, concrete, or plastic pipe, maybe 12" in diameter, drop it into the creek, and dump some soil around it until you have filled it level. plant some grass and your done. If you contact some local building contractors, you might be able to locate a used one for cheep. Add some headwalls if you think you might have problems keeping the soil in place.

 

I built a big 8' long ramp out of screwed together 2x6s. I broke it in half unloading a 2000lb Tannewitz table saw, but it held way more than 500 lb before that.

Just as an illustration of the strength of 2x stuff. You can get the US Forestry Service Wood Handbook for free from their website, it has lots of great information about what wood can do and how strong it can be in different applications.

 

Look up "Grandpa Mu builds a bridge..."