Metals406
Granfodder Runningsaw
The stringers for that bridge were 30' long; I think about 6X16. I used three stringers. Width between the rails was 6 feet, to accomodate horses (they don't like being fenced in between the overhead truss pieces).
Built this one on the same trail, same gig with the sawmilled lumber pieces, but it was "only" about a 2.5 mile hike. 32' stringers, 6x16 again.
Edit: the interesting thing about these bridges and doing them that way: when we first went through and built the trail in the spring, we could not run power equipment due to noise restrictions for nesting birds. So when we had to saw through the logs we used crosscut (hand) saws. It's where I learned to file crosscut saws; spend an hour or so pulling a dull crosscut and you'll be motivated to learn to file them.
Upshot of it was, we were working on a fairly steep hillside, so we had to go quite a ways uphill and downhill of the trail to find a place to safely stand to run the hand saws. Consequence of that was, we cut the logs about 30 feet (and one of them 32') long. Pulled them out of the way and built trail.
Come winter, we could run power equipment, and carrying in an Alaskan mill all that way just seemed easier than packing in the lumber.
Who did the structural design for your bridges?