Need to build a bridge

I need help in the design of a 20 to 25 foot bridge to cross a small stream. There is a culvert there now but the pipe is too small and the road way washes out in heavy rain run off.

The search for a plan for a truss bridge made from possibly white oak has not yielded a plan. The general design can be a king truss, warren truss or other but what I need is the specs of the beam sizes if I use the oak or pressure treated pine to build up beams. Steel is always a fall back but my son and I would like to build it out of wood.

A three ton capacity would do the trick for tractor and attachments. Does anyone have sources for a plan or any suggestions that might help?

Thanks,

Tim

Look at http://www.buildeazy.com/plan_links_bridges.html

Thank you,

Found these too, but need one that is more than a footbridge and flat.

Do a search on "timber bridge". There are a number of resources.
One is
http://www.tfhrc.gov/structur/struc98/ch4set.htm

There has been a large timber bridge program ongoing for the last several years in the Forest Service and other private agencies.

The University of Minnesota Extension has a decent artilce on how to construct a Log Stringer Bridge.

http://www.extension.umn.edu/distrib...es/DD7005.html

Sorry that I am so late responding to your post. The bridge site was a big help planning our bridge. Our problem now is all the rain this summer has held up construction.

Thank you,

Tim