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Swamp bridge anchoring failure

swamp bridge floated downstream

Our swamp bridge floated downstream during the recent flood.

The last time it floated it only went 10 feet and I thought the anchoring job we did after that would have kept it in place.

Maybe there's a better way to anchor it I'm not thinking of?



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The best way to keep a bridge from floating away is to make sure it stays above the high water level. How high that is depends on how long you want to keep your bridge. :-)

But your recent 100-year flood seems like a good base level. Keep the bottom of your bridge six inches above that level and you should be fine for the forseeable future.

Comment by Roland_Smith Sat Mar 14 17:28:54 2015

How did the bridge become unattached to the poles it was anchored to; did the screws rip out of the wood?

I wonder if something like ropes or cables attached to the bridge on one end and to cinderblocks on the other, allowing the bridge to float but not go far, would work? Or maybe attach the cable ends to nearby trees instead; in a 100-year flood the forces might damage the trees a little, but the bridge certainly won't go far even in currents that might drag a cinderblock.

Comment by Rae Sat Mar 14 19:16:01 2015
I would think a substantial cable around the bridge and a nearby tree or a ground anchor would be sufficient. Only try to hold one end of the bridge so debris doesn't break the cable.
Comment by Brian Sat Mar 14 22:49:13 2015

I think you should "design for failure". Tether the bridge deck to a large tree so it doesn't go to far in a flood and reinstall it afterwards.

How many bridges have you made so far??

also thought you should have pursued the Zip Line approach more thoroughly. That wouldn't wash out and would keep your feet dry.

another idea is a raft floated with 4 55 gal. drums. use a permanent line across the creek to pull it. tether so it doesn't wash away in the 100 year flood that comes twice a year

Comment by Tom Sun Mar 15 09:45:47 2015