The bridge was a little bouncy, but otherwise seemed structurally sound - t hat is, until now. I had hoped that by placing the ends of the tree trunks on gravel and some pressure-treated 4x4s it would last for many years, but the trunks have rotted in the middle and begun to crack, and the bridge is no longer safe.
The reason I cut down a couple of trees in the first place, was that even t hough it apparently exists, it's very hard to get ahold of 20' pressure tre ated lumber. I had thought that a couple of 4"x6"x20' beams might work wel l to support the bridge - though I never did any actual load calculations.
I'm not feeling the love for the work involved of cutting another couple of trees every 5 years, so I'm looking for a better - and hopefully simple so lution. I don't really have the energy or skill for something fancy. If I could get the 4"x6"x20' pressure treated beams (and a friend to help move them), and if they would work in this application, I would do that. But fa iling that - is there another way to solve this problem? (like maybe nailin g together some shorter overlapping 2"x6" boards?).
Trying to keep it as simple as possible. Thanks in advance for any ideas.
Photos of the current bridge here: https://www.flickr.com/gp/7865232@N08/91 04G5