this is crossposted from a thread on tigerdroppings.
Quote:
Bridge span is 30 feet. My grandfather put some steel beams across it in the late 1940s. They're about 12" tall and 8" across (not sure the proper way to describe those dimensions).
There are four total beams. Two pairs about two feet apart. And about 6 feet on centers.
I decked the bridge with full cut 3x10" pine.
Log trucks will be 80,000 pounds. But only half the load will be on the bridge at any one time. I guess the rear axle might carry more weight, so maybe a max of 45-50,000 at a time.
Here are some photos. Thanks for your thoughts and advice.
v 
